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<strong>Fuel</strong> <strong>Cell</strong><strong>Projects</strong> <strong>for</strong> <strong>the</strong><strong>Evil</strong> <strong>Genius</strong>
<strong>Evil</strong> <strong>Genius</strong> SeriesBionics <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>: 25 Build-it-Yourself<strong>Projects</strong>Electronic Circuits <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>: 57 Lessonswith <strong>Projects</strong>Electronic Gadgets <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>:28 Build-it-Yourself <strong>Projects</strong>Electronic Games <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>Electronic Sensors <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>:54 Electrifying <strong>Projects</strong>50 Awesome Auto <strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>50 Model Rocket <strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>51 High-Tech Practical Jokes <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong><strong>Fuel</strong> <strong>Cell</strong> <strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>Mechatronics <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>:25 Build-it-Yourself <strong>Projects</strong>MORE Electronic Gadgets <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>:40 NEW Build-it-Yourself <strong>Projects</strong>101 Spy Gadgets <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>101 Outer Space <strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>123 PIC ® Microcontroller Experiments <strong>for</strong> <strong>the</strong> <strong>Evil</strong><strong>Genius</strong>123 Robotics Experiments <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>PC Mods <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>: 25 Custom Builds toTurbocharge Your ComputerProgramming Video Games <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>Solar Energy <strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>22 Radio and Receiver <strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>25 Home Automation <strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>
<strong>Fuel</strong> <strong>Cell</strong><strong>Projects</strong> <strong>for</strong> <strong>the</strong><strong>Evil</strong> <strong>Genius</strong>Gavin D. J. HarperNew York Chicago San Francisco Lisbon London MadridMexico City Milan New Delhi San Juan SeoulSingapore Sydney Toronto
Copyright © 2008 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in <strong>the</strong> United States of America. Except as permitted under<strong>the</strong> United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any <strong>for</strong>m or by any means, or stored in adatabase or retrieval system, without <strong>the</strong> prior written permission of <strong>the</strong> publisher.0-07-159576-7The material in this eBook also appears in <strong>the</strong> print version of this title: 0-07-149659-9.All trademarks are trademarks of <strong>the</strong>ir respective owners. Ra<strong>the</strong>r than put a trademark symbol after every occurrence of a trademarked name, we usenames in an editorial fashion only, and to <strong>the</strong> benefit of <strong>the</strong> trademark owner, with no intention of infringement of <strong>the</strong> trademark. Where suchdesignations appear in this book, <strong>the</strong>y have been printed with initial caps.McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or <strong>for</strong> use in corporate training programs.For more in<strong>for</strong>mation, please contact George Hoare, Special Sales, at george_hoare@mcgraw-hill.com or (212) 904-4069.TERMS OF USEThis is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGraw-Hill”) and its licensors reserve all rights in and to <strong>the</strong> work. Use of thiswork is subject to <strong>the</strong>se terms. Except as permitted under <strong>the</strong> Copyright Act of 1976 and <strong>the</strong> right to store and retrieve one copy of <strong>the</strong> work, you maynot decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish orsublicense <strong>the</strong> work or any part of it without McGraw-Hill’s prior consent. You may use <strong>the</strong> work <strong>for</strong> your own noncommercial and personal use; anyo<strong>the</strong>r use of <strong>the</strong> work is strictly prohibited. Your right to use <strong>the</strong> work may be terminated if you fail to comply with <strong>the</strong>se terms.THE WORK IS PROVIDED “AS IS.” McGRAW-HILL AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS TO THEACCURACY, ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED FROM USING THE WORK, INCLUDING ANYINFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE, AND EXPRESSLY DISCLAIM ANYWARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY ORFITNESS FOR A PARTICULAR PURPOSE. McGraw-Hill and its licensors do not warrant or guarantee that <strong>the</strong> functions contained in <strong>the</strong> work willmeet your requirements or that its operation will be uninterrupted or error free. Nei<strong>the</strong>r McGraw-Hill nor its licensors shall be liable to you or anyoneelse <strong>for</strong> any inaccuracy, error or omission, regardless of cause, in <strong>the</strong> work or <strong>for</strong> any damages resulting <strong>the</strong>refrom. McGraw-Hill has noresponsibility <strong>for</strong> <strong>the</strong> content of any in<strong>for</strong>mation accessed through <strong>the</strong> work. Under no circumstances shall McGraw-Hill and/or its licensors be liable<strong>for</strong> any indirect, incidental, special, punitive, consequential or similar damages that result from <strong>the</strong> use of or inability to use <strong>the</strong> work, even if any of<strong>the</strong>m has been advised of <strong>the</strong> possibility of such damages. This limitation of liability shall apply to any claim or cause whatsoever whe<strong>the</strong>r such claimor cause arises in contract, tort or o<strong>the</strong>rwise.DOI: 10.1036/0071496599
About <strong>the</strong> AuthorGavin D.J. Harper is <strong>the</strong>author of 50 Awesome Auto<strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong><strong>Genius</strong>, Build Your OwnCar PC, 50 Model Rocket<strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong><strong>Genius</strong>, and Solar Energy<strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>(all from McGraw-Hill),and has had work mentioned in <strong>the</strong> journalScience.Gavin holds a Diploma in Design & Innovationand a Bachelor of Science (Honours) Degree inTechnology from <strong>the</strong> Open University, UK.He went on to study toward a Master ofScience in Architecture with AdvancedEnvironmental & Energy Studies with <strong>the</strong>University of East London at <strong>the</strong> Centre <strong>for</strong>Alternative Technology. He also holds <strong>the</strong>Diploma of Vilnius University, Lithuania. He hasundertaken fur<strong>the</strong>r study with <strong>the</strong> Open Universityand with Loughborough University’s Centre <strong>for</strong>Renewable Energy Systems Technology. He iscurrently reading <strong>for</strong> his Ph.D. into <strong>the</strong> impacts ofalternative vehicles and fuels at CardiffUniversity, Wales.vCopyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
For more in<strong>for</strong>mation about this title, click hereContentsForewordAcknowledgments1 History of Hydrogen and <strong>Fuel</strong> <strong>Cell</strong>s 12 The Hydrogen Economy 93 Producing Hydrogen 23Project 1: Testing <strong>for</strong> Hydrogen 24Project 2: Testing <strong>for</strong> Oxygen 26Project 3: Investigating Acid–MetalReactions 27Project 4: Investigating <strong>the</strong> Activity ofMetals When ProducingHydrogen 29Project 5: Investigating WaterElectrolysis 31Project 6: Making <strong>Fuel</strong> from Waterwith a Hoffman Apparatus 334 Hydrogen Storage 37Project 7: Using Hydrogen StorageTanks with Desktop<strong>Fuel</strong> <strong>Cell</strong>s 37Project 8: Boyle’s Law andCompressedHydrogen Storage 38Project 9: Exploring Charles’ Law 39Project 10: Making Your Own “CarbonNanotube” 40Project 11: Generating HydrogenUsing <strong>the</strong> H-Gen 46Project 12: Changing <strong>the</strong> H-Gen Rateof Reaction 475 Platinum <strong>Fuel</strong> <strong>Cell</strong>s 51Project 13: Build Your OwnPlatinum <strong>Fuel</strong> <strong>Cell</strong> 51ixx6 Alkaline <strong>Fuel</strong> <strong>Cell</strong>s 57Project 14: Making Electricitywith Alkaline <strong>Fuel</strong> <strong>Cell</strong>s 59Project 15: Plotting <strong>the</strong> IVCharacteristicsof an AFC 63Project 16: Plotting <strong>the</strong> PowerCurve of an AFC 66Project 17: Comparing <strong>the</strong>Per<strong>for</strong>mance of DifferentAlkaline Electrolytes 67Project 18: Comparing <strong>the</strong>Per<strong>for</strong>mance of Different“Hydrogen Carriers” 68Project 19: Investigating HowTemperature Affects Alkaline<strong>Fuel</strong> <strong>Cell</strong> Per<strong>for</strong>mance 68Project 20: Investigating AFCPoisoning 70Project 21: Investigating <strong>the</strong>AFC’s Need <strong>for</strong> Oxygen 71Project 22: Investigating DifferentGases at <strong>the</strong> Anode 71Project 23: Investigating <strong>the</strong> Rate ofReaction (OxygenConsumption) of an AFC 727 PEM <strong>Fuel</strong> <strong>Cell</strong>s 77Project 24: Disassembling a<strong>Fuel</strong> <strong>Cell</strong> 84Project 25: Changing MEA PlatinumLoading 88Project 26: Experimenting withOxygen and Air 89Project 27: Building Your OwnMini <strong>Fuel</strong> <strong>Cell</strong> 90vii
8 Direct Methanol <strong>Fuel</strong> <strong>Cell</strong>s 95Project 28: Getting to Grips with <strong>the</strong>Methanol <strong>Fuel</strong> <strong>Cell</strong> 98Project 29: Decommissioning andRecommissioning aMethanol <strong>Fuel</strong> <strong>Cell</strong> 99Project 30: Building a Band-Aid ®<strong>Fuel</strong> <strong>Cell</strong> 1009 Microbial <strong>Fuel</strong> <strong>Cell</strong>s 107Project 31: Building Your OwnMicrobial <strong>Fuel</strong> <strong>Cell</strong> 10810 High-Temperature <strong>Fuel</strong> <strong>Cell</strong>s 11511 Scratch-Built <strong>Fuel</strong> <strong>Cell</strong>s 121Project 32: Making Your Own MEAs 12612 Hydrogen Safety 13513 Hydrogen Transport 141Project 33: Building a Simple<strong>Fuel</strong> <strong>Cell</strong> Car 145Project 34: Building an “Intelligent”<strong>Fuel</strong> <strong>Cell</strong> Car 152Project 35: Building a Hydride-Powered<strong>Fuel</strong> <strong>Cell</strong> Vehicle 156Project 36: Building aRadio-Controlled <strong>Fuel</strong> <strong>Cell</strong>Vehicle 157Project 37: Space Travel withHydrogen! Building aHydrogen Rocket 164Project 38: Air Travel withHydrogen! Building aHydrogen-<strong>Fuel</strong>ed Airship 166Project 39: Building aRadio-ControlledAirship 16714 More Fun with Hydrogen! 169Project 40: Powering a RadioUsing Hydrogen 169Project 41: Hydrogen-<strong>Fuel</strong>ingYour iPod 171Project 42: Making HydrogenBubbles 172Project 43: Exploding SomeHydrogen Balloons 173Project 44: Having a HydrogenBarbecue 17415 <strong>Fuel</strong> <strong>Cell</strong> Competitions 177Appendix A: Everything You Wantedto Know About Hydrogen . . .and Then Some 185Appendix B: <strong>Fuel</strong> <strong>Cell</strong> Acronym Buster 187Appendix C: <strong>Fuel</strong> <strong>Cell</strong> Associations 189Epilogue 193Index 195Contentsviii
ForewordGlobal warming, depleting oil supplies, and energyindependence are all topics of discussion at dinnertables around <strong>the</strong> world. Politicians argue abouthow quickly we need to move to renewable energy,what <strong>the</strong> interim steps might be, and how we willfund <strong>the</strong> necessary new technology. Hydrogen is<strong>the</strong> most abundant, efficient energy storage devicein <strong>the</strong> universe. Converting that stored energy toelectricity will be one of <strong>the</strong> ways we willovercome some parts of <strong>the</strong> looming energy crisis.However, few people have an understanding ofhow fuel cells actually work. I have anxiouslyawaited <strong>the</strong> printing of <strong>Fuel</strong> <strong>Cell</strong> <strong>Projects</strong> <strong>for</strong> <strong>the</strong><strong>Evil</strong> <strong>Genius</strong>, so I can share it with teachers, myfriends, and colleagues around <strong>the</strong> world.Victoria Station of <strong>the</strong> London Undergroundmight seem an unlikely beginning point <strong>for</strong> a bookon hydrogen fuel cell experiments. But it was <strong>the</strong>rethat I met Gavin Harper with his arms full of anassortment of fuel cell equipment and a look ofadventure on his face. Gavin graciously guided methrough <strong>the</strong> streets of London as we searched <strong>for</strong>an elusive bottle of distilled water so that I couldtutor him in <strong>the</strong> finer points of some of <strong>the</strong> smallcells I had sent him from <strong>Fuel</strong> <strong>Cell</strong> Store. Gavinwas determined to do something about <strong>the</strong> energycrisis in his unique and meaningful fashion. Wediscussed <strong>the</strong> infant fuel cell industry, <strong>the</strong> energycrisis, and, a bit off topic, Willie Nelson. I wasimmediately struck by Gavin’s sense of wonderabout <strong>the</strong> world, and encouraged by <strong>the</strong> enthusiasmand passion with which he was approaching histask of writing a book about fuel cell experiments<strong>for</strong> students in <strong>the</strong> classroom, <strong>for</strong> hobbyists, and<strong>for</strong> <strong>the</strong> everyday person sitting at <strong>the</strong> kitchen table.It was clear that Gavin Harper was just <strong>the</strong> personto write this book. I invited him to come andwork in our small laboratory in our back offices inBoulder, Colorado where he would have accessto more equipment and some technicalassistance.Once <strong>the</strong>re, Gavin greeted us daily, showing hischeery disposition and with frequent exclamationsof joy as he found ano<strong>the</strong>r unique way to workwith hydrogen fuel cells. We were all a bit alarmedwhen he came out of <strong>the</strong> back one afternoonasking <strong>for</strong> a Band-Aid ® because he was sure hecould make a Band-Aid ® methanol fuel cell. Mystaff and I gave <strong>the</strong> “evil genius” a Band-Aid ® andsent him on his way with a wink and a nudge.A few minutes later, he came bounding from <strong>the</strong>back again—this time, to our astonishment, with aBand-Aid ® methanol fuel cell running a small fan.It is with this amazing sense of wonder, and adelightful sense of humor combined with a clearunderstanding of <strong>the</strong> workings of fuel cells that<strong>Fuel</strong> <strong>Cell</strong> <strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong> has beenwritten. Enjoy—play—discover <strong>the</strong> future ofhydrogen fuel cell energy <strong>for</strong> yourself, guided byGavin Harper’s imagination and wisdom.Kathleen (Kay) Quinn LarsonFounder/Director of Marketing<strong>Fuel</strong> <strong>Cell</strong> StoreixCopyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
AcknowledgmentsThis book would not have come into being without<strong>the</strong> generous support of Kay Larson of <strong>Fuel</strong> <strong>Cell</strong>Store. I am overwhelmed by Kay’s unceasingdevotion to promoting fuel cell technologies toyoung people. You’ll see her at many fuel cellconferences, and if you take part in <strong>the</strong> InternationalYouth <strong>Fuel</strong> <strong>Cell</strong> Competition, you are likely tobump into Kay.Also from <strong>Fuel</strong> <strong>Cell</strong> Store, I’d like to thankQuinn Larson, Matt Flood, Jason Burch, and last,but by no means least, Brett Holland <strong>for</strong> <strong>the</strong>irsupport and encouragement. It would also be verywrong not to mention H 2<strong>the</strong> cat—a fantasticcompanion to a week of fuel-cell experimentation!I also owe a great debt of gratitude to <strong>the</strong> guys at<strong>the</strong> PURE Energy Centre in Unst, in <strong>the</strong> ShetlandIslands—Dr Daniel Aklil D’Halluin, Ross Gazey,Elizabeth Johnson, and Laura Stewart. PURE areleading <strong>the</strong> way in <strong>the</strong> UK with renewable fuel celleducation.It’s great to visit PURE and see <strong>the</strong> technology thatwe are talking about in this book being implementedin <strong>the</strong> real world “on a desktop scale”—demonstrationprojects like PURE provide a great opportunity <strong>for</strong>those with an interest to go and see this technology“in <strong>the</strong> metal,” providing a glimpse into <strong>the</strong> future.I’d also like to thank Allan Jones MBE <strong>for</strong> histime and <strong>the</strong>osophy on fuel cells, all of which hashelped to shape my view that hydrogen and fuelcell technology will enable rapid change in ourenergy infrastructure.Thanks also to Tony Marmont <strong>for</strong> doing such agreat job of stimulating research and scholarlydiscourse regarding clean technologies in <strong>the</strong> UK,and <strong>for</strong> giving renewable hydrogen a real boostwith his “Hydrogen and Renewables Integration”project. Thank you to Rupert Gammon of BryteEnergy, <strong>the</strong> system architect <strong>for</strong> <strong>the</strong> HARI project,<strong>for</strong> sharing his insight about <strong>the</strong> project.Finally, <strong>the</strong>se books would never come into <strong>the</strong>world were it not <strong>for</strong> <strong>the</strong> marvelous folks behind<strong>the</strong> scenes who make <strong>the</strong>m happen. I am, as ever,indebted to Judy Bass, <strong>for</strong> giving me <strong>the</strong> chance towrite, providing encouragement, and being tolerantof my transgressions. Thanks are also due to <strong>the</strong>fabulous folk at Keyword, notably Andy Baxter,<strong>for</strong> taking my text and pictures, and turning <strong>the</strong>minto <strong>the</strong> book in front of you.xCopyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
History of Hydrogen and <strong>Fuel</strong> <strong>Cell</strong>sFigure 1-2 Robert Boyle—discovered hydrogen . . .again. Figure 1-3 Henry Cavendish—decided hydrogen waswhen it burned. Cavendish called <strong>the</strong> gas “flammableair” and published his findings in a paper titled “OnFactitious Airs.” For his endeavors, he received <strong>the</strong>Royal Society’s Copley Medal.The leap that Cavendish made was to identifyhydrogen as being different from any o<strong>the</strong>r gas.He did this by carefully measuring <strong>the</strong> density ofhydrogen, and also looking at how much wasproduced when different amounts of metal andacid reacted. This systematic, thorough inquiryhas earned Cavendish <strong>the</strong> title of <strong>the</strong> person whoultimately “discovered” hydrogen; however, this“flammable gas” was still without a name.Jacques Charles decided to employ hydrogenand put it to good use. This is <strong>the</strong> first time that wesee hydrogen in a transport application.In 1783, ten days after <strong>the</strong> Montgolfier bro<strong>the</strong>rsrose into <strong>the</strong> air with <strong>the</strong>ir hot air balloon, JacquesCharles ascended into <strong>the</strong> air in his balloon to aheight of 550 meters in his balloon “La Charlière.”He also discovered Charles’ Law which is essentiala unique substance.Figure 1-4Jacques Alexandre César Charles.2
Figure 1-5“La Charlière”.to know when looking at hydrogen storage. Thisstates that under constant pressure, a gas’s volumewill be in proportion to its temperature.Antoine Lavoisier has been called <strong>the</strong> fa<strong>the</strong>r ofmodern chemistry. Among his great accomplishments,he disproved <strong>the</strong> “phlogiston <strong>the</strong>ory,” an obsoletescientific <strong>the</strong>ory that held that in addition to whatwere <strong>the</strong>n thought of as <strong>the</strong> four elements—an ideadating back to <strong>the</strong> ancient Greeks—<strong>the</strong>re was anelement called phlogiston which was held inflammable objects, and released in varyingamounts as things burned.Lavoisier also discovered that <strong>the</strong> constituents ofwater were hydrogen and oxygen, and went a longway towards discovering <strong>the</strong> composition of <strong>the</strong>gases that make up air. He found that whenhydrogen burned in <strong>the</strong> presence of oxygen, dewwas <strong>for</strong>med. This built upon earlier observationsFigure 1-6Antoine-Laurent de Lavoisier.by Joseph Priestley. Lavoisier gave <strong>the</strong> gas <strong>the</strong>name hydrogen, which in Greek translates towater-<strong>for</strong>ming.The science of chemistry took a dramaticleap <strong>for</strong>ward with <strong>the</strong> work of John Dalton.Dalton proposed a <strong>the</strong>ory of atomic structure,and devised <strong>the</strong> first table of chemical elements,where elements were assigned relative atomicweights. This was published in his work,A New System of Chemical Philosophy. Far fromusing <strong>the</strong> common letter symbols which areused to in modern-day chemistry, Daltondevised a series of graphical symbols (as seen inFigure 1-9a).Dalton devised <strong>the</strong> symbol <strong>for</strong> hydrogen consistingof a circle enclosing a central dot (Figure 1-9b).Now we use <strong>the</strong> symbol “H,” with a smallsubscript “2,” signifying that hydrogen naturallyoccurs in a diatomic state. The Russian scientistDmitri Mendeleev (Figure 1-10), made apresentation to <strong>the</strong> Russian Chemical Society,History of Hydrogen and <strong>Fuel</strong> <strong>Cell</strong>s3
History of Hydrogen and <strong>Fuel</strong> <strong>Cell</strong>sFigure 1-7Figure 1-8Lavoisier’s apparatus <strong>for</strong> his hydrogen combustion experiment.Figure 1-9a John Dalton’s elements in “A NewJohn DaltonSystem Of Chemical Philosophy” (1808).4
Figure 1-9bDalton’s symbol <strong>for</strong> hydrogen.entitled “The Dependence between <strong>the</strong> Propertiesof <strong>the</strong> Atomic Weights of <strong>the</strong> Elements,” in whichhe arranged <strong>the</strong> elements according to <strong>the</strong>ir atomicmass. In Mendeleev’s periodic table, hydrogenadopts <strong>the</strong> symbol H.Now we move on from <strong>the</strong> history of hydrogen,to <strong>the</strong> history of <strong>the</strong> fuel cell.History of <strong>the</strong> fuel cellThe recent flurry of activity by <strong>the</strong> scientific andengineering community has brought <strong>the</strong> fuel cellinto <strong>the</strong> public eye. Many would believe that <strong>the</strong> fuelcell was a recent innovation, however, its roots canbe traced back to as early as 1838.<strong>Fuel</strong> cells are believed to be a very modern,current technology by many people: however,<strong>the</strong>ir origins can be traced back to <strong>the</strong> work ofSir William Robert Grove (Figure 1-11).Sir William Robert Grove is widely heralded as<strong>the</strong> “Fa<strong>the</strong>r of <strong>the</strong> <strong>Fuel</strong> <strong>Cell</strong>.” He was born in 1811,in Swansea, Wales. A Welsh lawyer who laterapplied himself to <strong>the</strong> mastery of science, hepublished a diagram in 1843 and made a primitivemodel known as <strong>the</strong> “Grove Gas Battery.”In <strong>the</strong> journal, Electrochemistry: History andTheory, published in 1896, Wilhelm Ostwalddescribed Grove’s gas battery (Figure 1-12) as “ofno practical importance but quite significant <strong>for</strong> its<strong>the</strong>oretical interest.”The Swiss scientist Christian Friedrich Schönbeincan be credited with discovering <strong>the</strong> underpinningprinciples behind <strong>the</strong> fuel cell’s operation. Therewere two schools of thought: <strong>the</strong> “contact” <strong>the</strong>oryand <strong>the</strong> “chemical” <strong>the</strong>ory. The contact <strong>the</strong>ory statedthat physical contact between materials generated<strong>the</strong> electricity, while <strong>the</strong> chemical <strong>the</strong>ory statedthat it was chemical reactions which generated <strong>the</strong>electricity. A furious debate ensued in <strong>the</strong> scientificHistory of Hydrogen and <strong>Fuel</strong> <strong>Cell</strong>sFigure 1-10Dmitri Ivanovich Mendeleev—Figure 1-11Sir William Robert Grove.5
Figure 1-12The Grove Gas Battery.Figure 1-14Francis Thomas Bacon.History of Hydrogen and <strong>Fuel</strong> <strong>Cell</strong>scommunity, and Grove’s correspondent Schönbeinargued <strong>for</strong> <strong>the</strong> chemical <strong>the</strong>ory.The idea of fuel cells never really developedbeyond a laboratory curiosity after this discovery;it was not really until much later, in 1959, that afuel cell with a sizable power output—5 kW—wasdeveloped by British engineer, Francis ThomasBacon (Figure 1-14).Bacon’s fuel cell used a different technologythan Grove’s earlier design. He used electrodes ofnickel in a solution of potassium hydroxide,initially calling his invention <strong>the</strong> “Bacon <strong>Cell</strong>.”Figure 1-13Christian Friedrich Schönbein.We now recognize this family of fuel cells as“alkaline fuel cells”—<strong>the</strong>re is a chapter all about<strong>the</strong>m later in this book (Chapter 6)!The first fuel cell vehicle can probably beaccredited to Harry Karl Ihrig, who built a 15 kWfuel cell tractor in 1959 (shown in Figure 1-15) <strong>for</strong>Allis-Chalmers. The alkaline fuel cell used had apotassium hydroxide electrolyte and produced20 hp power.General Electric made a bold leap <strong>for</strong>ward in <strong>the</strong>early 1960s by developing <strong>the</strong> proton exchangemembrane fuel cell. This was used in <strong>the</strong> U.S.space program in <strong>the</strong> Gemini V. The PEM fuel cellwas based on a Teflon (<strong>the</strong> material that youFigure 1-15Harry Ihrig’s fuel cell tractor.6
find on your nonstick frying pans) solidelectrolyte, which was impregnated with acid.The Apollo, Apollo–Soyuz, Skylab and Shuttlereverted back to Bacon’s design of an alkalinefuel cell.Since <strong>the</strong>se early days of <strong>the</strong> fuel cell <strong>the</strong>number of fuel cell technologies have grown, andour understanding of <strong>the</strong> material science of fuelcells has improved rapidly.A number of technology application prototypeswere developed in <strong>the</strong> 1960s by major vehicleand fuel manufacturers, to demonstrate how fuelcells could be used to provide power <strong>for</strong> transportapplications. However, <strong>the</strong> 1960s was a time ofcheap, plentiful oil when <strong>the</strong> world was not looking<strong>for</strong> a solution to future problems. The energy densityFigure 1-16 Proton exchange membrane fuel cell inGemini V, 1965. Image courtesy NASA.Figure 1-17 The alkaline “Bacon <strong>Cell</strong>s” used in <strong>the</strong>Apollo missions. Image courtesy NASA.of early fuel cells was not sufficient to allowpractical vehicles to be manufactured beyondprototypes and demonstration vehicles.In <strong>the</strong> beginning of <strong>the</strong> 1970s, <strong>the</strong>re was arenewed interest in fuel cells, driven by <strong>the</strong> widerconcern over vehicle emissions, and <strong>the</strong> damagethat vehicles were doing to <strong>the</strong> environment.The oil shocks of <strong>the</strong> early 1970s highlightedto <strong>the</strong> international community <strong>the</strong> danger of overrelianceon oil as an energy source, and peoplebegan to investigate <strong>the</strong> alternatives.Sustained development by vehicle manufacturersover <strong>the</strong> course of <strong>the</strong> 1980s meant that <strong>the</strong> internalcombustion engine’s efficiency and emissionsimproved significantly to <strong>the</strong> point where it continuedto be a viable solution. Many improvements weremade as a result of <strong>the</strong> increased control overinternal combustion engines af<strong>for</strong>ded by newelectronic engine management systems, and leanburnengines reduced many harmful emissions.However, improvements were incremental and <strong>the</strong>fundamental technology underpinning our vehicleschanged relatively little.History of Hydrogen and <strong>Fuel</strong> <strong>Cell</strong>s7
History of Hydrogen and <strong>Fuel</strong> <strong>Cell</strong>sIn 1993, Ballard Power Systems exhibited a fuelcell bus, which made important improvements onprevious fuel cell vehicle applications by showingthat higher power densities could be achieved withfuel cell technology. This has prompted a renaissanceof major interest in fuel cell technologies. In <strong>the</strong> lastdecade, with an interest in cleaner, greener ways ofdoing things, driven by concerns over peak oil,energy security, and climate change, fuel cells haveagain been in <strong>the</strong> spotlight as a potential solution tosome of our energy dilemmas.In 2003, <strong>the</strong> first public hydrogen filling stationwas opened in Reykjavik, Iceland, which serves<strong>the</strong> three hydrogen buses in <strong>the</strong> city as part of <strong>the</strong>CUTE project.With improvements in <strong>the</strong> energy density of fuelcells, it is not only <strong>the</strong> big vehicles that can nowuse fuel cell technology, but also much smallermodes of transportation. In 2005, IntelligentEnergy released <strong>the</strong> first fuel cell motorcycle,capable of travelling up to 50 mph, and with arange of 100 miles in an urban driving cycle. Itreally doesn’t make sense to transport aroundseveral tons of “dead weight” <strong>for</strong> one-passengerjourney—with questions over fuel security, wemay have to adapt, and realize that some of <strong>the</strong>most sensible solutions to problems aren’ttechnical ones, but societal ones—driving smallvehicles more fitting <strong>for</strong> our needs than our wants.So what does <strong>the</strong> near future hold <strong>for</strong> fuel cells?There are a number of fuel cell projects that areclose to completion, and appear to be technologicallyfeasible in <strong>the</strong> near term. We can already see a widerange of fuel cell applications that have emerged in<strong>the</strong> past couple of years; and with <strong>the</strong> experienceand in<strong>for</strong>mation learned from demonstrationprojects, <strong>the</strong> next generation of demonstrations willhave improved upon <strong>the</strong> current state of <strong>the</strong> art byemploying <strong>the</strong> knowledge gained. While <strong>the</strong>re isfur<strong>the</strong>r work to be done in <strong>the</strong> labs by <strong>the</strong>“materials scientists” working on improving <strong>the</strong>chemical process to convert fuel to power and tomake fuel cells longer lasting, cheaper, and morereliable, it is important that we evil geniuses do notlose sight of <strong>the</strong> fact that by creating new, novelapplications <strong>for</strong> fuel cells, we encourage investmentin <strong>the</strong> fuel cell marketplace, which brings <strong>the</strong>technology closer, quicker.<strong>Fuel</strong> cells are such a cutting edge technologythat applications are being developed <strong>for</strong> <strong>the</strong>mevery week—not just by big, well-funded industry,but equally by teams of college or universitystudents. A team called Energy Quest plans to race<strong>the</strong>ir hydrogen fuel cell powered boat, Triton, in<strong>the</strong> near future.Howaldtswerke-Deutsche Werft AG (HDW), aGerman company, has developed <strong>the</strong> Class 212submarine, a nonnuclear submarine that can remainsubmerged <strong>for</strong> weeks, without needing to come to<strong>the</strong> surface because of its PEM fuel cell technology.If you are interested in <strong>the</strong> history of fuel cells, ormaybe even need more in<strong>for</strong>mation <strong>for</strong> a schoolproject or report, <strong>the</strong>re is a rich archive ofin<strong>for</strong>mation on <strong>the</strong> Internet containing fur<strong>the</strong>rreading, on not just <strong>the</strong> low-temperature fuel cellsthat we will be experimenting with in this book,but also <strong>the</strong> high-temperature fuel cells, whichbecause of <strong>the</strong>ir high operating temperatures aren’tsuitable <strong>for</strong> home experimentation.The Smithsonians’ history of fuel cells,comprehensively covers <strong>the</strong> higher temperaturefuel cells which are not included in this book:americanhistory.si.edu/fuelcells/<strong>Fuel</strong> <strong>Cell</strong> Store’s history of fuel cells:www.fuelcellstore.com/in<strong>for</strong>mation/fuel_cell_history.htmlA history of fuel cell development at Los AlamosNational Laboratory:www.lanl.gov/orgs/mpa/mpa11/history.htm8
Chapter 2The Hydrogen EconomyYou’ve heard a little bit so far about <strong>the</strong> history ofhydrogen, and how fuel cells came into being,but why are we so interested in this gas? Whatis so special about it? Be<strong>for</strong>e we launch into <strong>the</strong>experiments, you need to be aware of why we aredoing this, and why fuel cells are <strong>the</strong> next bigthing <strong>for</strong> smart evil geniuses to be interested in.We are going to explore <strong>the</strong> physical properties ofhydrogen gas, and look at how—with fuel celltechnology—hydrogen could become a player inmeeting our future energy needs, and delivering<strong>the</strong> sustainable energy revolution.HydrogenFigure 2-1Hydrogen as it appears in <strong>the</strong> periodic table.Take a look at any periodic table, and you will findhydrogen right at <strong>the</strong> top. It is element “numerouno,” <strong>the</strong> first element in <strong>the</strong> table and <strong>the</strong> lightestof all elements. The gas is colorless, tasteless(although we don’t recommend tasting chemicals!),and nonmetallic. If you take a peek at <strong>the</strong> periodictable, you will see hydrogen in <strong>the</strong> first box to <strong>the</strong>top left (just above lithium). The box that you willsee will look something like Figure 2-1.You will see at <strong>the</strong> top of <strong>the</strong> box <strong>the</strong> number“1”—this is hydrogen’s place in <strong>the</strong> periodic table.Beneath <strong>the</strong> “1”—you’ll see “H,” <strong>the</strong> chemicalsymbol <strong>for</strong> hydrogen, and beneath this, you’ll see1.00794 this is how many grams a “mole” ofhydrogen weighs, which makes it <strong>the</strong> lightestelement.Hydrogen comprises of one “proton,” andone “electron” in its most common <strong>for</strong>m“protium”—hydrogen is a “diatomic” molecule.This means that naturally occurring hydrogen iscomprized of two atoms of hydrogen (<strong>for</strong> those ofyou who don’t know Greek, di-is a prefix meaning“two”).Looking at Figure 2-2, we can see how <strong>the</strong>re aretwo atoms that make up diatomic hydrogen. Theprotons in diatomic hydrogen occupy <strong>the</strong> twoblack dots that represent <strong>the</strong> central nuclei, while<strong>the</strong> electrons can be in any position in a “cloud”surrounding <strong>the</strong>m. This is because we cannot saywith certainty where exactly <strong>the</strong> electron will be,Figure 2-2Representation of diatomic hydrogen.Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.9
The Hydrogen Economybut we know <strong>the</strong> probability of it being a certaindistance from <strong>the</strong> nucleus. The gradient “probabilitycloud” illustrates this.At room temperature, hydrogen is a gas; infact, it boils at 20.28 Kelvin which is <strong>the</strong> sameas -252.87∞ Celsius, or -423.17∞ Fahrenheit.One of <strong>the</strong> problems is in trying to store thishydrogen in a <strong>for</strong>m that is compact—because eventhough hydrogen doesn’t weigh much, in its gaseous<strong>for</strong>m, it takes up a very large volume! Chapter 4will be looking at different ways of storinghydrogen.To give you an idea, of <strong>the</strong> difference in volumebetween liquid hydrogen and gaseous hydrogen,take a look at Figure 2-3. Hydrogen has anexpansion ratio of 1:848. This means that when itis stored as a liquid, a volume of “1 unit” of gaswill increase 848 times when allowed to expandinto a gaseous state.Hydrogen is <strong>the</strong> most abundant element in <strong>the</strong>universe, however, on Earth, <strong>the</strong>re are only 0.55parts per million by volume of hydrogen in ouratmosphere. Most of <strong>the</strong> hydrogen on Earth is lockedup in <strong>the</strong> water that makes up our seas, lakes, andrivers. The chemical <strong>for</strong>mula <strong>for</strong> water is H 2O,which means that water contains two hydrogenatoms and one oxygen atom.Our fuel cells take hydrogen fuel, and oxygenfrom <strong>the</strong> air, and produce water, releasing energyFigure 2-3The expansion ratio of hydrogen.in <strong>the</strong> process. In <strong>the</strong> process of doing so, <strong>the</strong>yrelease energy—“chemical energy.” Where doesthis energy come from?Hydrogen and oxygen, as elements, can beconsidered to be at a high energy state. Whencombined toge<strong>the</strong>r as water, <strong>the</strong>y can be consideredto have a low energy state. In <strong>the</strong> process ofcombining <strong>the</strong>m—whe<strong>the</strong>r by combustion or usinga fuel cell—<strong>the</strong> chemicals change from a highto a low energy state, but this energy must gosomewhere! (As energy is never created ordestroyed—only changed from one <strong>for</strong>m toano<strong>the</strong>r). This energy is <strong>the</strong> energy that manifestsitself as heat if we burn <strong>the</strong> hydrogen, or aselectrical energy if we use <strong>the</strong> hydrogen in a fuelcell. This change in energy states is illustrated inFigure 2-4.Now, we need to get hydrogen from somewhere.In <strong>the</strong> same way we can make water with hydrogenand oxygen, we can also make hydrogen and oxygenfrom water; however, we also need to “input”energy to disassociate hydrogen from oxygen in<strong>the</strong> process of electrolysis.Electrolysis is one of <strong>the</strong> ways that we canproduce hydrogen, and we will carry out someelectrolysis experiments later in this book.Hydrogen has <strong>the</strong> potential to be a very clean,green, fuel. In fact, it’s very easy to get into <strong>the</strong>habit of calling it a “fuel”—after all, we use it in10
Figure 2-4 Hydrogen and oxygen combine to makewater, releasing energy in <strong>the</strong> process!“fuel cells.” However, since we can’t easily gethydrogen in its elemental <strong>for</strong>m—we can’t dig it upfrom <strong>the</strong> ground—it is better thought of as an“energy carrier,” a bit like electricity is a “carrier”<strong>for</strong> energy, but not really a fuel.So, hydrogen can be a “carrier” <strong>for</strong> “cleanenergy” or it can be a carrier <strong>for</strong> “dirty energy.”We need to make an input of energy somewhereinto <strong>the</strong> process to produce hydrogen. The onlyemissions where <strong>the</strong> hydrogen is consumed is pure,clean water—no problems so far, but problems canarise if <strong>the</strong> energy we use to produce <strong>the</strong> hydrogencomes from “dirty” sources.“Green” hydrogenSo, <strong>the</strong>re are a number of ways in which we canproduce “green” hydrogen. We can use renewableenergy technologies to produce electricity, and thiselectricity can <strong>the</strong>n in turn be used to producehydrogen gas by a process called electrolysis. Wecan see this process in Figure 2-5.Let’s explore some of <strong>the</strong>se different energytechnologies in a little more detail.Solar powerWe can harness <strong>the</strong> power of <strong>the</strong> sun in photovoltaiccells. In fact, we can produce electricity usingphotovoltaic cells and feed this to a separateThe Hydrogen EconomyFigure 2-5Hydrogen produced from clean, renewable energy.11
Figure 2-6A solar array showing solar power—energy from <strong>the</strong> sun.The Hydrogen Economyelectrolyzer, or, we can use <strong>the</strong> photovoltaic cellseffectively “immersed in water,” to electrolyze <strong>the</strong>water directly. Some scientists are working ontypes of algae that can harness <strong>the</strong> sun’s energydirectly to produce hydrogen. All of <strong>the</strong>seprocesses use <strong>the</strong> sun, which is clean, free andcheap—our safest nuclear reactor—9.295 × 10 7miles away from <strong>the</strong> Earth, or if you are travellingin a hydrogen-fueled spaceship going at lightspeed(not yet invented, so watch this space), you couldbe <strong>the</strong>re in 8.31 minutes.Note: If you are interested in learning moreabout solar energy, you might like to check out myo<strong>the</strong>r publication, Solar Energy <strong>Projects</strong> <strong>for</strong> <strong>the</strong><strong>Evil</strong> <strong>Genius</strong> (McGraw-Hill).Wind powerWe can also harness <strong>the</strong> power of <strong>the</strong> wind, usingwind turbines, to produce electricity, which can<strong>the</strong>n be used to produce hydrogen cleanly. Turbinestake <strong>the</strong> movement of <strong>the</strong> air (which is caused byair rushing from an area of high pressure to anarea of low pressure) and use this <strong>for</strong>ce to turn <strong>the</strong>blades of a turbine. As <strong>the</strong> turbine blades turn, <strong>the</strong>yFigure 2-7 A wind turbine illustrating <strong>the</strong> power wecan harness from <strong>the</strong> wind.12
drive a generator; sometimes directly, sometimesthrough a gearbox. The power from this generatoris <strong>the</strong>n rectified. Once we have this electricity,we can feed it into <strong>the</strong> electricity grid that suppliesour homes, and <strong>the</strong>n use <strong>the</strong> power to electrolyzewater into hydrogen at times when <strong>the</strong> wind isblowing, but people aren’t using much electricity(as in <strong>the</strong> still of night when everyone is in bed).This makes use of cheap energy to produce ourhydrogen. Additionally, in remote islands orisolated locations, hydrogen can be used tostore electricity and even out fluctuations inload, even when <strong>the</strong>re is no connection to <strong>the</strong>electricity grid.Hydro powerThe hydrological cycle is where water evaporatesfrom <strong>the</strong> seas and <strong>the</strong> land, driven by <strong>the</strong> sun,collects in <strong>the</strong> clouds, and rains back to <strong>the</strong> ground(a process called precipitation). When <strong>the</strong> rainlands on <strong>the</strong> ground, it can land on mountains orhills, (high areas) where it must <strong>the</strong>n, under <strong>the</strong>influence of gravity, make its way back to <strong>the</strong> seas.This <strong>for</strong>ms rivers and streams all over <strong>the</strong> land. Wecan capture water when it is at a high point, channelit through a turbine or waterwheel, and captureenergy from <strong>the</strong> turbine to produce electricity. In<strong>the</strong> process of falling from a high location to alow location, <strong>the</strong> water releases gravitationalpotential energy, and it is this that we capturein a hydrostation. This hydrostation can be used toelectrolyze water into hydrogen and oxygen.Wave/tidal powerWave and tidal power are distinctly different;however, we often class <strong>the</strong>m toge<strong>the</strong>r as <strong>the</strong>y are“power from <strong>the</strong> sea.” Tidal power is a processthat is driven by <strong>the</strong> moon as it orbits <strong>the</strong> Earth.The influence of <strong>the</strong> moon’s gravity on our seascauses <strong>the</strong> water to “bulge”—this <strong>for</strong>ms <strong>the</strong> tideswhich are regular and predictable. Mariners andseafarers will know to a great degree of accuracywhen <strong>the</strong> tide is low or high, and we can use devicessubmerged in <strong>the</strong> sea to capture <strong>the</strong> mass of energyThe Hydrogen EconomyFigure 2-8Power can be captured from falling water to generate energy.13
Figure 2-9Model of a wave energy capture device.The Hydrogen Economyas water rushes from place to place. Wave power,by contrast, is <strong>the</strong> power in <strong>the</strong> surface of <strong>the</strong>waves—think of surfers riding along waves, and<strong>the</strong> energy and power that waves can exert.Devices that float on <strong>the</strong> sea or near to <strong>the</strong> surfacecan capture <strong>the</strong>se waves to turn <strong>the</strong> power intoelectrical energy and transmit it back to <strong>the</strong> shore.In both <strong>the</strong>se instances, when <strong>the</strong> power reaches<strong>the</strong> shore, it can be used to electrolyze water intohydrogen and oxygen.Geo<strong>the</strong>rmal powerGeo<strong>the</strong>rmal energy, energy from <strong>the</strong> heat in <strong>the</strong>core of <strong>the</strong> Earth, can be used to raise steam todrive conventional steam turbines to produceelectricity, which can be used to provide hydrogen.BiomassAll <strong>the</strong> living things that we are surrounded by—<strong>the</strong>trees and plants and crops that grow in farmers’fields—are a mass of biological matter. The sundrives a process called photosyn<strong>the</strong>sis in plants,Figure 2-10 A plume of hot water, driven out of <strong>the</strong>ground by geo<strong>the</strong>rmal energy.which enables <strong>the</strong>m to take carbon dioxide out of<strong>the</strong> air, combine it with hydrogen and oxygen fromwater to make food to nourish <strong>the</strong> plant, and allowit to grow. We can take biomass, and turn it intofuels—biodiesel, bioethanol, but we can alsoextract <strong>the</strong> hydrogen directly from biomass, suchas <strong>the</strong> woodchip waste shown in Figure 2-11, usingFigure 2-11Biomass—power from plants.14
gasification and re<strong>for</strong>mation processes, similar tothose used to extract hydrogen from fossil fuels. Thisdoes produce carbon dioxide; however, <strong>the</strong> onlycarbon dioxide produced is that which has beenextracted from <strong>the</strong> atmosphere by <strong>the</strong> plant as itgrew!“Dirty” hydrogenAt <strong>the</strong> moment, most of our hydrogen is producedusing “dirty” methods. Fossil fuels, coal, oil, andnatural gas, are taken and “re<strong>for</strong>med” into hydrogen.However, fossil fuels also contain a high proportionof carbon. This carbon has to go somewhere—aspart of <strong>the</strong> re<strong>for</strong>mation process, <strong>the</strong> byproduct,“carbon dioxide,” is produced. Carbon dioxide is agreenhouse gas which adds to <strong>the</strong> “greenhouseeffect,” which leads to <strong>the</strong> problems that we arebeginning to witness with global warming andclimate change.Coal, oil, and gas can all be taken and turned intohydrogen using a process called steam re<strong>for</strong>mation,which takes <strong>the</strong> fossil fuels, combines <strong>the</strong>mwith steam at pressure and very high temperature,stripping <strong>the</strong> carbon, producing carbon dioxide,and capturing <strong>the</strong> hydrogen <strong>for</strong> use in fuel cellvehicles. Natural gas contains <strong>the</strong> highest ratioof hydrogen to carbon. If you think about methaneand its chemical structure (CH 4), <strong>the</strong>re are fourhydrogen atoms <strong>for</strong> every carbon atom. Look atoil, and <strong>the</strong> amount of carbon relative to hydrogenincreases—take petrol, which contains manydifferent lengths of hydrocarbon chain—but wecan approximate to octane, and you see <strong>the</strong> ratio ofhydrogen to carbon is nearer: 1:2 (C 8H 18) whilemethane is 1:4. Start to look at coal, and <strong>the</strong> storybegins to get even more grim—as coal is largelycomprized of carbon, <strong>the</strong>re is much more carbondioxide produced than hydrogen.Alternatively, we can burn fossil fuels in aconventional fossil fuel power station, like <strong>the</strong> one inFigure 2-13, and use that electricity <strong>for</strong> electrolysis.However, although this is very undesirable, it isnot all totally bad news. Compare producinghydrogen in this way to burning <strong>the</strong> fuels directlyin your vehicles and over a range of scatteredlocations. By producing hydrogen, you are makingall of <strong>the</strong> carbon dioxide in a central location,where it can be captured. Once we have separatedand captured <strong>the</strong> carbon dioxide, we don’t justhave to release it into <strong>the</strong> atmosphere; we can doclever things with it—like trap it, and contain it.A process called carbon sequestration can beused to take carbon dioxide, and inject it deepunderground, into geological features, where<strong>the</strong> CO 2is trapped and (touch wood) cannotescape.The Hydrogen EconomyFigure 2-12Hydrogen produced from dirty fossil fuels.15
Figure 2-13Fossil fuel power stations can generate hydrogen to produce electricity.The large oil and energy interests find thistechnology very attractive. The reason <strong>for</strong> this hasless to do with altruism and <strong>the</strong> preservation of <strong>the</strong>human race, and more to do with oil and profits.By <strong>for</strong>cing carbon dioxide into oil wells which arenearing <strong>the</strong> end of <strong>the</strong>ir economic life, <strong>the</strong> carbondioxide can be used to <strong>for</strong>ce additional oil to <strong>the</strong>surface, recovering deposits of oil that wouldo<strong>the</strong>rwise go to waste.The Hydrogen EconomyFigure 2-14 The products of combustion from fossilfuel plants like this could be captured and sequestered.Nuclear hydrogenSome people advocate a hydrogen economy basedupon hydrogen produced en masse by nuclearpower. We can see by looking at Figure 2-15 thatnuclear power is used to produce electricity, whichin turn is used to convert water to hydrogen byelectrolysis.Un<strong>for</strong>tunately, <strong>the</strong> byproduct of this processis toxic, radioactive nuclear waste, which takesthousands of years to decay to safe levels—and westill haven’t worked out a permanent solution <strong>for</strong>what to do with it!The reason that some people advocate nuclearpower is that no carbon emissions are producedby <strong>the</strong> actual process of producing electricity fromnuclear fuel. However, take into consideration<strong>the</strong> massive amounts of concrete and building16
Figure 2-15Hydrogen produced from nuclear power.materials needed to build a nuclear plant, consider<strong>the</strong> carbon dioxide produced in blasting, mining,extracting, refining, transporting, storing, andprocessing nuclear fuel, and suddenly you realizethat <strong>the</strong>re is an awful lot of hidden carbon dioxidein this process.Fur<strong>the</strong>rmore, once <strong>the</strong>ir useful life has finished,nuclear power stations, like <strong>the</strong> one in Figure 2-16,need to be decommissioned—a process whichrequires a great amount of money, and a greatinvestment of energy—with its associated carbonemissions.The Hydrogen EconomyFigure 2-16Nuclear power stations leave an ugly blot on <strong>the</strong> landscape.17
The Hydrogen EconomyThe need <strong>for</strong> cleanertechnologiesSince <strong>the</strong> Industrial Revolution, through <strong>the</strong> oilboom of <strong>the</strong> 1960s, <strong>the</strong> human race’s burgeoningneed <strong>for</strong> energy has resulted in a rise of carbondioxide emissions globally.A monitoring station on <strong>the</strong> Island of MaunaLoa, in remote Hawaii, has been monitoring<strong>the</strong> levels of carbon dioxide since <strong>the</strong> mid-1950s.The results are displayed as a graph inFigure 2-17.It is clear to see that since <strong>the</strong> 1950s, <strong>the</strong> level ofcarbon dioxide in our atmosphere has continuallyand steadily increased.“But how do we know that <strong>the</strong>re wasn’t thismuch carbon dioxide in <strong>the</strong> atmosphere be<strong>for</strong>e1955?” some people counter. Well, in addition totaking measurements of carbon dioxide from <strong>the</strong>atmosphere, it is also possible to drill great coresof ice from <strong>the</strong> Antarctic. This ice has been <strong>for</strong>medover many, many years, as snow deposited itself onFigure 2-17CO 2measurements taken at Mauna Loa.top of <strong>the</strong> existing shelf, trapping little pockets ofgas. We can analyze <strong>the</strong>se pockets of gas to findout an abundance of data about what our climatewas like at different times.If you want to read more about ice cores, <strong>the</strong>re isa comprehensive and in<strong>for</strong>mative article onWikipedia: en.wikipedia.org/wiki/Ice_coresSo, why have carbon dioxide emissions recentlyshot up?The growth of our economies has been foundedon cheap oil, and <strong>the</strong> perception that “<strong>the</strong>world’s resources are endless.” As we begin tofind resource shortages, we will quickly begin torealize that <strong>the</strong> Earth’s resources are indeedfinite.Ever since <strong>the</strong> Industrial Revolution, our demand<strong>for</strong> fossil fuels, and o<strong>the</strong>r resources has grown.Looking at Figure 2-18, we can see how suddenlyman-made (anthropogenic is a word you willoften hear used) emissions have soared rapidly. Infact, most of <strong>the</strong>se emissions were created in <strong>the</strong>past century.Think of all <strong>the</strong> things that we can do in thiscentury, which wouldn’t have been possiblelast century, or even decades ago. Think about<strong>the</strong> massive amount that we use our cars. Massproduction has enabled everyone in <strong>the</strong> developedworld to be able to own a car should <strong>the</strong>y choose.We have seen <strong>the</strong> growth in numbers of familieswith not just one but many cars. All <strong>the</strong>se vehiclesrequire energy to be made, and in use. Look ataviation as ano<strong>the</strong>r growth sector. Fifty years ago,aviation was expensive, <strong>for</strong> <strong>the</strong> elite, but now itis possible to fly so incredibly cheaply that <strong>the</strong>number of flights taken has soared (literally) into<strong>the</strong> sky!18
Figure 2-18Global fossil fuel carbon emissions since <strong>the</strong> Industrial Revolution.So what’s <strong>the</strong> problem?Well, <strong>the</strong> first one is climate change. If you haven’talready seen Al Gore’s “An Inconvenient Truth,” itis a great primer on climate change <strong>for</strong> evil geniusesof all ages. The carbon dioxide that we producewhen we burn fossil fuels is one of <strong>the</strong> gases thatcontributes to a phenomenon called “<strong>the</strong> greenhouseeffect” which produces global warming.Looking back to earlier in this chapter, you willremember that <strong>the</strong>re are “clean ways” in which wecan produce hydrogen, without producing anycarbon dioxide emissions in <strong>the</strong> process. Ofcourse, at <strong>the</strong> moment, our technologies andinfrastructure are geared towards a carbon-basedeconomy. At <strong>the</strong> moment, most of our hydrogenavailable <strong>for</strong> use in fuel cells comes from carbonbasedfuels, however, with future development ofrenewable energy resources, <strong>the</strong> hydrogeneconomy offers some attractive prospects <strong>for</strong> aworld moving toward a cleaner future.The thing is, it isn’t just <strong>the</strong> countries that arealready developed that are going to require energy.While <strong>the</strong> energy demands of America and Europecontinue to grow, we must also think of developingcountries such as China and India, whose economiesare growing rapidly. With this rapid growth comesincreased demand on resources and energy.And <strong>the</strong>re’s ano<strong>the</strong>r reason <strong>for</strong> looking athydrogen: you might have noticed that <strong>the</strong> price ofgas at <strong>the</strong> pumps has been increasing significantlyrecently. Chances are that from here onward pricesaren’t going to come down significantly <strong>for</strong> anylong period of time.A scientist from <strong>the</strong> American Petroleum Institute,Marian King Hubbert, made a prediction in 1956that oil discoveries would follow a bell-shapedcurve. Take a look at Figure 2-19, as we are going tolook through <strong>the</strong> features of <strong>the</strong> graph.Peak oil is an important subject to read up on, <strong>for</strong>any budding evil genius interested in fuel celltechnology. Wikipedia carry some good articleson this, which I highly recommend:en.wikipedia.org/wiki/Peak_oilen.wikipedia.org/wiki/Hubbert_peak_<strong>the</strong>oryThe Hydrogen Economy19
Figure 2-19Hubbert’s peak oil bell-shaped graph.production—peak oil—which means from here<strong>for</strong>ward, oil starts getting a lot harder to find. As aresult of <strong>the</strong> increased ef<strong>for</strong>t that needs to beexpended to find new oil, <strong>the</strong> price will begin tosoar. Ra<strong>the</strong>r than being cheap and plentiful, oil willstart to become more expensive, as it becomesharder and harder to find and produce. The pricebegins to rise, and rise, and rise, while <strong>the</strong> actualamount of oil entering <strong>the</strong> system begins todecline. Now, remember, we don’t just need oil <strong>for</strong>transportation, we also use oil in <strong>the</strong> production ofpharmaceuticals, plastics, paints, and variousfinishes, so we don’t want to spend all of ourbudget of oil on transportation and producingenergy—this could be where hydrogen and fuelcell technology enter <strong>the</strong> arena.The Hydrogen EconomyHubbert said that <strong>for</strong> any geographical area—whe<strong>the</strong>r a single oil field, <strong>the</strong> oil reserves of astate, nation or continent—or ultimately <strong>the</strong> entireworld, <strong>the</strong> rate at which oil was discovered wouldfollow what is called a bell-shaped curve. If youlook at Figure 2-19, you can see that <strong>the</strong> areaenclosed beneath <strong>the</strong> line sort of resembles a crudedrawing of a church bell.Looking at <strong>the</strong> beginning of this curve, we seethat when oil was initially discovered, it wasn’tproduced in great profusion, as people werestill finding applications <strong>for</strong> it, and investing ininfrastructure to produce and refine it. As we slowlydiscovered how darn useful oil actually was,people began to consume more of it, which in turndrove <strong>the</strong> production of oil. With <strong>the</strong> invention of<strong>the</strong> internal combustion engine, and <strong>the</strong> spread of<strong>the</strong> motor car, our consumption of oil has soared(with a massive increase in carbon emissions as aresult). However, this growth is not without limits.There is a finite amount of oil in <strong>the</strong> Earth’s crust.We have found all <strong>the</strong> oil that is “easy todiscover,” <strong>the</strong> oil that is in <strong>the</strong> accessibleplaces that can be easily and cheaply reached.We are now approaching <strong>the</strong> “peak” of oilWhy hydrogen?The ways that we currently “extract” energy fromfossil fuels are pretty wasteful. If we look at Figure2-20, we can see a range of different devices thatwe use <strong>for</strong> producing useful energy from fuels. Wecan see that fuel cells, over a whole range ofpowers, eclipse <strong>the</strong> efficiency of even <strong>the</strong> besthybrid solutions and turbine applications.Figure 2-20compared.Technologies <strong>for</strong> converting energy20
The barrier at <strong>the</strong> moment is twofold:●●TechnologyPrice<strong>Fuel</strong> cells work well in <strong>the</strong> lab, but as soonas we start to take <strong>the</strong>m and put <strong>the</strong>m intoapplications, we have to overcome practicalproblems concerned with <strong>the</strong> technology. Ourhydrogen is very light, but it takes up an enormousvolume—as a result, we have to look at ways topractically store <strong>the</strong> hydrogen <strong>for</strong> use in ourvehicles and o<strong>the</strong>r applications. Ano<strong>the</strong>r is <strong>the</strong>lifespan of fuel cells. Everything in this worldwears out sooner or later—<strong>the</strong> first combustionengines would have been unreliable affairs—with<strong>the</strong> technology being improved over time. Withfuel cells, <strong>the</strong> technology is gradually improving.We are coming to <strong>the</strong> end of <strong>the</strong> initial “researchand development” phase, and we are starting to seefuel cell technology with sufficient durability to beable to enter commercial applications.Remember, <strong>the</strong>re aren’t any moving parts withhydrogen and fuel cells, so <strong>the</strong>re isn’t anythingmechanical to go wrong. Fur<strong>the</strong>r improvementsneed to be made, but step by step, <strong>the</strong> technologyis getting <strong>the</strong>re. For vehicles in cold climates,<strong>the</strong> cold-start per<strong>for</strong>mance of fuel cells has hadto improve, but again this shows signs ofimprovement. Fur<strong>the</strong>rmore, manufacturers arelearning how to get more power from smaller andsmaller fuel cells, and we will look at some of <strong>the</strong>technology developments in this book. As fuelcells shrink, <strong>the</strong>re is more room <strong>for</strong> o<strong>the</strong>r vehiclecomponents, and hydrogen storage, so we seemore applications <strong>for</strong> <strong>the</strong> technology. Aside from<strong>the</strong> technology, we need to look at <strong>the</strong> price. Forfuel cells that employ PEM technology, platinum,<strong>the</strong> catalyst, as we will see, is a very important partof <strong>the</strong> chain of events, making <strong>the</strong> reactions in <strong>the</strong>fuel cell happen. I don’t know if you’ve browsedany jewellers recently, but platinum is prettyexpensive stuff. It really isn’t cheap! This is one of<strong>the</strong> barriers to <strong>the</strong> development of fuel cellscommercially, but gradually <strong>the</strong> requirement <strong>for</strong>Figure 2-21<strong>Fuel</strong> cell technology trends in vehicles.platinum in fuel cells has being steadily reducing.This and o<strong>the</strong>r improvements to <strong>the</strong> technology willmean that fuel cells will become cheaper—andas <strong>the</strong>y do so, <strong>the</strong>y will become more af<strong>for</strong>dableto you and I, finding more applications in <strong>the</strong> realworld.Look at Figure 2-21, and you will see some of<strong>the</strong> major technology trends <strong>for</strong> fuel cell technologyin vehicles. You can see where <strong>the</strong> technologyhas come from, and where it is expected to go by2010.We looked earlier at all <strong>the</strong> different possiblemethods of producing hydrogen—as <strong>the</strong>technology becomes cheaper and more attractive,we can envisage an energy economy based onrenewable energy and clean energy sourcesgenerating electricity to produce hydrogen, withthis hydrogen being used as a carrier <strong>for</strong> <strong>the</strong> cleanenergy.If you look at <strong>the</strong> Figure 2-22, you can see howa prospective hydrogen economy could work.Of course, <strong>the</strong> advantage, as you can see, is thatwith clean energy and hydrogen, carbon dioxideand toxic pollutants are eliminated from <strong>the</strong> process,with <strong>the</strong> only things entering and exiting to andfrom <strong>the</strong> natural environment being water andoxygen. We can see this in Figure 2-23, hydrogenand oxygen being <strong>the</strong> constituents of water.The Hydrogen Economy21
Figure 2-22Prospective hydrogen economy.Work through <strong>the</strong> projects in this book and youwill begin to understand <strong>the</strong> technology, but all <strong>the</strong>time throughout your experimentation, relate <strong>the</strong>practical things that you are doing to what ishappening in <strong>the</strong> real world outside <strong>the</strong> lab. Thinkabout and visualize how <strong>the</strong> technology that youFigure 2-23Hydrogen, oxygen and water.are working with has <strong>the</strong> potential to change <strong>the</strong>world <strong>for</strong> <strong>the</strong> better. When thinking about <strong>the</strong>technology, reading articles in newspapers andmagazines, and talking to your friends and family,always keep a sound grasp of <strong>the</strong> issues—thinkabout how clean hydrogen can be a <strong>for</strong>ce <strong>for</strong> good,and when you hear of hydrogen being generatedfrom dirty sources, read between <strong>the</strong> lines andthink about whe<strong>the</strong>r <strong>the</strong> strategies proposed reallyare environmentally sound.The Hydrogen Economy22
Chapter 3Producing HydrogenSo where do we gethydrogen from?There are a number of ways that we can get ourhydrogen. It is a bit of a myth that hydrogen is a“fuel”—it isn’t really as <strong>the</strong>re is no such thing as ahydrogen mine or a hydrogen well—we can’t justdig it out of <strong>the</strong> ground or drill <strong>for</strong> it like oil or gas.We need to produce it from ano<strong>the</strong>r primary energysource. In this chapter we are going to evaluate someof <strong>the</strong> different options <strong>for</strong> producing hydrogen.ElectrolysisAt school, you might have used a Hoffmanapparatus in science class. A Hoffman apparatushas a reservoir of water through which is passed anelectric current. The electric current disassociates<strong>the</strong> hydrogen from <strong>the</strong> oxygen in <strong>the</strong> water. Thegas bubbles off from <strong>the</strong> electrodes and is collectedin separate storage containers. It is observed thattwice as much hydrogen is produced as oxygen.Taking a little bit of time to think about this, wesee that <strong>the</strong> chemical <strong>for</strong>mula <strong>for</strong> water is H 2O—thismakes sense as we can see that <strong>the</strong>re is twice asmuch hydrogen in water than oxygen.The hydrogen produced by <strong>the</strong> electrolysisprocess is very pure—some fuel cells require avery pure <strong>for</strong>m of hydrogen so this is ideal.The one disadvantage of electrolysis is that significantamounts of electrical energy are needed <strong>for</strong><strong>the</strong> process. While this electricity can be generatedusing clean, green renewable energy, <strong>the</strong>re are alsomany champions of a nuclear-hydrogen economyusing supposedly cheap nuclear energy to producehydrogen—this would leave us with a toxic legacyof waste, and would negate many of <strong>the</strong> benefits ofa clean hydrogen economy.Biomass gasificationand re<strong>for</strong>mationBiomass has proven itself as a relatively clean,near carbon-neutral source of energy. Agriculturalwaste, organic matter, wood, and o<strong>the</strong>r sources ofbiomass can be heated in a controlled atmospherewithout <strong>the</strong> presence of oxygen. This yields agas—syn<strong>the</strong>sis gas—which is hydrogen-rich aswell as containing carbon monoxide and dioxide.The carbon emissions from this source of energyare effectively neutral as <strong>the</strong> carbon dioxide wastaken out of <strong>the</strong> atmosphere in <strong>the</strong> first place by <strong>the</strong>growing plants, however, carbon emissions in <strong>the</strong>production and distribution of biomass cannot beignored. There is also <strong>the</strong> possibility of sequestering<strong>the</strong> carbon produced in <strong>the</strong> gasification process.This could effectively make biomass with hydrogenextraction a “carbon-negative” fuel.Steam re<strong>for</strong>mationBy combining high-temperature steam, andmethane, it is possible to extract hydrogen fromthis fossil fuel. Although carbon dioxide is produced,<strong>the</strong> location is centralized and it opens up <strong>the</strong>possibilities <strong>for</strong> carbon sequestration (althoughbear in mind that this is an unproven technologywith no demonstrated long-term safety). The process23Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
is fairly cheap and inexpensive, and <strong>the</strong> heat producedcan also be harnessed (known as cogeneration).Cogeneration provides us with lots of low-levelheat which could prove useful in local combinedheat and power schemes. This method does show alot of promise, as it is currently an efficient cheaptechnology that will work with <strong>the</strong> existing gasdistributioninfrastructure; however, <strong>the</strong> carbonemissions are impossible to ignore.Clean coal?There are vast tracts of coal throughout <strong>the</strong> world;however, coal is carbon-rich—burning it doesn’<strong>the</strong>lp global warming, and mining leaves scars on<strong>the</strong> landscape, which can last <strong>for</strong> generations. Thereare, however, schemes afoot to look at gasifyingcoal, extracting <strong>the</strong> carbon, and sequestering it.Project 1: Testing <strong>for</strong> HydrogenPhotoelectrolysisPhotoelectrolysis is a relatively new unproventechnology. It involves using solar energy to stimulatea silicon junction similar to a photovoltaic cell,with <strong>the</strong> distinction that instead of <strong>the</strong> energybeing converted to electricity, <strong>the</strong> silicon junctionacts directly on <strong>the</strong> water where electrolysis occurs.This technology shows promise, although muchdevelopment must be done.In this chapter, we are going to look at how toproduce hydrogen. But once you’ve produced agas, how do you know what it is? Here we aregoing to show a simple test <strong>for</strong> hydrogen.●●●24Test tube of gas under testWooden splintSource of flame (e.g., candle)MethodHydrogen is a colorless, odorless gas, which isincredibly flammable, and combines with oxygenBiologically producedhydrogenThere are a number of types of algae that usephotosyn<strong>the</strong>sis to convert solar energy intohydrogen. At <strong>the</strong> moment, <strong>the</strong>se processes haveonly been demonstrated on a small scale, butresearch in this area is intense. It is expected thatgreat strides <strong>for</strong>ward could be made in this area.Project 1: Testing <strong>for</strong> Hydrogento <strong>for</strong>m water. The mixture is so explosive that justa single spark will make it explode! We can usethis property to help us test <strong>for</strong> its presence!There is a really simple, if a little loud, experiment.Take a test tube of <strong>the</strong> gas which you believe tobe hydrogen. Take a lighted splint of wood, andintroduce it into <strong>the</strong> container. The hydrogen shouldproduce a loud squeaky pop as shown in Figure 3-1.Figure 3-1The test <strong>for</strong> hydrogen.
Check out some videos of hydrogen explosions!!!Look at <strong>the</strong> *.mpeg “hydrogen gas”smartweed.olemiss.edu/nmgk12/curriculum/curr_eighth.htmHere, a balloon full of hydrogen gas is lit!pk014.k12.sd.us/chemistry/chapter%20two/hydrogen_balloon.mpgOne of <strong>the</strong> things that you can do is per<strong>for</strong>m thisexperiment near a piece of dry glass that hasbeen chilled. You should see a frosting on <strong>the</strong>glass—this frosting is water.ConclusionHydrogen is an explosive gas which will easilyignite. Its flammability is one of <strong>the</strong> reasons thatwe tend to use helium ra<strong>the</strong>r than hydrogen innovelty balloons. When hydrogen burns in air, itcombines with oxygen and <strong>the</strong> product is water.We can write this as a word equation, as inEquation 3-1Word equation <strong>for</strong> hydrogen burning (Equation 3.1):We can see that hydrogen (in our test tube), andoxygen (in <strong>the</strong> air) combine to make water (<strong>the</strong>frosting we saw on <strong>the</strong> glass).If we want to be more sophisticated scientists,we can take this word equation, and turn it into a“chemical” equation, where we substitute <strong>the</strong>words <strong>for</strong> chemical symbols. You can see inEquation 3-2, how “H” represents hydrogen, and“O” oxygen, with <strong>the</strong> chemical <strong>for</strong>mula <strong>for</strong> waterH 2O. The symbols in brackets after each chemicaldenote <strong>the</strong> state of <strong>the</strong> chemical—solid, liquid, gasor dissolved in water.Chemical equation <strong>for</strong> hydrogen burning(Equation 3-2):State symbolsHere’s a handy reference of state symbols <strong>for</strong>you. Remember, we use “l” <strong>for</strong> water, as it is aliquid, but when something is dissolved in water,we use <strong>the</strong> symbol “(aq)” to represent “aqueoussolution.”(s) = solid(l) = liquid(g) = gas(aq) = aqueous solution (dissolved in water)However, <strong>the</strong> astute ma<strong>the</strong>maticians among youwill quickly notice that things don’t quite add up.Looking at <strong>the</strong> amounts of hydrogen and oxygen,and <strong>the</strong> amounts of water produced, we appear tohave lost an oxygen atom somewhere, as <strong>the</strong>re aretwo atoms in one molecule of hydrogen. There<strong>for</strong>e,we need to balance <strong>the</strong> equation. Two lots ofhydrogen will combine with one lot of oxygen tomake two lots of water. We can show this byprefixing <strong>the</strong> “Hs” with a “2” to denote how manylots. This is shown in Equation 3-3.Balanced chemical equation <strong>for</strong> hydrogen burning(Equation 3-3):You are going to come across balance equationsa lot in this book, so get to grips with <strong>the</strong>m now.Just remember that <strong>the</strong> big number in front showshow many lots of something <strong>the</strong>re are, while <strong>the</strong>little subscript numbers show how many atoms<strong>the</strong>re are of an element in each lot.Project 1: Testing <strong>for</strong> Hydrogen25
Project 2: Testing <strong>for</strong> Oxygenthat you suspect is oxygen right away (Step 3). If<strong>the</strong> gas is oxygen, <strong>the</strong> splint will quickly relight(Step 4).Project 2: Testing <strong>for</strong> Oxygen●●●Test tube of gas under testWooden splintSource of flame (e.g., candle)MethodOxygen is <strong>the</strong> only gas that will support burning,so we can use this property to test <strong>for</strong> its presence.To test <strong>for</strong> oxygen, take a test tube of <strong>the</strong> gas thatyou want to test. The procedure <strong>for</strong> this test isillustrated in Figure 3-2Ensure that <strong>the</strong> end of <strong>the</strong> tube is ei<strong>the</strong>r sealed orimmersed under water to prevent <strong>the</strong> gas fromescaping. Now, take a wooden splint and light it(Step 1), blow it out (Step 2)—you should makesure that <strong>the</strong> end of <strong>the</strong> splint glows—<strong>the</strong>re mightbe a little wisp of smoke where it is smouldering,but it should not be lit. Now dip it into <strong>the</strong> test tubeFigure 3-2The test <strong>for</strong> oxygen.Oxygen factoidOxygen is pH neutral—it will not have any effecton litmus or indicator paper.ConclusionWe have seen how oxygen is essential <strong>for</strong> burningto take place, and how burning is much easier in anenvironment of pure oxygen, than in air, whichcontains only 21% oxygen. This is evidenced by<strong>the</strong> fact that <strong>the</strong> splint was only glowing in <strong>the</strong> air;however, once inserted into <strong>the</strong> test tube of oxygen,it began to burn brightly.We will see later on, with our fuel cells, how<strong>the</strong>y operate much better with pure oxygen thanwith ordinary air.26
There are a lot of different ways in which we canproduce hydrogen—<strong>the</strong>se are going to be investigatedin this chapter. One way of producing hydrogen,that is convenient using readily accessiblematerials in a laboratory, is by reacting an acidwith metal. We are going to carry out thisexperiment to produce hydrogen, and <strong>the</strong>n look at<strong>the</strong> chemistry that is taking place.●●●●●Thistle tubeSwan neck tubeGas jarBowlTimerMethodProject 3: Investigating Acid–Metal ReactionsYou are going to need to set up <strong>the</strong> apparatus asshown in Figure 3-3. Be careful with <strong>the</strong> thistletube, swan neck tube, and flask as <strong>the</strong>y are madefrom delicate glass.As your reaction proceeds, use a timer and takemeasurements of <strong>the</strong> volume of gas producedfrom <strong>the</strong> marks on <strong>the</strong> gas jar. Table 3-1 has beenprovided <strong>for</strong> your convenience to note yourresults down.ConclusionIn a reaction involving a metal, <strong>the</strong> metal reacts bylosing one or more electrons. This loss of electronsis called “oxidization” by chemists; we can rankmetals according to how easily <strong>the</strong>y oxidize; <strong>the</strong>more easily <strong>the</strong>y oxidize, <strong>the</strong> more active we saythat <strong>the</strong>y are. The activity series <strong>for</strong> metals isshown in Figure 3-6. Hydrogen is shown on thislist as a reference point (although remember it is anonmetal).At <strong>the</strong> same time as oxidization is taking place,it is always accompanied by a reduction ofmaterials. Reduction is where a chemical gainselectrons.Project 3: Investigating Acid–Metal ReactionsFigure 3-3Producing hydrogen from acid and metal.27
Table 3-1Results from acid–metal reaction.Project 3: Investigating Acid–Metal ReactionsTimeHydrogen produced(seconds) (cm 3 )s cm 3s cm 3s cm 3s cm 3s cm 3s cm 3s cm 3s cm 3s cm 3s cm 3Remember that oxidation is always accompaniedby reduction by using this simple little diagram.A nice way to remember this is illustratedin Figure 3-5—this is a diagram you’ll comeinto contact with later in this book! Remember<strong>the</strong> words LEO and GER using <strong>the</strong> simplemnemonic—LEO <strong>the</strong> Lion goes GER—LossEquals Oxidation, Gain Equals Reduction.Figure 3-4 Reduction, oxidization—like Starsky andHutch, you can’t have one without <strong>the</strong> o<strong>the</strong>rFigure 3-5 LEO <strong>the</strong> Lion will help you to rememberredox reactions by going GER.So what’s happening here?The hydrogen ions in <strong>the</strong> acid migrate to <strong>the</strong> metalsurface. Hydrogen ions in <strong>the</strong> acid accept electronsfrom <strong>the</strong> metal surface (and <strong>the</strong> metal surface givesup electrons). The hydrogen ions combine with <strong>the</strong>electrons to make hydrogen atoms. Hydrogen atomscombine to give hydrogen molecules. Rememberfrom Chapter 2 that with hydrogen it takes“two atoms to tango,” as it is diatomic. Metalions hydrate and move away from <strong>the</strong> metalsurface.You will notice that <strong>the</strong> production of hydrogengas eventually slows down and halts. As <strong>the</strong> reactantsare consumed, <strong>the</strong> rate of hydrogen productiondeclines until all <strong>the</strong> reactants are used up—and<strong>the</strong>n <strong>the</strong> reaction stops.Taking it fur<strong>the</strong>rWe are going to be hearing a lot in this bookabout catalysts, so you might as well get usedto <strong>the</strong>m sooner ra<strong>the</strong>r than later! The productionof hydrogen using zinc and sulfuric acid was28
eally quite slow. If we wanted to increase <strong>the</strong>rate of reaction, a good way to do this wouldbe to use a catalyst, a chemical which facilitates<strong>the</strong> reaction and enables it to proceed at afaster rate.You can add a little copper (II) sulfate toyour zinc, and that will speed up <strong>the</strong> rate ofhydrogen production. You should alreadyhave some data about <strong>the</strong> reaction rate of zinc.Try adding a little catalyst, and see how it affects<strong>the</strong> rate of reaction. Note your resultsin Table 3-2.Compare <strong>the</strong> gas produced over time in Table 3-1with Table 3-2 when <strong>the</strong> catalyst is added . . .Interesting?Table 3-2Comparing <strong>the</strong> reactions with and withoutcatalysts.Time With CuSO 4Without CuSO 4(seconds) catalyst catalysts cm 3 cm 3s cm 3 cm 3s cm 3 cm 3s cm 3 cm 3s cm 3 cm 3s cm 3 cm 3s cm 3 cm 3s cm 3 cm 3s cm 3 cm 3s cm 3 cm 3Project 4: Investigating <strong>the</strong> Activity of Metals WhenProducing HydrogenAs <strong>for</strong> <strong>the</strong> previous project plus different metalsamples, e.g.:●●●●●●MagnesiumAluminum/aluminiumZincIronTinLeadMethodPotassium, sodium, lithium, and calcium all reactviolently with dilute sulfuric acid and dilutehydrochloric acid. It is dangerous to put <strong>the</strong>semetals into an acid.Project 4: Investigating <strong>the</strong> Activity of Metals29
Project 4: Investigating <strong>the</strong> Activity of MetalsWe want to try and eliminate as many “strayvariables” as we possibly can, by ensuring that asmany things are <strong>the</strong> same as possible. Whenselecting your metal scraps, try and look <strong>for</strong>scraps which are as near as possible <strong>the</strong> sameshape and size—as we want to try and ensure that<strong>the</strong> surface area available <strong>for</strong> reaction is <strong>the</strong> same<strong>for</strong> all <strong>the</strong> metal samples. (This has an impact on<strong>the</strong> rate of reaction.)We are going to repeat <strong>the</strong> previous project;however, this time, we are going to use differentmetals each time. We want to pick a selection ofTable 3-3Measure <strong>the</strong> activity of different metals.scraps that are all roughly <strong>the</strong> same size and have<strong>the</strong> same surface area. We are going to takemeasurements with our timer and graduated gasjar, and note <strong>the</strong>m in Table 3-3.ConclusionWhat did you notice? You should have seenthat some metals produced hydrogen gasvery quickly, while some took <strong>the</strong>ir time toproduce gas—<strong>the</strong> metals reacted with <strong>the</strong>acid at different rates, i.e., <strong>the</strong>ir reactivity wasdifferent.We can place metals into what is called a“reactivity series”—this allows us to classify howvigorously different metals will react with air,water, and acids.TimeAluminum/(seconds) Magnesium aluminium Zinc Iron Tin Leads cm 3 cm 3 cm 3 cm 3 cm 3 cm 3s cm 3 cm 3 cm 3 cm 3 cm 3 cm 3s cm 3 cm 3 cm 3 cm 3 cm 3 cm 3s cm 3 cm 3 cm 3 cm 3 cm 3 cm 3s cm 3 cm 3 cm 3 cm 3 cm 3 cm 3s cm 3 cm 3 cm 3 cm 3 cm 3 cm 3s cm 3 cm 3 cm 3 cm 3 cm 3 cm 3s cm 3 cm 3 cm 3 cm 3 cm 3 cm 3s cm 3 cm 3 cm 3 cm 3 cm 3 cm 3s cm 3 cm 3 cm 3 cm 3 cm 3 cm 330
Figure 3-6●●●●●●2 × carbon rods or 2 D cell zinc carbon batteries9 V PP3 cellWireSmall tubBaking sodaGlovesMethodThe activity series of metals.Project 5: Investigating Water ElectrolysisFirst of all, we need two carbon rods <strong>for</strong> ourelectrodes. If you can get a couple of carbon rods,<strong>the</strong>n great, but if not we can salvage some. We arenot going to be using <strong>the</strong> D cell batteries asbatteries, we only want <strong>the</strong>m <strong>for</strong> <strong>the</strong>ir rods inside!Take a hacksaw (make sure you wear gloves <strong>for</strong>Figure 3-7Baking soda adds free ions.Project 5: Investigating Water Electrolysis31
Project 5: Investigating Water ElectrolysisFigure 3-8this bit) and cut <strong>the</strong> metal casing of <strong>the</strong> battery.The carbon rod is in <strong>the</strong> middle of <strong>the</strong> batterysurrounded by electrolyte goo. You need to clean<strong>the</strong> rod, disposing of <strong>the</strong> spent battery casing, and<strong>the</strong> goo, sensibly.Once you have two clean rods, connect <strong>the</strong>m toei<strong>the</strong>r terminal of a 9 V battery using short lengthsof wire. Now immerse <strong>the</strong>m in a solution of waterin a small tub.What happens? . . . Very little! The reason isthat ordinary water is a pretty poor conductor ofelectricity. We need to add some free ions to <strong>the</strong>solution.This comes in <strong>the</strong> <strong>for</strong>m of common baking soda.Add a sprinkle to <strong>the</strong> solution, and see <strong>the</strong> bubbles<strong>for</strong>m!You can capture <strong>the</strong>se bubbles with a test tube,and test <strong>the</strong> respective anode and cathode to see if<strong>the</strong> bubbles are hydrogen or oxygen.ConclusionHydrogen at <strong>the</strong> cathode, oxygen at <strong>the</strong> anode.Free ions are necessary in a solution, <strong>for</strong> electrolysisto take place. In large electrolyzers, we might use astrong alkali-like potassium hydroxide, which ishighly caustic.So what’s happening here?Figure 3-8 gives us a guide as to <strong>the</strong> chemicalreactions that are taking place at <strong>the</strong> anode and <strong>the</strong>cathode. We can see that <strong>the</strong> positively charged ions,<strong>the</strong> cations, move toward <strong>the</strong> cathode, while <strong>the</strong>negatively charged ions, <strong>the</strong> anions, move toward <strong>the</strong>anode. It is <strong>the</strong> power supply to <strong>the</strong> electrolyzer thatprovides <strong>the</strong> energy <strong>for</strong> this movement to take place.We can prove that <strong>the</strong> hydrogen and oxygen arecoming from water by summing <strong>the</strong> chemicalreactions that are taking place at <strong>the</strong> anode and <strong>the</strong>cathode. This is shown in Figure 3-9.Figure 3-9The complete reaction.32
●Project 6: Making <strong>Fuel</strong> from Water with a HoffmanApparatusHoffman apparatusAno<strong>the</strong>r way that we can per<strong>for</strong>m electrolysis iswith a piece of glassware called a Hoffmanapparatus—this contains a reservoir which we fillwith water and something to provide free ions.There are <strong>the</strong>n two electrodes at <strong>the</strong> bottom of twolarge tubes, which have gas taps fitted to <strong>the</strong> top of<strong>the</strong>m.As <strong>the</strong> water is electrolyzed, <strong>the</strong> hydrogen andoxygen accumulate in <strong>the</strong> tubes.Hoffman apparatuses were used in <strong>the</strong> past aselectricity meters when supplies were in D.C. Itwas possible to tell <strong>the</strong> amount of power that hadpassed through <strong>the</strong> Hoffman apparatus by lookingat <strong>the</strong> quantity of gas that had been produced.Producing hydrogen fromrenewablesIf we want a sustainable energy economy, <strong>the</strong>n wecan produce hydrogen from renewable energyusing <strong>the</strong> process of electrolysis.PURE Energy CentreThis is one of <strong>the</strong> things that <strong>the</strong> PURE EnergyCentre in Shetland is hoping to demonstrate.The Shetland Islands have a fantastic windresource, and <strong>the</strong> folks at PURE take this wind,and turn it into hydrogen. They can <strong>the</strong>n storeProject 6: Making <strong>Fuel</strong> from WaterFigure 3-10Hoffman apparatus.Figure 3-11The PURE Energy Centre electrolyzer.33
Project 6: Making <strong>Fuel</strong> from WaterFigure 3-12Two 6-kW proven wind turbines.this as K-type cylinders, and utilize it in anumber of onsite applications, including a fuelcell car, a hydrogen barbecue, and a 5-kW PEMfuel cell.They have a substantial electrolyzer (shown inFigure 3-11)—this takes spare electricity which isnot used <strong>for</strong> <strong>the</strong>—offices from <strong>the</strong> two 6-kWproven wind turbines. As <strong>the</strong> power used togenerate <strong>the</strong> hydrogen is from renewables, noclimate-damaging carbon emissions are producedin <strong>the</strong> process.HARI–The Hydrogen andRenewables IntegrationProjectAno<strong>the</strong>r project, where electrolysis is being used toturn renewable energy into hydrogen, is at HARI,based at West Beacon Farm in Leicestershire, UK.Again, HARI employ an electrolyzer, as seen inFigure 3-13, to turn <strong>the</strong> electricity from <strong>the</strong> portfolioof renewables into hydrogen gas.Figure 3-13 The HARI electrolyzer. Image courtesyDr Rupert Gammon34
Project 6: Making <strong>Fuel</strong> from WaterFigure 3-14System map of <strong>the</strong> Hydrogen and Renewables Integration Project. Image courtesy Dr Rupert Gammon.35
HARI has a diverse array of onsite renewablegenerating options, including wind turbines, solarcells, and micro-hydro power. The spare electricityis <strong>the</strong>n converted into hydrogen, which can be usedin <strong>the</strong> onsite stationary fuel cell, or in a proposedhydrogen vehicle which is currently underdevelopment.Project 6: Making <strong>Fuel</strong> from Water36
Chapter 4Hydrogen StorageWhile <strong>the</strong> technological problems of developing fuelcell technology to a stage where it is commerciallyviable are being solved one by one, <strong>the</strong>re are stilla number of o<strong>the</strong>r obstacles to <strong>the</strong> implementationof a hydrogen economy.In a future hydrogen economy, as well as lookingat methods to use hydrogen, e.g fuel cells, wealso need effective ways to store and transporthydrogen.The thing is that <strong>the</strong> present sources of energythat we use have a high energy density by volumeat room temperature. An enormous amount ofenergy can be stored in a gallon of petrol <strong>for</strong> <strong>the</strong>small size that it takes up. By contrast, <strong>the</strong> samequantity of hydrogen would take up a much largerarea—by its nature, it is a gas!While hydrogen provides very favorable figureswhen considering “energy per weight,” <strong>the</strong> figures<strong>for</strong> “energy per volume” do not compare as favorablyto traditional hydrocarbon fuels.There are some inherent challenges in storinghydrogen, due to <strong>the</strong> fact that as a molecule H 2isvery small. Because of this, it can permeate manymaterials that would at first glance seem suitablematerials <strong>for</strong> construction of hydrogen storagevessels.At atmospheric pressure, <strong>the</strong> size of tank neededto store a quantity of hydrogen, compared to ahydrocarbon fuel with <strong>the</strong> same amount of energy,means that <strong>the</strong> hydrogen tank is many times largerthan <strong>the</strong> conventional hydrocarbon tank, so anyweight saving as a result of using hydrogen ismore than negated.As a result, <strong>the</strong>re is a lot of investigation intostoring hydrogen in so-called “metal hydrides.”The easiest way to think of hydrides is like a“hydrogen sponge” which soaks up hydrogen,but <strong>the</strong>n releases it when heated. Metal hydridestorage cylinders are shown in Figure 4-21(page 48).Project 7: Using Hydrogen Storage Tanks with Desktop<strong>Fuel</strong> <strong>Cell</strong>s●For our hydrogen experiments in this book, we willbe using small lightweight cylinders.An empty storage tank is shown in Figure 4-1, anda full tank in Figure 4-2.37Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
P r o j e c t 8 : B o y l e ’ s L a w a n d C o m p r e s s e d H y d r o g e nFigure 4-1●SyringeEmpty hydrogen storage tank.This is a very, very simple experiment, but it shouldhelp to firmly impress upon you Boyle’s Law.Boyle said that if a fixed quantity of gas is at afixed temperature, its volume will be inverselyproportional to its pressure.Figure 4-2Full hydrogen storage tank.Project 8: Boyle’s Law and Compressed HydrogenStorageIf you take a syringe, fill it with air, and put yourfinger firmly over <strong>the</strong> outlet to prevent any airfrom escaping, you have trapped a fixed quantityof gas inside that syringe. Now, if you depress <strong>the</strong>syringe plunger, you are changing <strong>the</strong> pressureinside <strong>the</strong> syringe. You will notice that as you pushfur<strong>the</strong>r, it becomes harder to press—this is because<strong>the</strong> pressure of your fingers is acting against <strong>the</strong>volume of gas trapped inside <strong>the</strong> syringe. Thevolume has decreased, but <strong>the</strong> pressure hasincreased.38
●●●●●There’s a really natty online simulator, which allowsyou to experiment with Boyle’s Law from <strong>the</strong> com<strong>for</strong>tof your web browser.BalloonFreezer/fridgeBoiling waterBowlMeasuring tapeThe relationship between temperature and <strong>the</strong>volume of a gas is a crucial one <strong>for</strong> us to understandif we are interested in hydrogen storage, as itallows us to do clever things to increase <strong>the</strong> volumeof gas that we can store within a given space.Charles’ Law states: “At constant pressure, <strong>the</strong>volume of a given mass of an ideal gas increasesor decreases by <strong>the</strong> same factor as its temperatureincreases or decreases.”To demonstrate this, take an ordinary balloon andtie it up so that <strong>the</strong> air cannot escape. We now havea fixed volume of gas trapped inside <strong>the</strong> balloon.Wrap <strong>the</strong> measuring tape around <strong>the</strong> balloon andmeasure <strong>the</strong> circumference at <strong>the</strong> widest point. Now,Check out:www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/boyles_law_graph.htmlProject 9: Exploring Charles’ Lawput some boiling water in <strong>the</strong> bowl and immerse <strong>the</strong>balloon to allow <strong>the</strong> boiling water to heat <strong>the</strong>balloon, and thus <strong>the</strong> air inside <strong>the</strong> balloon. Thentake it out of <strong>the</strong> bowl and immediately measure itaround <strong>the</strong> circumference. Then take <strong>the</strong> balloon,and shut it in <strong>the</strong> fridge <strong>for</strong> several minutes. Take itout and measure it again. Then, put <strong>the</strong> balloon in<strong>the</strong> freezer and after several minutes, take it out andmeasure it again.You will see that at higher temperatures, <strong>the</strong>sealed volume of gas inside <strong>the</strong> balloon expands,and <strong>the</strong> balloon increases in size, while, when <strong>the</strong>balloon is chilled, <strong>the</strong> balloon contracts. Cryogenicstorage is one method proposed to store hydrogen<strong>for</strong> use in fuel cell cars. When hydrogen is storedcryogenically, if we can get it to a temperature of20 Kelvin or –253° C, <strong>the</strong> gas changes phase into aliquid. Un<strong>for</strong>tunately, <strong>the</strong>re is a loss of energy incooling <strong>the</strong> hydrogen, which equates to around30% of <strong>the</strong> energy stored.P r o j e c t 9 : E x p l o r i n g C h a r l e s ’ L a w39
P r o j e c t 1 0 : M a k i n g Y o u r O w n “ C a r b o n N a n o t u b e ”Figure 4-3You will see in <strong>the</strong> diagram in Figure 4-3 acryogenic storage tank of <strong>the</strong> kind we might find incars of <strong>the</strong> future powered by hydrogen.By cooling hydrogen, we can make it moredense, and so a fixed volume of gas at roomtemperature will take up a smaller space. This isuseful to us when looking at how to fit lots ofhydrogen into a small vehicle fuel tank!●●●Cryogenic hydrogen storage tank diagram.Online simulation is a good way of finding outabout Charles’ Law. As with Boyle’s Law, <strong>the</strong>re isano<strong>the</strong>r great online simulator at:www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/charles_law.htmlProject 10: Making Your Own “Carbon Nanotube”Drinking straws/paper art strawsPermanent markerLarge round stickersOne of <strong>the</strong> ways in which we can store hydrogenis to adsorb it onto ano<strong>the</strong>r material, as shown inFigure 4-4. Carbon nanotubes are one example of achemical with a high surface area.●Hot melt glue gun (optional)The building block <strong>for</strong> our carbon nanotube is abuckyball. The chemical <strong>for</strong>mula <strong>for</strong> <strong>the</strong> buckyballis C60—this means that if we use two stickers, oneei<strong>the</strong>r side of a straw to <strong>for</strong>m a representation of a40
Figure 4-4 Diagram of hydrogen adsorbed onto a surface. The lighter colored smaller circles represent <strong>the</strong>hydrogen atoms, while <strong>the</strong> larger, darker circles represent <strong>the</strong> carbon atoms.carbon atom, we will need 120 stickers to makeour C60.We represent carbon as being black, so add apermanent marker <strong>for</strong> coloring <strong>the</strong> stickers. Wewill be using straws <strong>for</strong> bonds.Cut your straws into short lengths that are all <strong>the</strong>same. In order to produce a bond, hold <strong>the</strong> strawstoge<strong>the</strong>r in a junction, and <strong>the</strong>n stick a sticker onei<strong>the</strong>r side of <strong>the</strong> join. Start by making a pentagonshape, with five protruding pieces of straw. Thenbegin to turn <strong>the</strong>se additional lengths of straw intohexagons. The completed buckyball will look likeFigure 4-6.Extending our buckyball fur<strong>the</strong>r, we can make acarbon nanotube, which is a long tubular structure,that can be used to adsorb hydrogen.Hydrogen storagein hydridesMetal hydridesMetal hydrides were discovered by accident at <strong>the</strong>Philips Laboratories in Eindhoven, The Ne<strong>the</strong>rlandsin 1969. The researchers found that a specific alloyexposed to hydrogen gas would absorb <strong>the</strong> gas likea chemical sponge. Like squeezing a sponge causesit to release <strong>the</strong> water stored within, hydrides can be“squeezed” by applying a little heat. The storage ofwater is <strong>the</strong>re<strong>for</strong>e a reversible process. Thetechnology of metal hydrides has found widespreadP r o j e c t 1 0 : M a k i n g Y o u r O w n “ C a r b o n N a n o t u b e ”Figure 4-5 The materials you will need to make yourcarbon nanotube. Figure 4-6 The completed buckyball.41
H y d r o g e n S t o r a g e i n H y d r i d e sapplication in energy storage in <strong>the</strong> common“nickel metal hydride” batteries that can be foundin many of today’s mobile phones and portableelectronic devices, but in a hydrogen economycould <strong>the</strong>se substances find o<strong>the</strong>r energy storageapplications—in storing hydrogen? One of <strong>the</strong>advantages of metal hydrides is that <strong>the</strong>y can storea very high density of hydrogen at relatively lowpressures; however, this comes at <strong>the</strong> penalty ofmass. Metal hydrides can be seen in Figures 4-8and 4-9. See how <strong>the</strong> hydrogen (small circles) isabsorbed in <strong>the</strong> gaps between <strong>the</strong> large circleswhich represent <strong>the</strong> metal atoms.Complex hydridesComplex hydrides are more sophisticated than metalhydrides, and incorporate additional chemicals toimprove <strong>the</strong> per<strong>for</strong>mance of <strong>the</strong> hydride.Complex hydrides store hydrogen by “locking itup” chemically with metals and o<strong>the</strong>r substancesadded to improve <strong>the</strong> per<strong>for</strong>mance of <strong>the</strong> hydride.Figure 4-7Hydrogen storage in carbon nanotubes.When hydrogen is required, <strong>the</strong> complex hydridesare heated, releasing <strong>the</strong> hydrogen.While complex hydrides offer <strong>the</strong> benefit ofhaving a low volume, and offer vehicle makers <strong>the</strong>opportunity to re-charge on-board, <strong>the</strong>y have <strong>the</strong>disadvantage that <strong>the</strong>y have a relatively high weightcompared to some o<strong>the</strong>r solutions, require hightemperatures <strong>for</strong> operation, and can suffer fromissues with providing an adequate fuel flow <strong>for</strong>some applications. As a technology, <strong>the</strong>y can stillbe considered to be in “development.” An exampleof <strong>the</strong> structure of a complex hydride can be seenin Figures 4-10 and 4-11. In Figure 4-10 <strong>the</strong> smallcircles represent hydrogen gas, <strong>the</strong> large darkcircles represent metal atoms, and <strong>the</strong> light coloreddark circles represent additive atoms included toimprove <strong>the</strong> per<strong>for</strong>mance of <strong>the</strong> complex hydride.Chemical hydridesChemical hydrides store hydrogen in <strong>the</strong>irchemical structure—releasing it when exposed to a42
Figure 4-82D representation of metal hydride.H y d r o g e n S t o r a g e i n H y d r i d e sFigure 4-93D representation of metal hydride.Figure 4-102D representation of complex hydride.43
Figure 4-122D representation of chemical hydride.Figure 4-113D representation of complex hydride.H y d r o g e n S t o r a g e i n H y d r i d e scatalyst, we are going to experiment with chemicalhydrides later in this book using <strong>the</strong> H-Gen reactor.Chemical hydrides can be ei<strong>the</strong>r liquids or solids.They have <strong>the</strong> potential to offer a low weight andvolume solution—<strong>the</strong> fact that chemical hydridescan be distributed in liquid <strong>for</strong>m opens up <strong>the</strong>opportunity of using <strong>the</strong> existing infrastructure todistribute <strong>the</strong> hydrides. The disadvantage of usingchemical hydrides is that <strong>the</strong> spent hydride wouldneed to be stored on board <strong>the</strong> vehicle, andexchanged <strong>for</strong> fresh reprocessed hydride.Reprocessing hydrides requires infrastructure,technology, and equipment. Figure 4-12 is arepresentation of a chemical hydride. See howo<strong>the</strong>r chemicals act as a “carrier” <strong>for</strong> <strong>the</strong> hydrogen.There are such a wide range of hydride storagecompounds—<strong>the</strong> array is bewildering! Looking atFigure 4-13 gives you <strong>the</strong> chemical <strong>for</strong>mulas <strong>for</strong>some hydrides that have been discovered, plotting<strong>the</strong>ir volumetric density and density by mass.There is also a comparison to some o<strong>the</strong>r hydrogenstorage methods.For hydrogen to become of practical use inautomotive applications, we need to improve ourability to store it. We can see how currentapproaches to storing hydrogen compare to <strong>the</strong>energy density of a tank of gasoline in Figure 4-14.We can also see <strong>the</strong> Department of Energy’s goal<strong>for</strong> hydrogen storage, which gives us a realisticidea of how much <strong>the</strong> technology is likely toimprove.While we probably will not be able to comeclose to <strong>the</strong> energy density of gasoline, this is notnecessarily a problem, as we can circumventissues of energy storage by designing vehiclesto be lighter, more aerodynamic, and more fuelefficient,so that <strong>the</strong>y use less energy in <strong>the</strong>first place.44
Figure 4-13A range of hydrides and <strong>the</strong>ir storage capacities.H y d r o g e n S t o r a g e i n H y d r i d e sFigure 4-14Hydrogen storage roadmap.45
P r o j e c t 1 1 : G e n e r a t i n g H y d r o g e n U s i n g t h e H - G e n●●H-GenSodium borohydrideA small container of sodium borohydride, likethat shown in Figure 4-15, will be more thansufficient to produce much hydrogen from <strong>the</strong>H-Gen <strong>for</strong> experimentation.We see, looking at <strong>the</strong> chemical structure ofsodium borohydride in Figure 4-16, that <strong>for</strong> everysodium and boron atom, <strong>the</strong>re are four atoms ofhydrogen.MethodProject 11: Generating Hydrogen Using <strong>the</strong> H-GenTake <strong>the</strong> H-Gen hydrogen generator, and half fill itwith water; it will only take about 15 ml. You don’tFigure 4-15A container of sodium borohydride.Figure 4-16borohydride.The chemical structure of sodiumneed anything special—ordinary tap water will do<strong>for</strong> this one.Add about a tenth of a gram of sodiumborohydride. You can use a spatula, <strong>for</strong> example,<strong>the</strong> item in Figure 4-17. At this point, you won’tsee a thing. Now drop <strong>the</strong> catalyst into <strong>the</strong> water.Immediately, you should see small bubbles.The end product of this reaction is sodiumborate: NaBO 2. We generate such small quantitiesthat <strong>the</strong>re is not a problem getting rid of it down<strong>the</strong> sink.Figure 4-17 Spatula used to measure <strong>the</strong> quantity ofsodium borohydride.46
Figure 4-18 Diagram showing <strong>the</strong> H-Gen producinghydrogen gas.ConclusionThis simple experiment shows us that <strong>the</strong>re areo<strong>the</strong>r ways of generating useful quantities ofhydrogen besides using <strong>the</strong> electrolysis of water.The next question might be “so why don’t we justuse loads of sodium borohydrate to solve ourenergy crisis?” Well, we could, as certainlyresearch is being done into vehicles using chemicalhydrides to power <strong>the</strong>m (see Figure 13-39 <strong>for</strong> moreabout how this would work). However, chemicalhydride powered vehicles would require a differentinfrastructure again <strong>for</strong> refueling—as equipmentwould be needed to “recharge” <strong>the</strong> chemical●●●●H-GenTimerKettleIce cubesFigure 4-19 Hydrogen produced by <strong>the</strong> H-Genpowering a mini PEM fuel cell.hydrides with hydrogen gas. While chemicalhydrides have <strong>the</strong> advantage of being lightweightand low-volume, <strong>the</strong> materials need to be removedfrom <strong>the</strong> vehicle <strong>for</strong> regeneration, and <strong>the</strong>associated technologies and infrastructure couldprove expensive.When cleaning <strong>the</strong> H-Gen, be very sure not tolose <strong>the</strong> reactors. It is <strong>the</strong>se reactors that make up<strong>the</strong> bulk of <strong>the</strong> cost of <strong>the</strong> H-Gen unit. If <strong>the</strong>ybreak, do not discard <strong>the</strong>m, as <strong>the</strong>y will still work.Project 12: Changing <strong>the</strong> H-Gen Rate of ReactionIntroductionThe H-Gen produces enough hydrogen to powermost fuel cells that produce up to 1.5 W of power.For some, slightly larger, fuel cells, we might needmore hydrogen, or we might want to producehydrogen at a higher rate.P r o j e c t 1 2 : C h a n g i n g t h e H - G e n R a t e o f R e a c t i o n47
P r o j e c t 1 2 : C h a n g i n g t h e H - G e n R a t e o f R e a c t i o nIn this experiment, we are going to look at <strong>the</strong>factors that affect <strong>the</strong> rate of hydrogen productionin <strong>the</strong> H-Gen unit.In order to do this experiment, we will need ameans of regulating <strong>the</strong> temperature of our water.A kettle and ice cubes provide a sound way ofmaking varying temperatures of water between0° C (32° F) and 100° C (212° F).Metal hydridesUsing <strong>the</strong> apparatus shown in Figure 4-20, we canexperiment with hydrides, changing <strong>the</strong> temperatureof <strong>the</strong> cylinders on each side, causing <strong>the</strong> pressureon each side to change. The valve in <strong>the</strong> middlecan be opened or closed to allow <strong>the</strong> pressure toequalize, or build up in one side.Figures 4-21 and 4-22 are examples of <strong>the</strong>types of hydride cylinder you could use to storeFigure 4-20hydrides.Apparatus <strong>for</strong> experimenting with metalFigure 4-21hydrogen in <strong>for</strong> experimentation and work withsmall-scale fuel cells.Metal hydrides are one option <strong>for</strong> storinghydrogen <strong>for</strong> transport applications; however, <strong>the</strong>technology will need to develop fur<strong>the</strong>r if it is toprovide <strong>the</strong> range that consumers want.At <strong>the</strong> PURE Energy Centre, <strong>the</strong>y have developedan electric car with hydrogen hybrid drive. A hydridecylinder is used to store hydrogen <strong>for</strong> <strong>the</strong> vehicle,and it is recharged from a supply stored incompressed hydrogen tanks, which we will lookat next.Figure 4-22Example 1 of metal hydride cylinders.Example 2 of metal hydride cylinder.48
Figure 4-23 PURE Energy Centre fuel cell car fittedwith metal hydride hydrogen storage.Compressed hydrogen storageOne of <strong>the</strong> simplest ways to store hydrogen is tokeep it as pressurized gas. Un<strong>for</strong>tunately, thisdoes have <strong>the</strong> disadvantage that <strong>the</strong> gas occupies alarge volume; however, it is a relatively simpleapproach.Un<strong>for</strong>tunately, compressing gas requires someenergy, so as fuel cell scientists, we need to beaware that <strong>the</strong> “work” required to compress ourhydrogen is going to require some additionalenergy input, which may affect <strong>the</strong> economics ofrunning our system.The PURE and HARI projects both usecompressed hydrogen storage, in order to store <strong>the</strong>hydrogen <strong>the</strong>y produce from spare renewableenergy.At <strong>the</strong> PURE Centre, <strong>the</strong> electrolyzer works at arelatively high pressure, from which it enters <strong>the</strong>hydrogen storage cylinders.Figure 4-24 Compressed hydrogen storage at <strong>the</strong>PURE Energy Centre.Figure 4-25 Hydrogen compressor at HARI project,West Beacon Farm. Image courtesy Dr Rupert Gammon.P r o j e c t 1 2 : C h a n g i n g t h e H - G e n R a t e o f R e a c t i o n49
P r o j e c t 1 2 : C h a n g i n g t h e H - G e n R a t e o f R e a c t i o nFigure 4-26Hydrogen storage at <strong>the</strong> HARI project, West Beacon Farm. Image courtesy Dr Rupert Gammon.At <strong>the</strong> HARI project, a slightly differentapproach is used, whereby <strong>the</strong> hydrogen is firstcompressed, using <strong>the</strong> hydrogen compressor shownin Figure 4-25 and <strong>the</strong>n stored in <strong>the</strong> hydrogencylinders shown in Figure 4-26.By storing hydrogen in this way, <strong>the</strong> supply ofenergy can be matched with demand, and spareenergy can be used to produce transport fuel.50
Chapter 5Platinum <strong>Fuel</strong> <strong>Cell</strong>sIntroductionWe saw that Grove’s original fuel cells employedplatinum electrodes. You can recreate Grove’soriginal gas battery by using a couple of lengths ofplatinum wire.We are going to omit <strong>the</strong> dangerous sulfuric acidused in Grove’s original experiments, replacing itinstead with a mixture of water and commontable salt.From this simple experiment, you will learn <strong>the</strong>basics of fuel cell technology, which will act as aspringboard to allow you to progress onto biggerand better technologies.Project 13: Build Your Own Platinum <strong>Fuel</strong> <strong>Cell</strong>MethodMaking <strong>the</strong> platinum fuel cell●●●●●●A small tumbler full of distilled water and a pinchof saltVoltmeterBatteryConnection leadsLength of platinum wireBatteryAn old film canister makes a perfect littlecontainer <strong>for</strong> our platinum fuel cell.Fill a tumbler with water, and put <strong>the</strong> tiniestsprinkle of salt in it. Common household salt, suchas shown in Figure 5-1, is ideal.In order to construct <strong>the</strong> fuel cell, you will needto cut <strong>the</strong> platinum wire in half, and wrap it arounda thin cylindrical object, such as <strong>the</strong> probe of amultimeter or a biro refill. This gives us a spiralthat we can immerse in <strong>the</strong> water, and gives us alarge surface area exposed to <strong>the</strong> water.Two tightly wound coils of wire, such as thoseshown in Figure 5-2, should result.Now, put <strong>the</strong> two coils of wire at opposite sidesof <strong>the</strong> glass, and using <strong>the</strong> crocodile clips on yourconnection leads, clip <strong>the</strong> wire to <strong>the</strong> side of <strong>the</strong>glass, immersing it in <strong>the</strong> water. See Figure 5-3.The crocodile clips must provide good electricalcontact between <strong>the</strong> platinum wire and <strong>the</strong> clip51Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
Project 13: Build Your Own Platinum <strong>Fuel</strong> <strong>Cell</strong>Figure 5-1Figure 5-2Common table salt.Two small coils of platinum wire.Figure 5-3beaker.Wires positioned on ei<strong>the</strong>r side of <strong>the</strong>itself, as well as supporting <strong>the</strong> wire and holding itin place (Figure 5-4).The wire should be covered by <strong>the</strong> salt water,but <strong>the</strong> water should not touch <strong>the</strong> crocodile clips.The crocodile clips are made from metal thatis “reactive” and so could <strong>for</strong>m a galvanic cell(a battery), whereas <strong>the</strong> platinum will not react, andso any power being produced is as a result of <strong>the</strong>hydrogen and oxygen, not <strong>the</strong> reaction of <strong>the</strong> metals.Figure 5-4 Close-up of <strong>the</strong> wires clipped snugly to<strong>the</strong> inside of <strong>the</strong> container.52
Making a fair testWe want to check that <strong>the</strong> voltage that we are producingfrom our platinum fuel cell really is as aresult of <strong>the</strong> hydrogen and oxygen produced, not asa result of any galvanic circuit. There<strong>for</strong>e, we mustmeasure <strong>the</strong> voltage between <strong>the</strong> platinum electrodesimmersed in <strong>the</strong> salt water solution.Now, using <strong>the</strong> most sensitive DC voltage settingof your voltmeter, measure <strong>the</strong> potential across <strong>the</strong>two electrodes.It should register zero.Generating a little hydrogen(and oxygen)We are now going to charge our platinum fuel cell,connecting <strong>the</strong> wires to a battery will cause gas tobe evolved at <strong>the</strong> two electrodes. Connect three of<strong>the</strong> 2 V lead acid batteries in series. We read aboutthis reaction—electrolysis—in Chapter 3.A schematic diagram of <strong>the</strong> setup can be seen inFigure 5-5, and a picture of <strong>the</strong> completed setupcan be seen in Figure 5-6.Now, take a voltmeter and connect it across <strong>the</strong>two electrodes, as shown in Figure 5-7.Figure 5-6electrolysis.A picture of <strong>the</strong> completed setup <strong>for</strong>As can been seen in Figure 5-8, a voltage willregister on your meter. Your meter should be set toone of <strong>the</strong> most sensitive DC voltage settings.Observe <strong>the</strong> two electrodes during and afterelectrolysis, and during <strong>the</strong> process of voltage beinggenerated. What do you notice about <strong>the</strong> amount ofbubbles being <strong>for</strong>med at <strong>the</strong> two electrodes? Are<strong>the</strong>re more at one than at <strong>the</strong> o<strong>the</strong>r? Take a look atProject 13: Build Your Own Platinum <strong>Fuel</strong> <strong>Cell</strong>Figure 5-5oxygen.Schematic <strong>for</strong> generating hydrogen andFigure 5-7 Schematic of voltmeter connected across<strong>the</strong> platinum electrodes.53
Project 13: Build Your Own Platinum <strong>Fuel</strong> <strong>Cell</strong>Figure 5-8The platinum fuel cell generating electricity.Figures 5-9 and 5-10, which are a close-up viewof <strong>the</strong> two electrodes that were taken duringelectrolysis.As we saw in <strong>the</strong> experiments on electrolysis,<strong>the</strong> positively charged ions—which we call <strong>the</strong>cations—go to <strong>the</strong> cathode, whereas <strong>the</strong> negativelycharged ions, <strong>the</strong> anions, migrate toward <strong>the</strong> anode.When <strong>the</strong>y reach <strong>the</strong> anode and cathode, <strong>the</strong>y “giveup” <strong>the</strong>ir charge to <strong>the</strong> electrode, completing <strong>the</strong>circuit.Once we have <strong>for</strong>med a small amount of gas,this gas sticks to <strong>the</strong> electrode, a very primitive<strong>for</strong>m of storage—certainly not enough storage todo anything useful on a large scale.Once we have produced hydrogen and oxygenon <strong>the</strong> electrodes of <strong>the</strong> fuel cell, we can <strong>the</strong>n“release” this imbalance of charge by creating acircuit with <strong>the</strong> voltmeter.Then <strong>the</strong> platinum acts as a catalyst. Its catalyticaction allows <strong>the</strong> hydrogen ions to break up intoelectrons, which flow through <strong>the</strong> electrode and <strong>the</strong>Figure 5-9aClose-up of <strong>the</strong> <strong>the</strong> oxygen electrode.54
Figure 5-9bClose-up of <strong>the</strong> hydrogen electrode.circuit. At <strong>the</strong> anode, <strong>the</strong> oxygen bubbles whichcling to <strong>the</strong> electrode receive electrons from <strong>the</strong>electrode, and combine with <strong>the</strong> hydrogen ions thatare in <strong>the</strong> water to produce water.This process is illustrated in Figure 5-10.Figure 5-10 Platinum fuel cell electrochemistry.Hydrogen is produced at <strong>the</strong> cathode and oxygenat <strong>the</strong> anode.Proving that <strong>the</strong> catalyticeffect of platinumis requiredPlatinum is unique because of its catalytic properties.This is why <strong>the</strong>y use it in car “catalytic converters,”as well as in many industrial applications.Un<strong>for</strong>tunately, it is also very expensive. If only wecould use something o<strong>the</strong>r than platinum . . . Well,tough! At <strong>the</strong> moment, we can’t! Try using twoo<strong>the</strong>r wires of <strong>the</strong> same metal and, while you willsee electrolysis take place, you will not see anysignificant voltage when connecting <strong>the</strong> meter.If you want to take platinum fuel cells fur<strong>the</strong>r:There are some online movies at:www.geocities.com/fuelcellkit/pics/FCK1.mpgwww.geocities.com/fuelcellkit/pics/FCK2.mpgwww.geocities.com/fuelcellkit/pics/FCK3.mpgHere is ano<strong>the</strong>r nice site to check out <strong>for</strong> platinumfuel cells:www.scitoys.com/scitoys/scitoys/echem/fuel_cell/fuel_cell.htmlTaking it fur<strong>the</strong>rTake a look at Grove’s original gas battery inFigure 5-11. Grove used multiple cells in hisbattery to produce higher voltage. How could youmake a platinum fuel cell with multiple cells? As ahint, you can obtain safety test tubes, often inchemistry kits <strong>for</strong> a younger audience. These canProject 13: Build Your Own Platinum <strong>Fuel</strong> <strong>Cell</strong>55
Project 13: Build Your Own Platinum <strong>Fuel</strong> <strong>Cell</strong>Figure 5-11Grove’s gas battery.be drilled safely, unlike glass, allowing youto experiment and make multiple cells. Later inthis book, we are going to look at fuel cell“stacks.” Keep this in mind, and think back toGrove’s gas battery when you encounter thisin<strong>for</strong>mation.56
Chapter 6Alkaline <strong>Fuel</strong> <strong>Cell</strong>sWe saw in Chapter 1 how alkaline fuel cells playedan important role in <strong>the</strong> early development of fuelcells, having been developed by Francis Bacon atCambridge University. In fact, because of <strong>the</strong>irinventor, you may hear <strong>the</strong>m referred to as “Baconcells.” As you will know from reading this chapter,alkaline fuel cells, such as those shown in Figure 6-1,were used in early space missions, and are a verywell-developed fuel-cell technology.One of <strong>the</strong> advantages of a fuel cell in space isthat you already have <strong>the</strong> hydrogen and oxygen,and <strong>the</strong> water is pretty useful <strong>for</strong> astronauts todrink too!The chemistry of an alkaline fuel cell differsslightly from some of <strong>the</strong> o<strong>the</strong>r fuel cells in thisbook. In a PEM fuel cell, it is <strong>the</strong> protons whichare exchanged through <strong>the</strong> membrane, while <strong>the</strong>electrons complete <strong>the</strong> circuit. In an alkaline fuelcell, it is “hydroxy ions” that make <strong>the</strong> journeyfrom electrode to electrode, and <strong>the</strong> water, whichis a product of <strong>the</strong> combination of hydrogen andoxygen, is produced at <strong>the</strong> anode, ra<strong>the</strong>r thanFigure 6-2<strong>the</strong> cathode—which means that <strong>the</strong> water isproduced on <strong>the</strong> “hydrogen side” ra<strong>the</strong>r than <strong>the</strong>“oxygen side.”If we look at <strong>the</strong> pairs of chemical reactionswhich are taking place at each electrode (seeFigure 6-2), we see that:At <strong>the</strong> anodeThe chemistry of alkaline fuel cells.Hydrogen is oxidized, producing electrons in <strong>the</strong>process.At <strong>the</strong> cathodeFigure 6-1 An early AFC used in <strong>the</strong> space program.Image courtesy NASA.Oxygen is reduced, producing “hydroxide ions,”which migrate across <strong>the</strong> electrolyte of <strong>the</strong> alkalinefuel cell.So reduction and oxidization are happeningat <strong>the</strong> same time . . . Remember LEO <strong>the</strong> Liongoing GER?If you want to look at this in terms of a diagram,Figure 6-4 shows <strong>the</strong> layout of an alkaline fuelcell. Here we can see how <strong>the</strong> “exhaust” from <strong>the</strong>57Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
Figure 6-3Reduction and oxidization (remember LEO <strong>the</strong> Lion?).Alkaline <strong>Fuel</strong> <strong>Cell</strong>sFigure 6-4Figure 6-5Diagrammatic representation of an alkaline fuel cell.The chemical reactions taking place inside an alkaline fuel cell.58
fuel cell comes from <strong>the</strong> anode side of <strong>the</strong> fuelcell, ra<strong>the</strong>r than <strong>the</strong> cathode.If we now superimpose <strong>the</strong> chemical reactionsthat are taking place onto this diagram, we getFigure 6-5.We can see that <strong>the</strong> hydrogen enters to <strong>the</strong> topright, <strong>the</strong> oxygen to <strong>the</strong> top left, and we can seehow electrons are flowing from <strong>the</strong> anode, to <strong>the</strong>cathode, via <strong>the</strong> circuit. Looking at <strong>the</strong> cathode, wecan see how electrons and oxygen <strong>for</strong>m hydroxylions, which flow across <strong>the</strong> electrolyte of <strong>the</strong>alkaline fuel cell, and recombine with <strong>the</strong> hydrogenprotons to make H 2O, or water, which is <strong>the</strong> outputfrom <strong>the</strong> fuel cell.Project 14: Making Electricity with Alkaline <strong>Fuel</strong> <strong>Cell</strong>sNow, we are going to get to grips with using a realalkaline fuel cell. To begin with, we are just goingto check that we can produce some power from ourfuel cell, and as <strong>the</strong> chapter goes on, we are goingto per<strong>for</strong>m some simple experiments which willenable us to learn more about <strong>the</strong> per<strong>for</strong>mance ofalkaline fuel cells.●Alkaline mini fuel cell (<strong>Fuel</strong> <strong>Cell</strong> Store P/N:530709)● Potassium hydroxide (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 500200)● Sodium borohydride (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 560109)● Multimeter (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 596007)●●●Small scoopAccurate scales1 liter graduated jugThe assembled fuel cell, as delivered, shouldlook something like Figure 6-6. You will noticethat <strong>the</strong> sockets, and cutouts in <strong>the</strong> plastic on <strong>the</strong>top of <strong>the</strong> fuel cell, ensure that <strong>the</strong> two componentscan only seat properly when <strong>the</strong>y are correctlylined up.The anode of <strong>the</strong> mini alkaline fuel cell is <strong>the</strong>clear outer tub, shown in Figure 6-7.If you look inside <strong>the</strong> tub, you will see a squareaffixed to <strong>the</strong> bottom of <strong>the</strong> tub—this is <strong>the</strong> anodeelectrode, shown in Figure 6-8, and it connects to<strong>the</strong> anode terminal, which employs a 4-mm bananaplug, also shown in Figure 6-8.The red plastic piece which came supplied with<strong>the</strong> tub is shown in Figure 6-9. This is <strong>the</strong> minifuel cell cathode assembly.You will notice that <strong>the</strong>re is a similar piece ofmaterial on <strong>the</strong> bottom of <strong>the</strong> red molding—this is<strong>the</strong> cathode electrode, as indicated in Figure 6-10.The cathode comes with a similar 4-mm bananasocket, as shown also in Figure 6-10.You can see a cross-sectional view of <strong>the</strong> fuelcell in Figure 6-11. Notice that <strong>the</strong> two electrodesare opposite each o<strong>the</strong>r.Thinking about <strong>the</strong> diagram shown earlier inFigure 6-5, it should become easy to relate <strong>the</strong>components of <strong>the</strong> mini alkaline fuel cell to <strong>the</strong>diagram. We can envisage <strong>the</strong> oxygen being drawnfrom <strong>the</strong> center of <strong>the</strong> fuel cell. However, you willnotice that <strong>the</strong>re is no “hydrogen input tube.” Thisfuel cell gets its hydrogen fuel from chemicalsdissolved in <strong>the</strong> electrolyte solution.You will remember Chapter 4, where we usedsodium borohydride. Well, we are going to use itProject 14: Electricity with Alkaline <strong>Fuel</strong> <strong>Cell</strong>s59
Project 14: Electricity with Alkaline <strong>Fuel</strong> <strong>Cell</strong>sFigure 6-6Figure 6-7The assembled mini alkaline fuel cell.The mini alkaline fuel cell anode.Figure 6-8 Note <strong>the</strong> location of <strong>the</strong> anode electrodeand terminal.60
Figure 6-9assembly.The mini alkaline fuel cell cathodeagain as <strong>the</strong> source of fuel <strong>for</strong> our alkaline fuelcell.You will need a small bottle of sodium borohydride,like that in Figure 6-12.Later in this chapter, we are going to experimentwith some different “hydrogen carriers,” but <strong>for</strong><strong>the</strong> moment, let’s go with what works well! Youwill also need a small scoop <strong>for</strong> <strong>the</strong> sodiumborohydride.Figure 6-10 Note <strong>the</strong> location of <strong>the</strong> cathodeelectrode and terminal.Figure 6-11fuel cell.Cross-sectional view of <strong>the</strong> mini alkalineIf you are going to order sodium borohydridethrough <strong>the</strong> post, many countries and states willrequire that you specify “hazardous materialspostage,” which costs a little extra—be mindful ofthis when thinking about how much to order!Figure 6-12 Sodium borohydride, <strong>the</strong> source ofhydrogen <strong>for</strong> our AFC.Project 14: Electricity with Alkaline <strong>Fuel</strong> <strong>Cell</strong>s61
Project 14: Electricity with Alkaline <strong>Fuel</strong> <strong>Cell</strong>sFigure 6-13 Very small scoop, suitable <strong>for</strong> measuringsodium borohydride.Now, remember this is an “alkaline fuel cell,”but “Where is <strong>the</strong> alkaline?” I hear you shout—well,it comes in <strong>the</strong> <strong>for</strong>m of potassium hydroxide.Figure 6-14 shows a bag of potassium hydroxide.If you can’t get any of this stuff, <strong>the</strong>n have a playaround with some alternative alkalis, as shown in<strong>the</strong> later experiments—per<strong>for</strong>mance might be a bitimpaired, but it will prove <strong>the</strong> principle.Now, we need to prepare a 1 M solution of this.To do this, we need 56 grams of potassiumhydroxide in a measuring jug—56.10564 g/mol—to which we will add water to make 1 liter.Figure 6-14Potassium hydroxide.Figure 6-15Do not fill past this line!We need to take about 65 cm 3 of this to fill ourfuel cell.If you’ve got 65 cm 3 of <strong>the</strong> alkaline electrolytesolution, <strong>the</strong>n it should all work out just fine—butwhatever you do, do not fill past <strong>the</strong> line shown inFigure 6-15. You may need to top up a little bit toreach <strong>the</strong> line—this is fine, but do not go above it.Don’t be alarmed, don’t be scared! If <strong>the</strong> liquidstarts looking a bit black <strong>the</strong> first time you use <strong>the</strong>fuel cell, it is only a little bit of <strong>the</strong> carboncoming out of <strong>the</strong> cloth electrodes—don’t panic,as this is normal.62
Figure 6-16voltmeter.Add a pinch of <strong>the</strong> sodium borohydride, using<strong>the</strong> small measuring scoop. You don’t need verymuch at all.●The alkaline fuel cell connected to <strong>the</strong>Figure 6-17voltmeter.Schematic <strong>for</strong> connecting <strong>the</strong> AFC to <strong>the</strong>Now, simply and straight<strong>for</strong>wardly, we are goingto put <strong>the</strong> cathode into <strong>the</strong> anode pot, and connect<strong>the</strong> fuel cell to a voltmeter. The setup will look likeFigure 6-16, and <strong>the</strong> schematic is as simple asFigure 6-17.There really is nothing to it!Your alkaline fuel cell should be producingpower, so set your meter to its most sensitive D.C.voltage setting and look at <strong>the</strong> reading!Project 15: Plotting <strong>the</strong> IV Characteristics of an AFCAlkaline mini fuel cell (<strong>Fuel</strong> <strong>Cell</strong> Store P/N:530709)● Potassium hydroxide (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 500200)● Sodium borohydride (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 560109)● 2 × multimeter (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 596007)●Variable resistance●●●Small scoopAccurate scales1 liter graduated jugIn this experiment, we will be setting up <strong>the</strong>alkaline fuel cell exactly as we did in <strong>the</strong> lastexperiment; however, <strong>the</strong> step that will differ isProject 15: Plotting <strong>the</strong> IV Characteristics of an AFC63
Project 15: Plotting <strong>the</strong> IV Characteristics of an AFChow we set up <strong>the</strong> multimeters to monitor <strong>the</strong> fuelcell’s per<strong>for</strong>mance. We will be connecting <strong>the</strong> fuelcell to a variable load—a variable resistor, andmeasuring <strong>the</strong> voltage across <strong>the</strong> fuel cell, and <strong>the</strong>current flowing through <strong>the</strong> load. Each time wechange <strong>the</strong> variable resistance, we need to disconnect<strong>the</strong> resistor, and quickly take a reading of <strong>the</strong>resistance of <strong>the</strong> resistor, write it down! Don’t tryand remember—it never works. Then, quicklyconnect it back in <strong>the</strong> circuit, read <strong>the</strong> current andvoltage, and write <strong>the</strong>m down too!In fact, I’m so adamant that writing it down is agood idea that I have even provided you with anatty little table to write <strong>the</strong>m in (Table 6-1)!We are going to be plotting a current-voltagecurve <strong>for</strong> our alkaline fuel cell. To do this, we firstneed to obtain a series of values. So, you’re goingto have to connect everything up as shown inFigure 6-18. A schematic is shown in Figure 6-19.Now, you have two options. The simple way isto use a pen and paper. I’ve provided you with ablank graph, so you can give it a go with plottingyour points. This is Figure 6-20.Table 6-1Record resistance, current and voltage <strong>for</strong> youralkaline fuel cell.Resistance (R) Voltage (V) Current (I) Ohms V Volts A Amps V A V A V A V A V A V A V A V A V AFigure 6-18setup.The alkaline fuel cell measurementYou will notice that <strong>the</strong> voltage is across <strong>the</strong>x-axis of <strong>the</strong> graph. There is a lesson here—myscience teacher, Mr Kaufman, used to patrol <strong>the</strong>room, carefully scrutinizing everyone’s neatlyplotted graphs. There was deadly silence.Suddenly, <strong>the</strong> silence would be broken:“Control your bottom, young man,” he’d shout atsome un<strong>for</strong>tunate pupil. It was nothing to dowith what <strong>the</strong> student had eaten <strong>for</strong> breakfast—itwas more to do with <strong>the</strong> graphs! We alwaysput <strong>the</strong> thing that we can control at <strong>the</strong> bottomof <strong>the</strong> graph. In this case, we are plottingvoltage and current, but we are “controlling” <strong>the</strong>voltage, by using <strong>the</strong> variable resistor. So, whenplotting graphs, remember to “control yourbottom.”64
Figure 6-19 Schematic diagram <strong>for</strong> <strong>the</strong> alkaline fuel cell measurement setup.Figure 6-20 Blank graph <strong>for</strong> plotting IV characteristic Figure 6-21 Completed graph plotting IVof <strong>the</strong> alkaline fuel cell.characteristic of <strong>the</strong> alkaline fuel cell.Project 15: Plotting <strong>the</strong> IV Characteristics of an AFC65
Project 16: Plotting <strong>the</strong> Power Curve of an AFCProject 16: Plotting <strong>the</strong> Power Curve of an AFC●Alkaline mini fuel cell (<strong>Fuel</strong> <strong>Cell</strong> Store P/N:530709)● Potassium hydroxide (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 500200)● Sodium borohydride (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 560109)● 2 × multimeter (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 596007)●●●●Variable resistanceSmall scoopAccurate scales1 liter graduated jugGreat news! We are going to take <strong>the</strong> data from<strong>the</strong> last experiment, and process it in a differentway to learn something else about <strong>the</strong> characteristicsof <strong>the</strong> alkaline fuel cell.If you haven’t carried out <strong>the</strong> previous experiment,I’d suggest you do so now, as we are going to need<strong>the</strong> data.Transfer <strong>the</strong> data about voltage and current toTable 6-2.Once you have taken your readings and writtendown your series of values, you can compute <strong>the</strong>power column in <strong>the</strong> table. This is really simple.To find D.C. power, you simply take <strong>the</strong> voltage(in volts), and multiply it by <strong>the</strong> current (in amps),which gives you watts.Table 6-2Voltage, current and power <strong>for</strong> an alkaline fuel cellVoltage (V) Current (I) Power (P)V Volts A Amps W WattsV A WV A WV A WV A WV A WV A WWe are now going to plot <strong>the</strong> power curve of ourAFC. You’re provided with a blank set of axes inFigure 6-22 (although bear in mind that as powerchanges dramatically as a result of alkaline andfuel, you may need to redraw different axes withdifferent scales.) An example of how your powercurve might look is shown in Figure 6-23.Figure 6-22Blank power curve graph.66
Figure 6-23●Alkaline mini fuel cell (<strong>Fuel</strong> <strong>Cell</strong> Store P/N:530709)● Potassium hydroxide (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 500200)●Sodium hydroxide (drain cleaner)● Sodium borohydride (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 560109)● Multimeter (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 596007)●Variable resistorExample power curve graph.Project 17: Comparing <strong>the</strong> Per<strong>for</strong>mance of DifferentAlkaline ElectrolytesIn this experiment, we are going to compare <strong>the</strong>per<strong>for</strong>mance of <strong>the</strong> alkaline fuel cell using twodifferent alkaline solutions—potassium hydroxide(which we have been using in <strong>the</strong> o<strong>the</strong>r experiments),and sodium hydroxide, which is also known asdrain cleaner. In order to make a fair experiment,we are going to use sodium borohydride as <strong>the</strong> fuel<strong>for</strong> both experiments. For <strong>the</strong> first experiment, use<strong>the</strong> sodium hydroxide as <strong>the</strong> alkali. Prepare a 1 Msolution—you will need to add 40 g of sodiumhydroxide to a beaker, to which you add a liter ofwater. Use about 65 ml of this to top <strong>the</strong> fuel cellup to <strong>the</strong> fill line. Set <strong>the</strong> experiment up using <strong>the</strong>diagram in Figure 6-19. Set <strong>the</strong> resistor to a valuewhere it registers a flow of current. Wait <strong>for</strong> <strong>the</strong>current to stabilize. Note <strong>the</strong> voltage and currentproduced. Now, repeat <strong>the</strong> experiment with a 1Msolution of potassium hydroxide.You can use Table 6-3 to note your results.Table 6-3Comparison of AFC alkaline solutions.NAOHKOHVoltage (V)Current (A)Project 17: Different Alkaline Electrolytes67
Project 18: Comparing <strong>the</strong> Per<strong>for</strong>mance of Different“Hydrogen Carriers”Project 18: Different “Hydrogen Carriers”●Alkaline mini fuel cell (<strong>Fuel</strong> <strong>Cell</strong> StoreP/N: 530709)● Potassium hydroxide (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 500200)● Sodium borohydride (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 560109)●●●MethanolEthanolA well-stocked drinks cabinet● Multimeter (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 596007)In this experiment, we are going to compare <strong>the</strong>per<strong>for</strong>mance of different liquids that we can use ashydrogen carriers in our alkaline fuel cell. We aregoing to use <strong>the</strong> same potassium hydroxide 1 Msolution in both of our experiments. However,we are going to run one experiment using <strong>the</strong>sodium borohydride (if you did <strong>the</strong> last couple ofexperiments, you could use <strong>the</strong> same results). Then●we are going to thoroughly clean out our fuel cell,and use a methanol solution instead; <strong>the</strong> o<strong>the</strong>rsolution that I recommend testing is ethanol, tocompare <strong>the</strong> per<strong>for</strong>mance with methanol. Then youcan try and think of some o<strong>the</strong>r likely hydrogencarriers, a good suggestion being to crack open <strong>the</strong>drinks cabinet—no, not <strong>for</strong> reckless personalconsumption, but to power our fuel cell. Drinkswith a high alcohol content will produce power inour fuel cell.Table 6-4Comparison of different hydrogen carriers.CH 4OCH 6ONaBH 4Voltage (V)Current (A)Project 19: Investigating How Temperature AffectsAlkaline <strong>Fuel</strong> <strong>Cell</strong> Per<strong>for</strong>manceAlkaline mini fuel cell (<strong>Fuel</strong> <strong>Cell</strong> Store P/N:530709)● Potassium hydroxide (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 500200)● Multimeter (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 596007)●●●●KettleIce cubesThermometerMethanolIn this experiment, we are going to change <strong>the</strong>temperature of our alkaline fuel cell and see how itaffects <strong>the</strong> per<strong>for</strong>mance of <strong>the</strong> fuel cell. You need alarge bowl in which you can immerse <strong>the</strong> bottom of68
<strong>the</strong> fuel cell. We are going to use ice and hot water tocontrol <strong>the</strong> temperature that <strong>the</strong> fuel cell is exposedto. We are going to create a range of temperaturesbetween 0° C (32° F) and 50° C (122° F).You should not heat <strong>the</strong> fuel cell above 50° C(122° F) as permanent damage to your fuel cellcould result.We are going to use 10 ml of methanol solution<strong>for</strong> fuel. First of all, stick <strong>the</strong> bottle of methanol inwith your ice cubes to prechill <strong>the</strong> solution.Connect <strong>the</strong> ammeter directly across <strong>the</strong> terminalsof <strong>the</strong> fuel cell. Use <strong>the</strong> <strong>the</strong>rmometer to take aFigure 6-24Insert <strong>the</strong> <strong>the</strong>rmometer here.Table 6-5Effect of temperature on AFC per<strong>for</strong>mance.Temperaturetemperature reading and note <strong>the</strong> temperature inTable 6-5. Cross out ei<strong>the</strong>r Celsius or Fahrenheit,depending on what scale you are using. Onceyou have taken your readings, plot <strong>the</strong>m inFigure 6-25.Figure 6-25temperatures.°C/°F°C/°F°C/°F°C/°F°C/°FVoltage (V)VVVVVPer<strong>for</strong>mance graph of AFC at differentProject 19: Alkaline <strong>Fuel</strong> <strong>Cell</strong> Per<strong>for</strong>mance69
Project 20: Investigating AFC PoisoningProject 20: Investigating AFC Poisoning●●●●●●●VinegarBicarbonate of sodaLimewaterErlenmeyer flask (side tap)Thistle tube with bungSwan neck tubeDishFigure 6-26The alkaline limewater reacts with <strong>the</strong> carbon dioxide.In this experiment, we are going to look at <strong>the</strong>poisoning of AFC electrolytes. One of <strong>the</strong> problemswith AFC fuel cells is that <strong>the</strong>y are very sensitiveto impurities in <strong>the</strong> air that is supplied to <strong>the</strong>m, asaqueous alkaline solutions will absorb carbondioxide.In this experiment, we are going to look at howan aqueous alkaline solution can be “poisoned” bycarbon dioxide, but first we need to make somecarbon dioxide.We are going to make our CO 2by reactingvinegar with bicarbonate of soda. It will fizz <strong>for</strong> abit and produce a gas, which is our “carbondioxide” that we are going to use to poison ourelectrolyte.Our alkaline electrolyte that we are going topoison is limewater, which is saturated calciumhydroxide solution.70
●Alkaline mini fuel cell (<strong>Fuel</strong> <strong>Cell</strong> Store P/N:530709)● Potassium hydroxide (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 500200)● Sodium borohydride (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 560109)● Multimeter (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 596007)In this experiment, we are going to block <strong>the</strong>passage of oxygen to <strong>the</strong> fuel cell, and see whe<strong>the</strong>rit can continue to function. Set up <strong>the</strong> fuel cell asin <strong>the</strong> previous experiments, with ei<strong>the</strong>r methanolor sodium borohydride as <strong>the</strong> fuel. Then, to <strong>the</strong>inside of <strong>the</strong> red cathode, add a small amount ofdistilled water, just enough to cover <strong>the</strong> cathodeelectrode. When taking measurements, you shouldfind that <strong>the</strong> fuel cell ceases to produce power.●Project 21: Investigating <strong>the</strong> AFC’s Need <strong>for</strong> OxygenFigure 6-27ConclusionThe water blocks oxygen.This proves <strong>the</strong> need <strong>for</strong> oxygen, at <strong>the</strong> cathode,<strong>for</strong> <strong>the</strong> fuel cell’s reaction to proceed.Project 22: Investigating Different Gases at <strong>the</strong> AnodeAlkaline mini fuel cell (<strong>Fuel</strong> <strong>Cell</strong> Store P/N:530709)● Potassium hydroxide (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 500200)● Sodium borohydride (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 560109)● Multimeter (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 596007)●●Selection of gasesBung and tubeIf you have access to a range of different gases,from say a school science department, you canintroduce different gases to <strong>the</strong> fuel cell’s cathode,and see how <strong>the</strong> reaction proceeds. The cleverdesign of <strong>the</strong> mini fuel cell anode means that youcan take a suitably sized rubber bung, with a holedrilled through to allow a pipe to pass through, andintroduce different gases to <strong>the</strong> fuel cell’s cathode,as shown in Figure 6-26.Compare how <strong>the</strong> AFC per<strong>for</strong>ms when usingpure oxygen to using ordinary air. You now knowhow to produce carbon dioxide—so try it, and ifProject 21: Investigating <strong>the</strong> AFC’s Need <strong>for</strong> Oxygen71
you have access to any laboratory gases, try <strong>the</strong>mtoo—try introducing hydrogen to <strong>the</strong> cathode.Project 23: Investigating <strong>the</strong> Rate of ReactionConclusionYou should conclude that <strong>the</strong> fuel cell needs oxygenin order to function, and that it per<strong>for</strong>ms betterwhen fed with a supply of pure oxygen than whenfed with air.●Alkaline mini fuel cell (<strong>Fuel</strong> <strong>Cell</strong> Store P/N:530709)● Potassium hydroxide (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 500200)● Sodium borohydride (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 560109)● Multimeter (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 596007)●●●●●●●●Bung and tubeLength of rubber hosePipetteVariable resistorConnection wiresStopwatchThermometerCalculatorFigure 6-28 A bung and pipe allow you to introducedifferent gases to <strong>the</strong> AFC’s anode.Project 23: Investigating <strong>the</strong> Rate of Reaction (OxygenConsumption) of an AFCWe can use <strong>the</strong> bung arrangement from <strong>the</strong> lastexperiment, with a short extension pipe, and agraduated tube to measure <strong>the</strong> rate of reactionhappening inside <strong>the</strong> fuel cell. You should be ableto make a piece of graduated pipe out of an oldpipette.The experiment is as follows. Set up <strong>the</strong> fuel cellwith connection to an ammeter and a variableresistance all in series. Now, insert <strong>the</strong> bung into<strong>the</strong> cathode of <strong>the</strong> fuel cell, ensuring a tight seal.Then take <strong>the</strong> piece of pipette and insert it into oneend of a piece of rubber tubing, and push <strong>the</strong> o<strong>the</strong>rover <strong>the</strong> length of pipe sticking out of <strong>the</strong> bung.The end of <strong>the</strong> pipette can be immersed in a smallbeaker of water. Figure 6-27 illustrates this.72
Figure 6-29The oxygen consumption measurement apparatus.As <strong>the</strong> AFC consumes oxygen as a result of <strong>the</strong>reaction, oxygen will be sucked out of <strong>the</strong> voidbetween <strong>the</strong> cathode and <strong>the</strong> end of <strong>the</strong> pipettedipped in <strong>the</strong> water. As <strong>the</strong> AFC consumes oxygen,water will be sucked up <strong>the</strong> pipette allowing us totake measurements of how much oxygen has beenconsumed.You should set <strong>the</strong> variable resistor so that itregisters a reading on <strong>the</strong> ammeter—currentdoes need to be drawn in order <strong>for</strong> oxygen to beconsumed.When you dip <strong>the</strong> pipette pipe in <strong>the</strong> water, <strong>the</strong>end of <strong>the</strong> tube will be full of air below <strong>the</strong> level of<strong>the</strong> water. As <strong>the</strong> AFC consumes oxygen, <strong>the</strong> waterlevel in <strong>the</strong> tube will rise. When it reaches <strong>the</strong>same height as <strong>the</strong> water in <strong>the</strong> beaker, start <strong>the</strong>stopwatch.Using <strong>the</strong> measurements on <strong>the</strong> pipette tube, weare going to time how long it takes <strong>for</strong> a volume of1 cm 3 (1 ml) of gas to be consumed. You can adjust<strong>the</strong> variable resistor, as <strong>the</strong> gas is being consumedin order to maintain a constant current flowingthrough <strong>the</strong> fuel cell. Once you have timed <strong>the</strong>consumption of 1 cm 3 of gas, empty <strong>the</strong> end of <strong>the</strong>tube dipped in <strong>the</strong> water, and repeat <strong>the</strong> experimentagain. Do <strong>the</strong> experiment three times, and enter <strong>the</strong>values in Table 6-8.Now, work out <strong>the</strong> average of <strong>the</strong> threereadings, add <strong>the</strong>m toge<strong>the</strong>r, and divide <strong>the</strong>total by three.Figure 6-30<strong>the</strong> reaction.Using a stopwatch, you can easily timeProject 23: Investigating <strong>the</strong> Rate of Reaction73
Project 23: Investigating <strong>the</strong> Rate of ReactionTable 6-6Three readings <strong>for</strong> time taken to consume 1 cm 3of oxygen.Reading 1Reading 2Reading 3Key dataTime (s)We’re going to do some sums now, and itmakes it a lot easier if we use “standard <strong>for</strong>m”<strong>for</strong> notation. If you are not familiar withstandard <strong>for</strong>m/scientific notation, use whateveryou prefer. If you think you might need toswot up a bit, Wikipedia is always a goodplace to start looking: en.wikipedia.org/wiki/Scientific_notation.Now take <strong>the</strong> <strong>the</strong>rmometer, and note <strong>the</strong> ambienttemperature of <strong>the</strong> room. We’re going to need toconvert this into Kelvins, so if you are working indegrees Fahrenheit, convert to degrees Celsius, and<strong>the</strong>n once you have <strong>the</strong> figure in degrees Celsius,add 273 to convert into Kelvins.Unless you know better (say you are on <strong>the</strong>top of a mountain), <strong>the</strong> atmospheric pressure canbe assumed to be 100 kilopascals (100 kPa)or 1.0 × 10 5 Pa.Now, remember we consumed 1 cm 3 ofoxygen—we need this figure to be in “meterscubed,” so 1.0 × 10 −6 m 3 should do <strong>the</strong> trick!Now, <strong>the</strong> next figure is something you areunlikely to know—it is called <strong>the</strong> gas constant,and it is <strong>the</strong> number that makes this equation work.For <strong>the</strong> SI units that we are using, <strong>the</strong> constant is8.314472 m 3·Pa·K −1·mol −1 .sssThe Ideal Gas Law says that PV = nRT where Pis absolute pressure, V = volume of gas,n = number of moles, R = <strong>the</strong> gas constant andT = temperature. We can rearrange this to find out<strong>the</strong> number of moles of oxygen:N = PV/RTNow, we want to know <strong>the</strong> number of moleculesof oxygen—remember Avogadro’s number? 6.02 ×10 23 —multiply this by <strong>the</strong> figure you obtained <strong>for</strong><strong>the</strong> number of moles.Next, we want to find <strong>the</strong> charge, in Coloumbs,that flowed around <strong>the</strong> circuit, so remember Q(charge, coloumbs) = A (current, amps) ×t (time, seconds)—as a hint, remember that youmight need to convert current readings from mAinto A.Now comes <strong>the</strong> clever bit—you should nowknow:●●How many molecules of oxygen were usedHow many electrons flowed around <strong>the</strong> circuitDivide <strong>the</strong> number of electrons that flowed around<strong>the</strong> circuit by <strong>the</strong> amount of oxygen moleculesconcerned.Your figure should come out as around 4!ConclusionFrom this experiment, we can see that four electronsare produced <strong>for</strong> every molecule of oxygen consumed.We also learn that consumption of oxygenis directly proportional to power produced.If your thirst <strong>for</strong> knowledge about alkaline fuelcells is truly inexhaustible, you might want tocheck out some of <strong>the</strong>se links, which make goodsources of research <strong>for</strong> science fair projects,reports, essays, you name it!—Contd74
Apollo Energy Systems—AFC manufacturerhttp://www.apolloenergysystems.com/Astris Energy—AFC manufacturerwww.astris.ca/Cenergie—AFC manufacturerwww.cenergie.com/ENECO—AFC manufacturerwww.eneco.co.uk/fuel<strong>Cell</strong>s.htmlIndependent Power—AFC manufacturerwww.independentpower.bizIntensys—AFC manufacturerwww.intensys.comHomepage of Dr John Varcoe from <strong>the</strong> Universityof Surrey, who is doing very cool things withAFCsmypages.surrey.ac.uk/chs1jv/Project 23: Investigating <strong>the</strong> Rate of Reaction75
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Chapter 7PEM <strong>Fuel</strong> <strong>Cell</strong>sWhat is a PEM fuel cell? Well, it all depends onwho you ask! Some will call <strong>the</strong>m “plastic electrolytemembrane” fuel cells, while o<strong>the</strong>rs will call<strong>the</strong>m “proton exchange membrane” fuel cells.Whatever you call <strong>the</strong>m, PEM fuel cells are veryversatile, with <strong>the</strong> advantage that <strong>the</strong>y will happilywork at low temperatures.This is what makes <strong>the</strong>m useful <strong>for</strong> our experimentationpurposes—we can play with <strong>the</strong>m athome at room temperatures, as opposed to some of<strong>the</strong> high-temperature fuel cells in this book whichrequire searing heat <strong>for</strong> <strong>the</strong>ir operation.As with all our fuel cells, electrochemicalreactions are taking place inside <strong>the</strong>m, which release<strong>the</strong> energy produced as a result of <strong>the</strong> oxidation ofhydrogen in <strong>the</strong> <strong>for</strong>m of electricity. This is opposedto releasing it by oxidation in <strong>the</strong> <strong>for</strong>m of combustion,which is horribly inefficient.One of <strong>the</strong> disadvantages of PEM fuel cells isthat <strong>the</strong>y are easily poisoned by carbon monoxide,and metal ions. This makes <strong>the</strong>m very sensitiveto hydrogen that is not pure—and with fuel cells,damage can be expensive to repair!How do PEM fuel cellswork?Take a look at Figure 7-1, and we’ll slowly workthrough <strong>the</strong> operation of a PEM fuel cell. We cansee <strong>the</strong> cell represented schematically in thisdiagram.You can see <strong>the</strong> hydrogen entering on <strong>the</strong> anodeside of <strong>the</strong> fuel cell, <strong>the</strong> oxygen entering on <strong>the</strong>cathode side of <strong>the</strong> fuel cell, and <strong>the</strong> membrane in<strong>the</strong> middle. The membrane is coated with catalyston both sides.We are going to break <strong>the</strong> process down into aseries of steps. In reality, this is a continuousFigure 7-1The proton exchange.77Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
Figure 7-2Hydrogen enters <strong>the</strong> fuel cell.process which is taking place; however, looking atit in stages, ra<strong>the</strong>r than all at once, helps us tounderstand it.We can see, in Figure 7-2, <strong>the</strong> hydrogen fuelentering <strong>the</strong> fuel cell.When it reaches <strong>the</strong> proton exchange membrane,<strong>the</strong> catalyst splits it into protons and electrons. Theprotons begin to cross <strong>the</strong> membrane, while <strong>the</strong>electrons make <strong>the</strong>ir way around <strong>the</strong> circuit (seeFigure 7-3).As this is going on, oxygen is also entering <strong>the</strong>fuel cell on <strong>the</strong> cathode side.As this process is happening, <strong>the</strong> protons aremigrating across <strong>the</strong> solid electrolyte PEM membrane,while <strong>the</strong> electrons are journeying around<strong>the</strong> circuit (Figure 7-5). They all meet up at <strong>the</strong>cathode.When <strong>the</strong>y reach <strong>the</strong> cathode, <strong>the</strong> catalystcoating helps <strong>the</strong> oxygen, protons, and electronsto combine to <strong>for</strong>m water, as shown inFigure 7-6.Now, let’s look at <strong>the</strong> components of <strong>the</strong> cell,and get to know <strong>the</strong> PEM fuel cell by taking oneapart, and building a small fuel cell kit.PEM <strong>Fuel</strong> <strong>Cell</strong>sFigure 7-3The hydrogen is split into protons and electrons.78
PEM <strong>Fuel</strong> <strong>Cell</strong>sFigure 7-4Oxygen enters <strong>the</strong> fuel cell.Figure 7-5The electrons make <strong>the</strong>ir way around <strong>the</strong> circuit.Figure 7-6The electrons, protons, and oxygen combine to <strong>for</strong>m water.
Let’s start with <strong>the</strong>membraneThe membrane is <strong>the</strong> particularly clever piece ofour PEM fuel cell—so clever, in fact, that I wonderwhy <strong>the</strong>y don’t call it a mem-brain!In our PEM fuel cell, it is <strong>the</strong> membrane thatdoes all <strong>the</strong> hard work, allowing certain reactionsto take place, while preventing o<strong>the</strong>rs.To understand exactly how it works, let’s takea closer look at what happens inside <strong>the</strong>membrane.Take a look at Figure 7-7.OK, starting in <strong>the</strong> bottom left of Figure 7-7, wecan see what looks like a sandwich. On ei<strong>the</strong>r side,we have our electrodes—<strong>the</strong> anode and <strong>the</strong>cathode, and in <strong>the</strong> middle, we have a couple ofslices of gas diffusion membrane, and <strong>the</strong>n, <strong>the</strong>best bit of all, our MEA!Now, move to <strong>the</strong> magnifying glass at <strong>the</strong> bottomof <strong>the</strong> image:You see <strong>the</strong> gray line running down <strong>the</strong> middle—well, that is our “Nafion” membrane—think of itlike a cookie with chocolate chips on both sides.The cookie dough is <strong>the</strong> special plastic our fuelcell is made from. The gray blobs ei<strong>the</strong>r side, thatlook like chocolate chips, are <strong>the</strong> gas diffusionlayers which are bonded to ei<strong>the</strong>r side of <strong>the</strong>Nafion membrane. Where <strong>the</strong> “chocolate chips”meet <strong>the</strong> cookie dough, we have our platinumcatalyst. This can be seen more closely in <strong>the</strong> twomagnifying glasses at <strong>the</strong> top of Figure 7-7—youwill see that one magnifying glass concentrates on<strong>the</strong> anode, while one examines <strong>the</strong> cathode.Now, our reactions take place at <strong>the</strong> pointwhere <strong>the</strong> cookie dough (Nafion), chocolatechips (GDL), platinum catalyst (<strong>the</strong> small whitedots between <strong>the</strong> chocolate chips and cookiedough—let’s call <strong>the</strong>se “sprinkles”), and gas meet.The hydrogen gas comes in at one side, permeatesPEM <strong>Fuel</strong> <strong>Cell</strong>sFigure 7-7What goes on in <strong>the</strong> middle of <strong>the</strong> PEM membrane!80
through <strong>the</strong> GDL, and <strong>the</strong> sprinkles (platinum)catalyze a reaction (and this is where <strong>the</strong> cookie[analogy] crumbles), where <strong>the</strong> hydrogen passesthrough <strong>the</strong> cookie (Nafion), <strong>the</strong> electronspass through <strong>the</strong> chocolate chips (GDL), where<strong>the</strong>y are reunited at <strong>the</strong> o<strong>the</strong>r side of <strong>the</strong> cookie.Now, remember we said <strong>the</strong>re were two sides tothis cookie? (Yes … even Millies make mistakes),<strong>the</strong>re are more sprinkles (platinum catalyst) on <strong>the</strong>o<strong>the</strong>r side, so, as our electrons are conductedthrough <strong>the</strong> chocolate chips to meet <strong>the</strong> cookiedough (which protons have just passed through),<strong>the</strong> sprinkles catalyze ano<strong>the</strong>r reaction between <strong>the</strong>protons, <strong>the</strong> electrons and … introducing …oxygen from <strong>the</strong> o<strong>the</strong>r side of <strong>the</strong> cookie. They allget toge<strong>the</strong>r to produce water!Now, clearly we are not using cookies, andchocolate chips and sprinkles—<strong>the</strong> materials used infuel cell construction are much more sophisticated(unless you evaluate <strong>the</strong>m by taste—don’t try it kids).We’re going to look at <strong>the</strong> materials used in alittle more depth!Chocolate chipsWell, although it looks like chocolate chips from <strong>the</strong>side, in reality, <strong>the</strong> woven carbon cloth of <strong>the</strong> GDL ismore like a closely woven lattice of chocolate sauce.It needs to have holes to allow <strong>the</strong> hydrogen topenetrate through to <strong>the</strong> cookie dough (Nafionmembrane); however, it still needs to providesufficient surface area and support to <strong>the</strong> sprinklesunderneath to allow <strong>the</strong> reactions to take place.SprinklesWe may use slightly different materials <strong>for</strong> <strong>the</strong>sprinkles on each side of <strong>the</strong> fuel cell. Whilehydrogen is relatively easy to split, <strong>the</strong> oxygenis a little more of a challenge. Platinum is a goodmaterial <strong>for</strong> this application, however, with advancesin material science, we may find more efficient andcheaper catalysts to replace <strong>the</strong> sprinkles on bothsides of <strong>the</strong> membrane.All you wanted to everknow about sulfonatedtetrafluorethylenecopolymers . . .. . . and probably quitea lot you didn’t!Our PEM fuel cells wouldn’t exist if it weren’t <strong>for</strong>rapid advances in polymer technology that allowed<strong>the</strong> creation of <strong>the</strong> “solid electrolyte”.Nafion was discovered in <strong>the</strong> late 1960s by aman called Wal<strong>the</strong>r Grot at DuPont. Nafionhas enabled <strong>the</strong> construction of <strong>the</strong> PEM fuel cell,due to its unique chemical properties.There are a couple of things that fuel cell fansreally like about Nafion:Mechanically it is very stable—it’s not going tocrumble when you look away, it’s flexible andwon’t crack—it’s a little flimsy, but treat itwith respect and it will be reliable.Chemically it is tolerant of a wide range ofchemicals and does not react or degradereadily (apart from with alkali metals).Thermally it is tolerant of <strong>the</strong> temperatureexperiences in PEM fuel cells.It is stable to changes in temperature.In Figure 7-8, we can see <strong>the</strong> Nafion unit: <strong>the</strong>top right is <strong>the</strong> Teflon backbone of <strong>the</strong> Nafion(<strong>the</strong> same material you find in your nonstickfrying pans), while <strong>the</strong> bottom right shows <strong>the</strong>sulfonic acid group that allows <strong>for</strong> <strong>the</strong> conductionof protons.It’s hard to pin down <strong>the</strong> exact nature of Nafionstructure, although one suggestion is <strong>the</strong> clustermodel shown in Figure 7-9: Look at <strong>the</strong> sulfonicacid groups around <strong>the</strong> outside.The SO -3groups (or sulfonic acid) groups in <strong>the</strong>Nafion can jump from one side of <strong>the</strong> membraneto <strong>the</strong> o<strong>the</strong>r. This allows <strong>the</strong>m to transport protonsPEM <strong>Fuel</strong> <strong>Cell</strong>s81
Figure 7-8Nafion chemical structure.from one side of our PEM fuel cell to <strong>the</strong> o<strong>the</strong>r—a crucial facet of <strong>the</strong> PEM fuel cell’s operation.What’s also really clever about <strong>the</strong>se littlesulfonic acid groups is that <strong>the</strong>y only allow <strong>the</strong>passage of cations—<strong>the</strong> anions and electrons canjust get lost if <strong>the</strong>y think <strong>the</strong>y’re crossing thissulfonated tetrafluorethylene copolymer membrane!However, as we know, <strong>the</strong> electrons might have totake a slightly more circuitous route (OK, so it’s abad pun!), but on <strong>the</strong>ir journey, <strong>the</strong>y do usefulwork <strong>for</strong> us.So <strong>the</strong> sulfonic acid groups act as gatekeepers inour fuel cell, only letting those with proton passportsacross <strong>the</strong> border, while <strong>the</strong> electrons have to take<strong>the</strong> long way home.I often lay awake wondering where we would bewithout sulfonic acid groups …Flow fieldsIn some of our smaller fuel cells, we can make dowithout a fully blown flow field, and get awaywith a piece of carbon cloth or paper to do <strong>the</strong>same job—just spread <strong>the</strong> hydrogen over <strong>the</strong>surface of <strong>the</strong> MEA, while allowing electrons to betransferred from <strong>the</strong> GDM to <strong>the</strong> electrodes.However, once we start looking at more sophisticatedfuel cells, carbon cloth and paper just doesn’tcut <strong>the</strong> mustard—we need to look at more sophisticatedmethods of spreading <strong>the</strong> hydrogen thinlyand evenly over <strong>the</strong> surface of <strong>the</strong> MEA, on <strong>the</strong>anode, and ensuring that sufficient amounts ofoxygen come into contact with <strong>the</strong> MEA on <strong>the</strong>cathode side.PEM <strong>Fuel</strong> <strong>Cell</strong>sFigure 7-9Nafion cluster model.82
PEM <strong>Fuel</strong> <strong>Cell</strong>sFigure 7-10Straight flow field.Figure 7-12Serpentine flow field.The type of flow field we select will depend on<strong>the</strong> flow characteristics that we desire. There isongoing research into how <strong>the</strong> design of <strong>the</strong> flowfield can affect <strong>the</strong> efficiency of <strong>the</strong> fuel cell, withscientists working to reconcile two competingfactors—<strong>the</strong> need to spread hydrogen over <strong>the</strong>surface of <strong>the</strong> MEA, while still maintaining goodelectrical contact with <strong>the</strong> surface of <strong>the</strong> MEA.There are a few different patterns that we canlook at, in Figures 7-10 to 7-13.The simplest of <strong>the</strong>m all is <strong>the</strong> straight flowfield, which has a place <strong>for</strong> gas to be input, andplace <strong>for</strong> excess gas to escape, and a straight gridof lines between <strong>the</strong> two sides.Getting slightly more advanced, in Figure 7-11,<strong>the</strong> interdigitated flow field has interlocking fingersof hydrogen supply and return lines. However,<strong>the</strong>se are not connected directly, so <strong>the</strong> hydrogenmust make a path to <strong>the</strong> MEA be<strong>for</strong>e spare hydrogencan be returned.Figure 7-11Interdigitated flow field.Figure 7-13Spiral flow field.83
The serpentine flow field is like a long undulatingsnake—<strong>the</strong> hydrogen has to make a path <strong>for</strong>wardand backward, <strong>for</strong>ward and backward, be<strong>for</strong>e itreaches <strong>the</strong> return. Hopefully, by this time, muchof <strong>the</strong> hydrogen has had its chance to cross <strong>the</strong>MEA’s membrane.Finally, ano<strong>the</strong>r variation is <strong>the</strong> spiral flow field—itdoes exactly what it says—spirals in, <strong>the</strong>n spirals out.Of course, manufacturers are developing newvariations of <strong>the</strong>se flow fields every day. You mighteven like to turn to <strong>the</strong> project entitled “MakingYour Own MEAs” on page 126, and look at howyou can advance <strong>the</strong> state of <strong>the</strong> art in fuel celltechnology.Project 24: Disassembling a <strong>Fuel</strong> <strong>Cell</strong>●●Project 24: Disassembling a <strong>Fuel</strong> <strong>Cell</strong>A dismantleable fuel cell, e.g., <strong>Fuel</strong> <strong>Cell</strong> Store P/N:80044Supplied Allen key and spannerThe fuel cell kit will come with a spanner andAllen key, that fits <strong>the</strong> fixings used to aid assemblyand disassembly. You can see in Figure 7-15 that itis relatively easy to remove <strong>the</strong> fixings.When all four nuts and bolts have been removed,ensure that you keep <strong>the</strong>m somewhere safe, and havea flat, clean surface to work on, as in Figure 7-16.By taking apart a fuel cell, we can learn a lot aboutits construction, which will help us to relate some of<strong>the</strong> <strong>the</strong>ory, here on <strong>the</strong> page, to <strong>the</strong> practical aspectsof constructing a fuel cell. If you have any thoughts ofscratch building your own fuel cell, it is a good ideato start with a commercially available dismantleablefuel cell, to get to grips with <strong>the</strong> construction.However, be warned—although such fuel cellsare designed <strong>for</strong> being taken apart and reassembled,<strong>the</strong>y can still be damaged if you do not takesufficient care.Figure 7-14 shows us a dismantleable fuel cell. Figure 7-14 The complete dismantleable fuel cell.84
Figure 7-15 The supplied Allen key and spanner canbe used to disassemble <strong>the</strong> fuel cell.Lay <strong>the</strong> parts out so that you can see what is happeningas you take <strong>the</strong> fuel cell apart.When you’ve got all <strong>the</strong> fixings away, you cancarefully remove <strong>the</strong> plastic end-plates, as shownin Figure 7-17—this will expose <strong>the</strong> electrodeassembly in <strong>the</strong> centre of <strong>the</strong> fuel cell.Lay out <strong>the</strong> end-plates and electrode assembly,as in Figure 7-18.The electrode assembly is what is shown inFigure 7-19—it comprises of two electrodes,<strong>the</strong> gas diffusion membrane, and <strong>the</strong> membraneelectrode assembly. You now have to decide whe<strong>the</strong>ryou want to take this component apart—whileeducational, you run <strong>the</strong> risk of damaging <strong>the</strong> fuelcell at this point if you are not careful.Carefully remove one electrode and <strong>the</strong>n <strong>the</strong> next,exposing <strong>the</strong> MEA. You will be left with threecomponents, as shown in Figures 7-20 and 7-21.Ensure that you do not touch <strong>the</strong> MEA, or <strong>the</strong>surfaces that come into contact with it.The next step is OK if you have spare MEAs, or<strong>the</strong> money to shell out to buy a new one—you canlearn just as much by looking at <strong>the</strong> pictures.However, if you do decide to take apart your ownMEA, don’t cry when your fuel cell refuses towork afterwards. This is maybe a step to carry outwhen you’ve had your fun with <strong>the</strong> dismantleablefuel cell and/or worn out <strong>the</strong> MEA!If you wish, you can use a scalpel to carefullydeconstruct <strong>the</strong> MEA—it will render it uselessthough. Figure 7-22 illustrates <strong>the</strong> components of<strong>the</strong> MEA well. With one ei<strong>the</strong>r end, you can see<strong>the</strong> plastic gaskets that support <strong>the</strong> MEA, with <strong>the</strong>carbon GDMs ei<strong>the</strong>r side of <strong>the</strong> central MEA.Project 24: Disassembling a <strong>Fuel</strong> <strong>Cell</strong>Figure 7-16The fuel cell with fixings removed.85
Project 24: Disassembling a <strong>Fuel</strong> <strong>Cell</strong>Figure 7-17 Removing <strong>the</strong> end plate.Figure 7-18 The end plates and electrode assembly.Figure 7-19 The electrode assembly. Figure 7-20 One electrode removed.86
Figure 7-21Figure 7-22Two electrodes removed.The MEA deconstructed.Project 24: Disassembling a <strong>Fuel</strong> <strong>Cell</strong>Figure 7-23Diagram showing <strong>the</strong> components of your dismantleable fuel cell.87
Relate <strong>the</strong> deconstructed MEA to <strong>the</strong> earlierdiagrams in <strong>the</strong> chapter, compare <strong>the</strong> schematicmodels of <strong>the</strong> fuel cells earlier in this chapter, andrelate it to your practical experience of taking <strong>the</strong>fuel cell apart.Figure 7-23 may be of help, whenconsidering how <strong>the</strong> different layers of <strong>the</strong> PEMfuel cell go toge<strong>the</strong>r—providing an explodeddiagram.Project 25: Changing MEA Platinum Loading●Dismantleable fuel cell—extension kit (<strong>Fuel</strong> <strong>Cell</strong>Store P/N: 80044)The per<strong>for</strong>mance of a PEM fuel cell will depend tosome extent on <strong>the</strong> amount of platinum catalystsandwiched between <strong>the</strong> Nafion membrane andFigure 7-24Project 25: Changing MEA Platinum LoadingDifferent membrane electrode assemblies.<strong>the</strong> GDL. The more platinum, <strong>the</strong> more sites <strong>the</strong>reare <strong>for</strong> reactions to take place, and so <strong>the</strong> output of<strong>the</strong> fuel cell should be higher.One way that you can experiment with this iswith <strong>the</strong> dismantleable fuel cell. The extension kitcomes with a couple of extra MEAs, with differentplatinum loadings to <strong>the</strong> standard one fitted in <strong>the</strong>fuel cell. You can substitute <strong>the</strong>se MEAs, reassemble<strong>the</strong> fuel cell, and compare how <strong>the</strong> cell per<strong>for</strong>msunder different conditions.88
●Project 26: Experimenting with Oxygen and AirDismantleable fuel cell with oxygen and airend-plates (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 80044)You will realize that oxygen is only a componentof <strong>the</strong> air that we brea<strong>the</strong>. In fact, our atmosphereis comprised of 78% nitrogen and around 20.95%oxygen.It should <strong>the</strong>re<strong>for</strong>e follow that a fuel cell runningon pure oxygen will per<strong>for</strong>m in a superior mannerto one running just on air.We can experiment with this proposition, byusing a dismantleable fuel cell. Remember, with agood experiment, we want to control as manyfactors as possible, to reduce <strong>the</strong> chance of errorarising from o<strong>the</strong>r sources. In practice, this meansthat we want to keep as much of our fuel cell <strong>the</strong>same as possible—keeping <strong>the</strong> same MEA, GDMand electrodes, but changing <strong>the</strong> oxygen to air orvice versa.When we are running our fuel cell on air, we doit at atmospheric pressure. We want to maximize<strong>the</strong> amount of air reaching our fuel cell, as it is notbeing <strong>for</strong>ced under pressure through a pipe. Sowhen running our fuel cell on air, we change <strong>the</strong>Figure 7-25Air fuel cell end-plate.end-plate with pipe connections, <strong>for</strong> one with anopen grate that allows easy passage of air.When we feed oxygen into a fuel cell, we needto do it under a very small pressure, so we can usean end-plate like Figure 7-26, which has a pair ofbarbs to feed and return <strong>the</strong> oxygen to our fuelcell.Set your fuel cell up with both air and oxygenend-plates, and take measurements to compare <strong>the</strong>per<strong>for</strong>mance of <strong>the</strong> cells using oxygen and air.Project 26: Experimenting with Oxygen and Air89
Project 27: Building Your Own Mini <strong>Fuel</strong> <strong>Cell</strong>Figure 7-26Oxygen fuel cell end-plate.Project 27: Building Your Own Mini <strong>Fuel</strong> <strong>Cell</strong>Consumer electronics devices are becoming increasinglyminiaturized. You only have to look at <strong>the</strong>suitcase mobile phones of <strong>the</strong> 1980s with bricks<strong>for</strong> handsets, and compare <strong>the</strong>m to today’s phones,which can outsmall a bar of soap <strong>for</strong> evidence ofthis trend.One of <strong>the</strong> limiting factors in miniaturizingelectronic devices has been <strong>the</strong> power technology.Early mobile phones were necessarily large—notonly because <strong>the</strong> electronics inside were big, butalso because <strong>the</strong> batteries needed to power <strong>the</strong>mwere commensurately massive.Improvements in battery technology, and <strong>the</strong>improving energy efficiency of electronic devicesis leading to smaller and smaller powerpacks;however, <strong>the</strong>re is a complex tradeoff with size <strong>for</strong>operating life. Smaller batteries mean that you cantalk <strong>for</strong> less time on your phone, listen to lesstunes be<strong>for</strong>e having to recharge, or watch lessmovies on your portable media player be<strong>for</strong>e it isback to <strong>the</strong> docking station.<strong>Fuel</strong> cells potentially offer all kinds of excitingpossibilities <strong>for</strong> powering portable electronicdevices.● Mini fuel cell (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 531907)●●Pair of handsCotton gloves (optional)The mini fuel cell is a really clever construction.The manufacturers have used <strong>the</strong> gasket material tokeep all <strong>the</strong> parts of <strong>the</strong> fuel cell toge<strong>the</strong>r, withsimple folding required <strong>for</strong> assembly.90
Figure 7-27The mini fuel cell laid out.You can see, <strong>the</strong> mini fuel cell laid out in all itsglory in Figure 7-27. We can see by <strong>the</strong> per<strong>for</strong>atedmetal electrodes looking at <strong>the</strong> ends. You will seethat <strong>the</strong> metal is “dished in” slightly—this is toensure that it makes good contact with <strong>the</strong> GDMwhen <strong>the</strong> fuel cell is folded. You can see <strong>the</strong> twotiny GDLs moving into <strong>the</strong> next two squares. Thisprovides electrical contact between <strong>the</strong> electrodesand <strong>the</strong> MEA, while allowing <strong>the</strong> hydrogen (anddon’t <strong>for</strong>get <strong>the</strong> oxygen) gas to diffuse toward <strong>the</strong>MEA .… And finally, our central square is <strong>the</strong>membrane electrode assembly—<strong>the</strong> little patchwhere all <strong>the</strong> exciting reactions take place!Figure 7-28 Peeling <strong>the</strong> backing paper from <strong>the</strong>adhesive gasket.Start at one end, and work your way along <strong>the</strong>mini fuel cell—<strong>the</strong> squares of brown adhesive paperare removable protective coverings <strong>for</strong> an adhesivelayer. You need to peel <strong>the</strong>se off one by one, andfold <strong>the</strong> fuel cell over in sequence, making sureyou don’t touch any of <strong>the</strong> sensitive bits of <strong>the</strong> fuelcell, <strong>for</strong> risk of poisoning <strong>the</strong> catalyst.Cotton gloves will protect <strong>the</strong> elements of <strong>the</strong>fuel cell that can be damaged, but if you’ve gotclumsy fingers like me, you’re going to struggle topeel <strong>the</strong> adhesive backings from <strong>the</strong> squares, andyou might end up getting in a mess with cottongloves stuck to <strong>the</strong> sticky bits of <strong>the</strong> fuel cell.As you remove <strong>the</strong> backing paper from <strong>the</strong>adhesive layer adjacent to one electrode, fold thatsection of <strong>the</strong> fuel cell over, and ensure that <strong>the</strong>GDM makes good contact with <strong>the</strong> electrode.Right! This step is absolutely crucial. Two thingsyou need to remember: do not touch <strong>the</strong> MEAunder any circumstances. Cotton gloves are agodsend in this respect, although when peeling off<strong>the</strong> fiddly adhesive backings, <strong>the</strong>y can also be anightmare—use your judgment and caution. Onceyou’ve teased off <strong>the</strong> adhesive backing from yourGDM, you are going to need to line up <strong>the</strong> flimsyMEA with <strong>the</strong> square of GDM. Ensure that you get<strong>the</strong>m to sit directly over each o<strong>the</strong>r <strong>for</strong> optimumper<strong>for</strong>mance. Figure 7-30 shows <strong>the</strong> fiddly job oflining <strong>the</strong>m up.OK, it’s sharp nails at <strong>the</strong> ready <strong>for</strong> <strong>the</strong> last time!Tease <strong>the</strong> final corner of that last adhesive square,and fold <strong>the</strong> fuel cell over <strong>for</strong> <strong>the</strong> last time, leavingyou with a neatly packaged little square minifuel cell.Project 27: Building Your Own Mini <strong>Fuel</strong> <strong>Cell</strong>91
Project 27: Building Your Own Mini <strong>Fuel</strong> <strong>Cell</strong>Figure 7-29Figure 7-30Figure 7-31The fuel cell once folded.Lining up <strong>the</strong> MEA.Removing <strong>the</strong> final adhesive backing.92
Figure 7-32Mini fuel cell next to a quarter <strong>for</strong> scale.Once you’ve stuck <strong>the</strong> fuel cell toge<strong>the</strong>r with <strong>the</strong>adhesive squares, you need to ensure that propercontact between all <strong>the</strong> layers is made. You willsee that all around <strong>the</strong> edge of <strong>the</strong> mini fuel cell,<strong>the</strong>re are small metal extensions to <strong>the</strong> electrode.These are folded over <strong>the</strong> opposing electrode, niceand tightly, to clamp <strong>the</strong> fuel cell assembly toge<strong>the</strong>r.Don’t worry, <strong>the</strong>y won’t short out against <strong>the</strong>opposite electrode—<strong>the</strong> plastic end-plates will stopthis from happening!And just to remind you of <strong>the</strong> wonders of <strong>the</strong>mini fuel cell’s miniaturization, check out Figure7-32, with <strong>the</strong> fuel cell next to a quarter <strong>for</strong> a senseof scale. This is what your mini fuel cell shouldlook like when finished. Note <strong>the</strong> tabs folded over.Now, you should be proud of your workmanship.Go and test it out! Grab yourself a multimeter, anda source of hydrogen. Hold <strong>the</strong> end of <strong>the</strong> hydrogentube close to <strong>the</strong> small hole in <strong>the</strong> plastic end-plateof <strong>the</strong> mini fuel cell, and watch it crank out <strong>the</strong> volts.Figure 7-33 Use a multimeter to check power isbeing produced.Yes! It really does work. To see a video of <strong>the</strong>mini fuel cell powering a “spinner” powered by<strong>the</strong> hydrogen from <strong>the</strong> H-Gen generator, checkout my video on YouTube at:www.youtube.com/watch?v=JsWfvUktNuoProject 27: Building Your Own Mini <strong>Fuel</strong> <strong>Cell</strong>93
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Chapter 8Direct Methanol <strong>Fuel</strong> <strong>Cell</strong>sOne of <strong>the</strong> problems with hydrogen is that it is alittle problematic to store. This is a concept that wewill explore in <strong>the</strong> later chapter on hydrogen storage.There is ano<strong>the</strong>r type of fuel cell, which is able toutilize methanol as a carrier of hydrogen.There are a number of advantages to this approach:methanol has a very high energy density and it canbe transported easily using existing infrastructure<strong>for</strong> moving liquid fuels.One of <strong>the</strong> problems with hydrogen is that itrequires a massive change of infrastructure. Whilethis is not impossible, it does necessitate a change.One of <strong>the</strong> advantages of <strong>the</strong> methanol fuel cell isthat <strong>the</strong> methanol can be stored and transportedusing <strong>the</strong> conventional infrastructure that is used tomove and transport o<strong>the</strong>r liquid fuels such as petrol.Because <strong>the</strong> methanol can utilize <strong>the</strong> existinginfrastructure, many believe that methanol will bea good transitionary fuel in <strong>the</strong> move over to ahydrogen economy.Warning! Methanol is TOXIC and highlyflammable.Keep methanol away from all sources of ignition.Only operate <strong>the</strong> system in an area that issufficiently ventilated to ensure that you are notexposed to high concentrations of methanolfumes.AttentionDirect methanol fuel cells require asolution of methanol in water, if <strong>the</strong>concentration of methanol is too high you willdamage <strong>the</strong> membrane in <strong>the</strong> fuel cell.Manufacturers recommend that you work withconcentrations that do not exceed 3%. In practice,this is often a little overcautious, andconcentrations around 4% can worksuccessfully. However, note that concentrationsmuch higher than this will certainly damageyour fuel cell, and concentrations over3% are not recommended <strong>for</strong>prolonged use.First aid guidelinesIf you get methanol in contact with yourskin, you will need to wash it off withcopious amounts of water, as methanol istoxic.Protect your eyes from splashes from methanol bywearing safety goggles at all times. If you doinadvertently splash even <strong>the</strong> tiniest amount ofmethanol into your eyes, you will need tothoroughly wash <strong>the</strong>m using clean water or aneyewash station, and contact a doctor immediatelyor your hospital’s ER department.Be careful not to inhale methanol fumes. If youdo, open windows, and walk outside and get some95Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
Direct Methanol <strong>Fuel</strong> <strong>Cell</strong>sfresh air. If symptoms persist, consult your doctoror your hospital’s ER department.Methanol should not be ingested. In <strong>the</strong> event thatyou do accidentally ingest some methanol, drinklots and lots of clear water and consult a doctorimmediately or your hospital’s ER department.If you feel nauseous, consult your doctor. Tell <strong>the</strong>doctor you have been working with methanol, andshow him <strong>the</strong> material’s data sheet.Direct methanol fuel cellchemistryDirect methanol fuel cells directly re<strong>for</strong>m <strong>the</strong>methanol, extracting <strong>the</strong> hydrogen, and producingcarbon dioxide with <strong>the</strong> spare carbon in <strong>the</strong>methanol. We can see methanol fuel cell chemistryin Figure 8-1.Looking to <strong>the</strong> diagram in Figure 8-2, we cansee how <strong>the</strong> methanol fuel cell is a membrane fuelcell, just like <strong>the</strong> PEM fuel cell we looked at in <strong>the</strong>previous chapter. Functionally, <strong>the</strong>y are very similar.Figure 8-1Direct methanol fuel cell chemistry.Overlay <strong>the</strong> chemical reactions that are takingplace (see Figure 8-3), and we can see water andmethanol entering toge<strong>the</strong>r at <strong>the</strong> top left, <strong>the</strong>protons being stripped of <strong>the</strong>ir electrons withcarbon dioxide, and water <strong>the</strong> resulting product.The protons pass through <strong>the</strong> membrane, <strong>the</strong> sameas in <strong>the</strong> PEM fuel cell, and <strong>the</strong> electrons passround <strong>the</strong> circuit. On <strong>the</strong> o<strong>the</strong>r side of <strong>the</strong> diagram,things are <strong>the</strong> same as we are used to seeing with<strong>the</strong> PEM fuel cell.We can see that <strong>the</strong> carbon dioxide is producedat <strong>the</strong> anode of <strong>the</strong> fuel cell.Get a good measuring cylinder, like <strong>the</strong> one inFigure 8-4, as you will need to prepare methanolsolutions of different concentrations.Figure 8-2Direct methanol fuel cell diagram.96
Figure 8-3What goes on inside a DMFC?Direct Methanol <strong>Fuel</strong> <strong>Cell</strong>sFigure 8-4A cylinder suitable <strong>for</strong> preparing different methanol concentrations.97
Project 28: Getting to Grips with <strong>the</strong> Methanol <strong>Fuel</strong> <strong>Cell</strong>●●●Project 28: Getting to Grips with <strong>the</strong> Methanol <strong>Fuel</strong> <strong>Cell</strong>DMFC fuel cell and load (e.g., DMFC and fan <strong>Fuel</strong><strong>Cell</strong> Store P/N: 550307)Prepared methanol solution—3% methanol indistilled water (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 500100)Squeezy bottleIf your fuel cell has been stored in a dry atmosphere,you may find its initial per<strong>for</strong>mance a littledisappointing. This is because <strong>the</strong> membrane needsto be hydrated. Try using a little distilled waterfirst of all to dampen <strong>the</strong> membrane, and <strong>the</strong>n fill<strong>the</strong> cell with some methanol solution.The methanol fuel cell has two holes at <strong>the</strong> topof <strong>the</strong> assembly. These holes allow you to fill <strong>the</strong>fuel cell with a prepared methanol solution. Youcan pour methanol into one hole, and <strong>the</strong> o<strong>the</strong>rhole will allow air to escape.The correct way to fill <strong>the</strong> fuel cell is to use asqueezy bottle with a narrow spout. Hold <strong>the</strong> fuelcell so that <strong>the</strong> two holes are angled, insert <strong>the</strong>squeezy bottle into one hole, and squeeze until<strong>the</strong>re is no air left in <strong>the</strong> DMFC chamber.Now pour some 3% methanol solution into<strong>the</strong> cell.The cell will take a little time to start up. It isnot unusual <strong>for</strong> it to be several minutes be<strong>for</strong>e <strong>the</strong>cell starts producing any power. Once <strong>the</strong> cellstarts producing power, it will happily run <strong>for</strong> afew hours.Once <strong>the</strong> cells stops producing power, <strong>the</strong>n <strong>the</strong>methanol has been exhausted. The cell must nowbe drained and refilled to start producing poweragain.Figure 8-5 Closeup of filling <strong>the</strong> methanol fuel cell. Figure 8-6 Filling <strong>the</strong> methanol fuel cell.98
●●●●Project 29: Decommissioning and Recommissioninga Methanol <strong>Fuel</strong> <strong>Cell</strong>Direct methanol fuel cellDistilled water1% sulfuric acid3% methanol solutionIntroductionIf a methanol fuel cell is not to be used <strong>for</strong> sometime, it should be “decommissioned” and <strong>the</strong>n“recommissioned” when you are ready to use itagain. This will ensure long life of <strong>the</strong> cell.MethodDecommissioningFlush <strong>the</strong> cell out with some distilled water thatdoes not contain methanol. Now, using a smallpiece of tape, seal <strong>the</strong> two holes. This will prevent<strong>the</strong> cell from drying out.RecommissioningIf <strong>the</strong> cell is to be used again, <strong>the</strong> tape should beremoved. First, try <strong>the</strong> cell with some 3% methanolsolution, recharge it a couple of times, and leave it<strong>for</strong> several minutes.The cell will degrade if it is left without beingused. If you find that it will not work even afterrecharging with 3% methanol, <strong>the</strong>n you will needto recommission <strong>the</strong> cell.Sulfuric acid is very nasty stuff and precautionsshould be taken to ensure that you do not get it onyour hands, in your eyes, or ingest it.Prepare some 1% sulfuric acid solution andcharge <strong>the</strong> fuel cell as you would do with methanol.Leave it <strong>for</strong> a couple of days. Then empty <strong>the</strong> acidand recharge with a 3% methanol solution. Thecell should work again.Project 29: Decommissioning and Recommissioning99
Project 30: Building a Band-Aid ® <strong>Fuel</strong> <strong>Cell</strong>Project 30: Building a Band-Aid ® <strong>Fuel</strong> <strong>Cell</strong>● 2 nice big Band-Aids ®●●Type 316 stainless steel wire cloth (<strong>Fuel</strong> <strong>Cell</strong> StoreP/N: 590663)5L DMFC MEA 5cm 2 (<strong>Fuel</strong> <strong>Cell</strong> StoreP/N: 590310)● Cotton gloves (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 591463)●3% methanol solution (<strong>Fuel</strong> <strong>Cell</strong> StoreP/N: 500100)● Multimeter (e.g., <strong>Fuel</strong> <strong>Cell</strong> Store P/N: 596107)●●ScalpelScissorsIn this experiment, we are going to build a verysimple, rough and ready, direct methanol fuel cellwith <strong>the</strong> help of a box of Band-Aids ® . I originallypublished this project in MAKE:zine, and manyfuel cell experimenters have found it a simple, easyintroduction to fuel cell technology. I really do notthink <strong>the</strong>re is a simpler way to scratch-build adirect methanol fuel cell, and get to grips with <strong>the</strong>technology.Be<strong>for</strong>e we get stuck into <strong>the</strong> nitty-gritty ofconstruction, I must share with you, esteemedreader, how this project came into being. I had justread on <strong>the</strong> net, <strong>the</strong> quote from Lawrence Burns,<strong>the</strong> GM vice president <strong>for</strong> research anddevelopment, who said, “The fuel cell offers a cure,not a Band-Aid.” Shortly after, while going to <strong>the</strong>bathroom, my eyes clapped on a box of Band-Aids,and an idea began to <strong>for</strong>m . . . The result is thisproject, which is truly a Band-Aid!Once you’ve ga<strong>the</strong>red all <strong>the</strong> parts in <strong>the</strong> list, youshould have an array of bits that resemble Figure 8-7.You need to ensure that you have suitably largeBand-Aids.Think Rite Aid or Walgreens. These are just yourbog-standard Band-Aids. Don’t get ones that areimpregnated with aloe vera or any special ointment—it will simply gunk up <strong>the</strong> works. Just get plain oldBand-Aids. You want one with a nice big area <strong>for</strong><strong>the</strong> “wound.”Remember, from <strong>the</strong> point you start peeling <strong>the</strong>adhesive film from <strong>the</strong> Band-Aid, you need to keep<strong>the</strong> surfaces that come into contact with <strong>the</strong> MEAscrupulously clean. At all times when workingwith <strong>the</strong> MEA, you will need to wear cotton glovesas shown in Figure 8-10. This is because <strong>the</strong> muckon your hands will greatly inhibit <strong>the</strong> function of<strong>the</strong> MEA.We are going to make our electrodes fromstainless steel screen. If you want to get really techieFigure 8-7The components of <strong>the</strong> Band-Aid fuel cell.100
Figure 8-8A pair of suitably sized Band-Aids.and heavy about stainless steel fly screen, <strong>the</strong>material that I used was top-notch stuff. The stainlesssteel was 318 grade, i.e., very high quality! Thescreen was 72 wires per inch in both directions, wi<strong>the</strong>ach wire being 0.0037 inch. To show you <strong>the</strong> sort ofmaterial we are referring to, look at Figure 8-11.MEA—<strong>the</strong> membrane electrodeassemblyMEA stands <strong>for</strong> “membrane electrodeassembly”—this is <strong>the</strong> bit that “does <strong>the</strong> works.”You can make your own, but <strong>the</strong>y are ra<strong>the</strong>r difficultto assemble—much simpler is to buy one that isalready made from www.fuelcellstore.com. This iswhat you get <strong>for</strong> your money: a piece of Nafion—this posh plastic is technically known as a sulfonatedtetrafluorethylene copolymer . . . Let’s look a littlemore closely at <strong>the</strong> plastic bag in Figure 8-12.The large DMFC tells you that <strong>the</strong> fuel cell is adirect methanol fuel cell—this is a variant of aproton exchange membrane fuel cell. What itessentially means is that <strong>the</strong> MEA re<strong>for</strong>ms <strong>the</strong>methanol to carbon dioxide and hydrogen withoutany external action required. It really is all cleverstuff! Looking at <strong>the</strong> panel on <strong>the</strong> right-hand sideof <strong>the</strong> label, we can see that <strong>the</strong> “active area” ofProject 30: Building a Band-Aid ® <strong>Fuel</strong> <strong>Cell</strong>Figure 8-9Unwrapping <strong>the</strong> Band-Aids.Figure 8-10damaged.Cotton gloves ensure <strong>the</strong> MEA is not101
Making <strong>the</strong> Band-Aid fuel cellProject 30: Building a Band-Aid ® <strong>Fuel</strong> <strong>Cell</strong>Figure 8-11<strong>the</strong> fuel cell—that is to say, <strong>the</strong> bit with <strong>the</strong>catalyst—is 2.3 cm × 2.3 cm, about an inch square<strong>for</strong> those using Imperial. The Nafion membraneitself is significantly larger—5.5 × 5.5 cm square,or about 2 inches square.We can see looking at <strong>the</strong> details below that <strong>the</strong>anode is coated with a mixture of platinum andru<strong>the</strong>nium, 4.0 milligram per cm 3 to be exact, while<strong>the</strong> cathode is loaded with 2.0 milligram of platinum.The membrane has a built-in gas diffusion layer ofcarbon cloth.Figure 8-12Stainless steel fly screen.Details of <strong>the</strong> MEA we are using <strong>for</strong> <strong>the</strong> Band-Aid fuel cell project.Making <strong>the</strong> Band-Aid fuel cell is a real walk in <strong>the</strong>park. All you need to do is be sure that you protect<strong>the</strong> MEA and handle it delicately, and try and ensureall surfaces remain clean.First of all, you need to cut a rectangle of wiremesh. This should be a little narrower than <strong>the</strong>smallest dimension of <strong>the</strong> wound pad of yourBand-Aid, and longer than <strong>the</strong> longest dimensionof your Band-Aid. Cut ano<strong>the</strong>r identical strip.Now, remove <strong>the</strong> protective covering from oneBand-Aid, as in Figure 8-13, and place <strong>the</strong> firstpiece of wire mesh so that it sits just inside <strong>the</strong>wound pad of your Band-Aid. The o<strong>the</strong>r end willprotrude past <strong>the</strong> end of your Band-Aid. It shouldresemble Figure 8-14.Now, remove <strong>the</strong> MEA from <strong>the</strong> bag carefullyusing cotton gloves (see Figure 8-15).You need to trim <strong>the</strong> MEA so that it is slightlybigger than <strong>the</strong> wound pad of your Band-Aid, butso that <strong>the</strong>re is still a generous border ofBand-Aid sticky to hold <strong>the</strong> assembly toge<strong>the</strong>r.The MEA must overlap <strong>the</strong> wound pad(see Figure 8-16).102
Figure 8-13 When removing <strong>the</strong> cover of <strong>the</strong>Band-Aid, do not touch <strong>the</strong> wound pad.The next shot (Figure 8-17) displays <strong>the</strong> MEAchecked <strong>for</strong> size against a Band-Aid. Note that“anode” is marked on <strong>the</strong> MEA—you need tomake a note of on which side “anode” appears <strong>the</strong>correct way round on; make a note of this and puta “+” on <strong>the</strong> Band-Aid facing <strong>the</strong> MEA. You mightwant to use an overhead projector pen to do this.Next, lay <strong>the</strong> MEA on <strong>the</strong> wire mesh (seeFigure 8-18), noting orientation. Ensure that <strong>the</strong>overlap of <strong>the</strong> MEA sticks to <strong>the</strong> border of Band-Aid adhesive—you need to isolate each side of <strong>the</strong>MEA from each o<strong>the</strong>r using <strong>the</strong> Band-Aid adhesiveas a barrier.Figure 8-15Getting <strong>the</strong> MEA out of <strong>the</strong> bag.Now take <strong>the</strong> o<strong>the</strong>r strip of wire mesh that youcut, and lay it up on <strong>the</strong> MEA so that <strong>the</strong> sparelength of gauze protrudes from <strong>the</strong> opposite end.I found at this point that it was a good idea tobend <strong>the</strong> wire gauze back on <strong>the</strong> Band-Aid, correspondingto <strong>the</strong> side of <strong>the</strong> MEA <strong>the</strong> gauze was incontact with. This helped me to remember whichpiece of gauze was what electrode.Now, use a scalpel to remove a 1-cm square of<strong>the</strong> pink bit of Band-Aid from <strong>the</strong> side that is inProject 30: Building a Band-Aid ® <strong>Fuel</strong> <strong>Cell</strong>Figure 8-14Band-Aid.Laying <strong>the</strong> wire mesh on <strong>the</strong> firstFigure 8-16Trimming <strong>the</strong> MEA to size.103
Project 30: Building a Band-Aid ® <strong>Fuel</strong> <strong>Cell</strong>Figure 8-17Checking <strong>the</strong> MEA <strong>for</strong> size.contact with <strong>the</strong> anode side of <strong>the</strong> MEA(see Figures 8-20 and 8-21).Testing <strong>the</strong> Band-Aid fuel cellTo test <strong>the</strong> fuel cell, you will need some 3%methanol solution. Again, you can get this from fuelcell stores, unless you know a bit about chemistry orare friendly with a college lab technician.To fuel <strong>the</strong> cell, you will need to introducemethanol solution to <strong>the</strong> patch of Band-Aid youremoved on one side. The wound patch will act asa reservoir <strong>for</strong> <strong>the</strong> fluid. Keep <strong>the</strong> o<strong>the</strong>r side of <strong>the</strong>Figure 8-18Laying <strong>the</strong> MEA on <strong>the</strong> wire mesh.Figure 8-19 Laying <strong>the</strong> final layer of wire mesh ontop of <strong>the</strong> MEA.fuel cell dry, and oxygen will permeate through <strong>the</strong>breathable Band-Aid.Connect <strong>the</strong> electrodes protruding from ei<strong>the</strong>rend of <strong>the</strong> Band-Aid to a multimeter, but do notexpect big shakes first time round! DMFC fuelcells take time to “break in.”I found that <strong>the</strong> voltage that my cell producedwas improved by applying a little light pressure to<strong>the</strong> area ei<strong>the</strong>r side of <strong>the</strong> methanol top-up point.This is because <strong>the</strong> wire gauze makes better contactwith <strong>the</strong> MEA.Figure 8-20 Using a scalpel to remove a square from<strong>the</strong> top layer of <strong>the</strong> Band-Aid (initial cut).104
Figure 8-21 Using a scalpel to remove a square from<strong>the</strong> top layer of <strong>the</strong> Band-Aid (completing <strong>the</strong> cuts).The future of DMFCsYou’ll see in our Band-Aid fuel cell that we had aseparate anode and cathode—and it’s importantthat <strong>the</strong> methanol only touches <strong>the</strong> anode. Well, acompany caused CMR has developed an innovativeDMFC fuel cell (see Figure 8-24), which takesaway some of <strong>the</strong> complexity of separating anodesand cathodes in a DMFC stack.Figure 8-22The completed Band-Aid fuel cell.Figure 8-23meter.The Band-Aid fuel cell connected to aWeb link to CMR fuel cellswww.cmrfuelcells.com/index.php?option=com_frontpage&Itemid=1The CMR DMFC fuel cell is different, in usingselective catalysts on <strong>the</strong> anode and cathode side.Their DMFC is fed a bubbled solution of air andmethanol solution. However, because <strong>the</strong> methanolwill only react with <strong>the</strong> selective catalyst on <strong>the</strong>anode, and <strong>the</strong> oxygen will only react with <strong>the</strong>selective catalyst on <strong>the</strong> cathode, no physicalseparation is necessary—this is <strong>the</strong> sort of innovationthat is going to reduce <strong>the</strong> complexity of fuel cells,bring down <strong>the</strong>ir price, and help <strong>the</strong>m to reach <strong>the</strong>consumer electronics market more quickly.We can carry out many of <strong>the</strong> same experimentsin <strong>the</strong> PEM fuel cell chapter, using simple DMFCfuel cells which we can connect in a circuit, suchas that shown in Figure 8-25.Project 30: Building a Band-Aid ® <strong>Fuel</strong> <strong>Cell</strong>105
Project 30: Building a Band-Aid ® <strong>Fuel</strong> <strong>Cell</strong>Figure 8-24Figure 8-25CMR’s innovative DMFC fuel cell.DMFC fuel cell suitable <strong>for</strong> experimentation.106
Chapter 9Microbial <strong>Fuel</strong> <strong>Cell</strong>sIn this book, we have looked mainly at fuel cellswhich rely on physical, chemical reactions takingplace. In this chapter, we are going to look at aradically different type of fuel cell, which operatesin a radically different way—<strong>the</strong> microbial fuel cell.The feedstock <strong>for</strong> microbial fuel cells is a“bioconvertible substrate.” This is jargon <strong>for</strong> asubstance that can be converted biologically intoenergy <strong>for</strong> <strong>the</strong> fuel cell. This can comprise a rangeof things—sugar (glucose), or biomass feedstocksspecifically grown <strong>for</strong> <strong>the</strong> purpose, such as algae.Living creatures take food, and metabolize it toprovide <strong>the</strong>m with energy. They are oxidizingenergy rich, which (reading ahead to LEO <strong>the</strong> Liongoes GER) implies that <strong>the</strong>y are electron rich.The process of digestion is a very complex one,involving lots of reactions which are catalyzed byenzymes. This process happens at relatively lowtemperatures. In <strong>the</strong> reference section, <strong>the</strong> paper byBennetto describes this process as “coldcombustion.”History of <strong>the</strong> microbialfuel cellIn 1912, Professor M.C. Potter, at <strong>the</strong> University ofDurham, managed to extract electricity fromE. coli bacteria—this work was duly published in<strong>the</strong> proceedings of <strong>the</strong> Royal Society, but <strong>the</strong>n wasignored. It took until 1931 <strong>for</strong> <strong>the</strong> idea to be revisited.Barnet Cohen took ano<strong>the</strong>r look at <strong>the</strong> idea andmanaged to produce a number of cells, which,when connected toge<strong>the</strong>r, produced a potentialdifference of 35 volts, albeit at a very low current.Where is <strong>the</strong> technologygoing?Bacteria take in food and produce waste products.Some bacteria take a “fuel” such as glucose, anddigest <strong>the</strong> fuel to produce two waste products:carbon dioxide and water, in <strong>the</strong> presence ofoxygen. If you remove <strong>the</strong> oxygen, <strong>the</strong> bacteriatend to produce carbon dioxide and protons andneutrons.Medical science has now progressed to <strong>the</strong>point where it can prolong life, or improve <strong>the</strong>quality of people’s lives by implanting electricaldevices in <strong>the</strong> body to help assist <strong>the</strong> function ofimpaired organs. Pacemakers and cochlear implantsare examples of medical devices that are implanted“subdermally,” that is to say, “below <strong>the</strong> skin.”These are all candidates that could potentially befueled by microbial fuel cells in <strong>the</strong> future.Scientists at Tohoku University have developedfuel cells which will use blood as a fuel. Thispaves <strong>the</strong> way <strong>for</strong> medical implants that can bepowered by <strong>the</strong> patient, negating <strong>the</strong> need <strong>for</strong>future operations to replace batteries.NASA estimate that over <strong>the</strong> duration of ajourney to Mars, taken to be six years, a crew ofsix astronauts could produce up to six tons of solidorganic waste, with a lot of that being humanexcrement. Clearly in <strong>the</strong> depths of space, youcan’t just FedEx it back home to mission control,so what do you do?Well, microbial fuel cells could help to digestthis waste to turn it into useful electricity. Thiselectricity can be used to power <strong>the</strong> mission, and107Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
Project 31: Building Your Own Microbial <strong>Fuel</strong> <strong>Cell</strong>through <strong>the</strong> process of biological digestion, <strong>the</strong>output product is easier to process.However, microbial fuel cells are also starting tofind practical applications in <strong>the</strong> here and now.Fosters, Australian brewers of “<strong>the</strong> amber nectar,”have installed a microbial fuel cell in <strong>the</strong>ir●●●●●●●●●●●●●●●●brewery, which takes <strong>the</strong> waste products from <strong>the</strong>beer-making process—sugars, yeasts, and alcohols—and digests <strong>the</strong>m, producing clean electricity in <strong>the</strong>process. The output is cleaner waste-water, withoutso many of <strong>the</strong> biologically active components—andfree electricity into <strong>the</strong> bargain!Project 31: Building Your Own Microbial <strong>Fuel</strong> <strong>Cell</strong>2 × P-traps (available from a plumber’s merchant orbuilder’s store)Short length of waste pipe (4 in/10 cm) to fit P- trapsPlastic wrapAgar jellySaltCarbon cloth (available from <strong>Fuel</strong> <strong>Cell</strong> StoreP/N: 590642)Copper wireAquarium aerator pumpLength of aquarium tube“Bubbler” blockEpoxy resin adhesiveBung or plug <strong>for</strong> P-trap top pipe or cooking oilScissorsJunior hacksaw (<strong>for</strong> cutting plastic)StovePanThe best way to learn about how microbial fuelcells work is to construct a simple version. Thismakes an ideal science fair project, and is greatbecause it traverses <strong>the</strong> disciplines of biology andphysics.Making <strong>the</strong> MFC chambersFor our microbial fuel cell, we need to create twoseparate distinct chambers, interlinked by a pipecalled a “salt bridge.” There is a wealth of in<strong>for</strong>mationfrom different experimenters (shown in <strong>the</strong>links section), who have constructed MFCs usingfound items, bottles, plastic tubs, pots, etc. to <strong>for</strong>m<strong>the</strong>ir two chambers. This is a perfectly acceptablesolution; however, you may find that you encounterdifficulty when joining <strong>the</strong> salt bridge to <strong>the</strong> sidesof <strong>the</strong> o<strong>the</strong>r tubs—often lots of epoxy and orsilicone is required, and it is hard to get a goodleak-free join.If you’ve got a little bit of money in yourexperimenter’s budget, nip to your local plumber’ssupply outlet, and ask <strong>for</strong> a couple of P-traps—<strong>the</strong>seare <strong>the</strong> gadgets that fit underneath your washroomsink, and prevent nasty smells coming up from <strong>the</strong>drain. These provide an easy method of joining <strong>the</strong>salt bridge to <strong>the</strong>m, as <strong>the</strong>y come with a coupling,with a rubber gasket to ensure tight, leak-freejoins.108
Figure 9-1 Trial assembly of <strong>the</strong> P-traps and saltbridge pipe.To get <strong>the</strong> best out of a P-trap, you will see ifyou open <strong>the</strong>m up that <strong>the</strong>re is a plastic pipeextending into <strong>the</strong> cavity inside <strong>the</strong> trap. To makeas much room as possible <strong>for</strong> your experiment,take a multitool such as a Dremel, and remove thisplastic protrusion, giving you an empty chamber towork with.You can see in Figure 9-1 what a neat solution apair of P-traps and short length of waste pipe make<strong>for</strong> constructing MFCs.Making <strong>the</strong> salt bridgeOur salt bridge separates <strong>the</strong> reduction and oxidizationsides of our microbial fuel cell, whileconnecting <strong>the</strong>m electrochemically. The salt bridgewill allow a flow of ions between <strong>the</strong> two chambersof our MFC.It consists of a simple tube, filled with a mixtureof salt and agar <strong>for</strong> gelification. If you’re wonderingwhere to get agar from, it is sometimes used as avegetarian substitute <strong>for</strong> gelatin, or you might beusing it in <strong>the</strong> science lab to grow cultures on.To make <strong>the</strong> salt bridge, you’ll need to take <strong>the</strong>short length of pipe, and wrap one end firmly withseveral layers of plastic wrap to seal it. Ensure thatyou make a good seal, and use several layers of <strong>the</strong>wrap pulled taught over <strong>the</strong> end. You could evenrun a bit of tape around as well to secure. Place <strong>the</strong>tube sealed end down.Now, put <strong>the</strong> pan of water on <strong>the</strong> stove. You aregoing to need about 125 ml of agar solution to fillyour salt bridge. However, <strong>for</strong> practicality you mayneed to make more than this in order to heat evenlyin your pan. As a ready reckoner, <strong>for</strong> every liter ofwater, you’re going to need about 100 g of agar.Add <strong>the</strong> agar once <strong>the</strong> water is boiling, and <strong>the</strong>nthrow in some salt.When you’re done, and be<strong>for</strong>e <strong>the</strong> solution startsto gelify and set, pour <strong>the</strong> mixture into <strong>the</strong> 4 in.100 mm length of tube you just covered withplastic wrap, and allow it to solidify and set.When you have allowed <strong>the</strong> jelly to set completely,loosen off <strong>the</strong> clamps on ei<strong>the</strong>r end of <strong>the</strong> P-traps,squeeze <strong>the</strong> ends of <strong>the</strong> pipe into <strong>the</strong> fixing, andtighten <strong>the</strong> clamps up. The rubber gasket trappedbetween <strong>the</strong> big nut and <strong>the</strong> P-trap will ensurea good seal with no leaks.Figure 9-2Aquarium aerator “air brick.”Project 31: Building Your Own Microbial <strong>Fuel</strong> <strong>Cell</strong>109
Project 31: Building Your Own Microbial <strong>Fuel</strong> <strong>Cell</strong>Making <strong>the</strong> electrodesTake two sheets of carbon cloth, and fix a piece ofwire to <strong>the</strong>m. An epoxy resin glue is good <strong>for</strong> this.You want to ensure that <strong>the</strong>re is conductor tocarbon cloth contact, and that <strong>the</strong> glue doesn’tinterfere with this interface. The glue is appliedover <strong>the</strong> joint between <strong>the</strong> carbon cloth and wire,not between it.Test <strong>the</strong> connection between <strong>the</strong> wire andelectrode using a multimeter set to <strong>the</strong> resistancesetting. The reading should be very low.Obtaining <strong>the</strong> bacteria <strong>for</strong>your fuel cellYou are going to need to find some bacteria <strong>for</strong>your fuel cell. You can experiment with differentcultures of bacteria, but it is essential that whenyou are collecting <strong>the</strong>m, you preserve your ownhealth by wearing gloves. You could try collectingsediment from a river.We are going to try to exclude oxygen from ouranode, and in our cathode, we are going to try andcreate an oxygen-rich environment, using an aquariumaerator—a small pump that blows bubbles intoan aquarium to keep <strong>the</strong> little fishies happy!You are going to need to exclude oxygen from<strong>the</strong> anode chamber. There are a couple of ways ofdoing this. You can get some sort of bung or cap,or ano<strong>the</strong>r alternative is to float some oil on top of<strong>the</strong> bioconvertable mixture, which will preventoxygen from reaching it. Water and oil are notmiscible, and <strong>the</strong> oil will just float on top of <strong>the</strong>water-based solution.The pump <strong>for</strong>ces air down a small piece ofaquarium tube; however, we also need an additionaldevice on <strong>the</strong> end of <strong>the</strong> tube called an “air brick.”The air brick (Figure 9-2) is a small piece ofporous ceramic that takes <strong>the</strong> feed of air comingfrom <strong>the</strong> aerator, and breaks it up into a plethora oflittle bubbles. The effect of an aerator brick canclearly be seen by looking at <strong>the</strong> pipe submergedFigure 9-3With and without aerator bricks.in a glass (see Figure 9-3). When <strong>the</strong> plain pipehas air blown through it, <strong>the</strong>re are a small numberof large bubbles, however, when <strong>the</strong> aerator brickis added, <strong>the</strong>re are a large number of small bubbles.This is important, because it is <strong>the</strong> surface areaof <strong>the</strong> bubbles in contact with <strong>the</strong> water that we aretrying to maximize to increase <strong>the</strong> rate of <strong>the</strong>reaction.Powering up your MFCRemember that you marked one chamber “A” <strong>for</strong>anode and ano<strong>the</strong>r “C” <strong>for</strong> cathode. Well, this isimportant now as you are going to need to add <strong>the</strong>right mixtures to <strong>the</strong> right chamber.To <strong>the</strong> anode:You are going to add <strong>the</strong> inoculum—this is ourbacterial mix.To <strong>the</strong> cathode:We are going to add some electrolyte—saltwater solution.Connect a multimeter to <strong>the</strong> terminals of yourMFC—a really easy way to do this is to soldersome banana plugs onto <strong>the</strong> ends of your multimeterleads, so you can connect <strong>the</strong>m directly to a meter.Looking a little closer, we can refer to Figure 9-5<strong>for</strong> a diagram of what is going on. Figure 9-5 is asimplification of our P-traps and assembly, and itschematically represents <strong>the</strong> MFC. In our anode110
Figure 9-4chamber, we have our bacterium, isolated from airand our anode electrode.Inside, <strong>the</strong> bacteria are digesting food and, in <strong>the</strong>process, giving up electrons to <strong>the</strong> anode terminal.The anode is “gaining” electrodes; <strong>the</strong>re<strong>for</strong>e, aprocess of reduction is happening at this electrode.The bacterium that we use in this fuel cell(Figure 9-6) must be a mediatorless bacterium, aswe did not add any additional chemicals to “mediate”<strong>the</strong> transfer of electrons from <strong>the</strong> bacterium to <strong>the</strong>electrode.Remember LEO <strong>the</strong> Lion goes GER? Loss ofElectrons is Oxidation, and Gain Equals Reduction.So by losing electrons to <strong>the</strong> electrode, <strong>the</strong> processof oxidation is occurring. The electrons <strong>the</strong>n make<strong>the</strong>ir way around <strong>the</strong> circuit to <strong>the</strong> cathode.Figure 9-5The completed microbial fuel cell.Diagram of <strong>the</strong> microbial fuel cell.Figure 9-6Geobacteraceae bacterium.Here, oxygen is being bubbled through anelectrolyte solution.At <strong>the</strong> o<strong>the</strong>r electrode, we are bubbling oxygenthrough an electrolyte. The cathode electrode islosing electrons, <strong>the</strong>re<strong>for</strong>e “loss equals oxidation.”Figure 9-7 LEO <strong>the</strong> Lion goes GER—a great way toremember “Loss of Electrons Equals Oxidation” and“Gain Equals Reduction”Project 31: Building Your Own Microbial <strong>Fuel</strong> <strong>Cell</strong>111
Project 31: Building Your Own Microbial <strong>Fuel</strong> <strong>Cell</strong>Figure 9-8So we can see how <strong>the</strong> reduction–oxidation cycleis complete, with one electrode reducing, while <strong>the</strong>o<strong>the</strong>r is oxidizing. The salt bridge provides ameans <strong>for</strong> ions to flow between <strong>the</strong> two chamberswhile isolating <strong>the</strong> two solutions.Mediatorless microbes transfer electrons directlyto <strong>the</strong> electrode, without <strong>the</strong> need <strong>for</strong> an electronshuttle.O<strong>the</strong>r students’ fuel cellsThere are a plethora of good microbial fuel cellprojects on <strong>the</strong> Internet. To all intents and purposes,Figure 9-9The reduction–oxidation cycle.Mediatorless transfer.microbial fuel cells make <strong>for</strong> very successfulscience fair projects, and being so new, <strong>the</strong>re isexciting research that can be done by amateurs.I urge you to take a look at Abbie Groff’s awardwinningmicrobial fuel cell research. When I beganreading around this subject, Abbie Groff’s workshaped a lot of my direction with this project:www.geocities.com/abigail_groff/Here are some of Abbie’s press cuttings, resultingfrom her <strong>for</strong>ays into <strong>the</strong> world of microbial fuelcells—discover something new and this couldbe you!www.engr.psu.edu/ce/enve/mfc-Logan_files/PDFs/Student%20MFC%20papers/Abbie%20Groff4.<strong>pdf</strong>Sikander Porter-Gill’s project also makes <strong>for</strong>interesting reading:www.engr.psu.edu/ce/enve/mfc-Logan_files/PDFs/Student%20MFC%20papers/MFC-Sikandar.<strong>pdf</strong>Erik A. Zielke also has some interesting work:www.engr.psu.edu/ce/enve/mfc-Logan_files/PDFs/Student%20MFC%20papers/Engr_499_final_zielke.<strong>pdf</strong>Penn State University has a fantastic microbialfuel cells resource page (www.engr.psu.edu/ce/enve/mfc-Logan_files/mfc-Logan.html), and if youbuild an MFC like <strong>the</strong> one featured here, <strong>the</strong>y wantto hear from you! If you get a successful MFCproject, send some details to blogan@psu.eduMicrobial fuel cells—withmediatorMediatorless microbes transfer electrons directly to<strong>the</strong> electrode, without <strong>the</strong> need <strong>for</strong> an electronshuttle. The MFC we have created is a mediatorlessmicrobial fuel cell because <strong>the</strong>re isn’t an additionalchemical to “mediate” between microbes andelectrodes (Figure 9-9).112
Figure 9-10Mediator MFC.There is ano<strong>the</strong>r type of microbial fuel cell—<strong>the</strong>mediator MFC, where an additional chemical actsto shuttle <strong>the</strong> electrons from <strong>the</strong> microbes to <strong>the</strong>MFC. This is illustrated in Figure 9-10.Reading University’s National Centre <strong>for</strong>Biotechnology Research has produced a verycompact microbial fuel cell kit. The kit is based on<strong>the</strong> principles discussed in Peter Bennetto’s paper(1990).Look at Figure 9-10—this is what happens insidea fuel cell which requires a mediator. In <strong>the</strong> ReadingUniversity kit, yeast is used as <strong>the</strong> bacterium, andmethylene blue is used as <strong>the</strong> mediator, shuttlingelectrons between <strong>the</strong> bacteria and <strong>the</strong> electrodes.Reading University has published in<strong>for</strong>mationabout <strong>the</strong>ir microbial fuel cell in <strong>the</strong> online journal,Bioscience-Explained. You can download thisin<strong>for</strong>mation from www.bioscience-explained.org/EN1.1/<strong>pdf</strong>/FulcelEN.<strong>pdf</strong>Fur<strong>the</strong>r Investigation●●H.P. Bennetto (1990) Elecricity generationfrom micro-organisms: www.ncbe.reading.ac.uk/NCBE/MATERIALS/MICROBIOLOGY/PDF/bennetto.<strong>pdf</strong>H. Liu and B.E. Logan (2004) Electricitygeneration using an air-cathode single chambermicrobial fuel cell in <strong>the</strong> presence and absenceof a proton exchange membrane: www.engr.psu.edu/ce/enve/publications/2004-Liu&Logan-ES&T.<strong>pdf</strong>Project 31: Building Your Own Microbial <strong>Fuel</strong> <strong>Cell</strong>113
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Chapter 10High Temperature <strong>Fuel</strong> <strong>Cell</strong>sIn this book so far, we have chosen experimentswhich can be per<strong>for</strong>med with relative safety athome. The type of fuel cells that we have looked atcan be classed as “low-temperature fuel cells”;however, <strong>the</strong>re is ano<strong>the</strong>r class of fuel cellsthat is suited towards different applications—“high-temperature fuel cells.”Take a look at Table 10-1. Here we can see <strong>the</strong>five main classes of fuel cells. Note that in thistable, we group DMFCs with PEM fuel cells, asboth operate on a membrane principle.Un<strong>for</strong>tunately, because <strong>the</strong>y operate at hightemperature, it is not practical to construct or experimentwith <strong>the</strong>m, but we do at least owe <strong>the</strong>m <strong>the</strong>duty to discuss <strong>the</strong>m, so that your knowledge offuel cell technology is complete.High-temperature fuel cells can be used instacks, like <strong>the</strong> stacks we saw in <strong>the</strong> PEM fuel cell.In Figure 10-1, we see a solid oxide fuel cell stack—<strong>the</strong> stack is made up of a sandwich of platters,a separator plate, followed by an anode plate, anelectrolyte plate and a cathode plate. The sequence<strong>the</strong>n repeats. <strong>Fuel</strong> is supplied through a centralpipe, with additional air being supplied by <strong>the</strong> twopipes ei<strong>the</strong>r side of <strong>the</strong> center.Of course, because high-temperature fuel cellsrequire additional support equipment, <strong>the</strong> inventoryof components required to support a hightemperaturefuel cell extends beyond <strong>the</strong> stackitself. We can see in Figure 10-2 a small 1-kWsolid oxide fuel cell stack (<strong>the</strong> same one as we sawin Figure 10-1), in <strong>the</strong> lab with its associate supportequipment.Table 10-1Comparison of fuel cell technologies.MoltenPhosphonic acid carbonate Solid oxidePEM fuel cell Alkaline fuel cell fuel cell fuel cell fuel cellElectrolyte H + ions in a OH − ions in a KOH H + ions in a H 3PO 4CO − ions in 3 O− ions in apolymer solution solution a molten ceramicmembrane carbonate matrix wi<strong>the</strong>utectic free oxide ions— —Ability to re<strong>for</strong>mfuels internally?Oxidant: air — Purified — — —Oxidant:O 2— —Ideal operational 65–85° C 90–260° C 190–210° C 650–700° C 700–1000° Ctemperature 150–180° F 190–500° F 370–410° F 1200–1300° F 1350–1850° FSystem efficiency 25%–35% 32%–40% 35%–45% 40%–50% 45%–55%contaminated by: CO, S, NH 3CO, CO 2S, NH 3CO, S S S115Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
High Temperature <strong>Fuel</strong> <strong>Cell</strong>sFigure 10-1 Solid oxide fuel cell stack.Image courtesy Technology Management Inc.Also, because of <strong>the</strong> high temperatures associatedwith high-temperature fuel cells (it’s all in <strong>the</strong>name!), <strong>the</strong>re is a certain amount of supportequipment that means that <strong>for</strong> very small amountsof power, high-temperature fuel cells just aren’teconomical. To give you an example, hightemperaturefuel cells don’t get a lot smaller than<strong>the</strong> device shown in Figure 10-3, a 1-kW solidoxide fuel cell stack with support circuitry.We are going to take a look at three hightemperaturefuel cell types, and briefly cover someaspects of <strong>the</strong> technology.Phosphoric acid fuel cellsIn a phosphoric acid fuel cell (PAFC), <strong>the</strong> electrolyteis retained by a matrix of silicon carbide, whichkeeps <strong>the</strong> highly concentrated phosphoric acidin place.Figure 10-2 Solid oxide fuel cell stack and supportequipment in <strong>the</strong> lab. Image courtesy TechnologyManagement Inc.Figure 10-31-kW solid oxide fuel cell stack.116
Figure 10-4Phosphoric acid fuel cell chemistry.The reason <strong>for</strong> <strong>the</strong> high temperatures of phosphoricacid fuel cells is that at lower temperatures,phosphoric acid proves to be a poor conductor ofions. Fur<strong>the</strong>rmore, at lower temperatures, <strong>the</strong> fuelcell is more readily poisoned by carbon monoxide.Also, phosphoric acid solidifies at 40∞ C or104∞ F, which means that cold-starting of PAFCscan be ra<strong>the</strong>r tricky. To eliminate this operationcomplexity, PAFCs are usually used in applications,e.g., in buildings, where <strong>the</strong>y can be installedand operate continuously without <strong>the</strong> need <strong>for</strong>cold-starting.In addition to building integrated PAFCs, promisehas also been shown in utility-scale applicationswhere PAFCs can be used as mini power stations,producing supplemental power <strong>for</strong> <strong>the</strong> grid.Additional heat produced from <strong>the</strong> PAFCoperation must be removed. This can be done byincorporating coolant channels into <strong>the</strong> coolantstack—not unlike <strong>the</strong> coolant channels that runthrough <strong>the</strong> internal combustion engine in your car.Ei<strong>the</strong>r liquid or gas can be passed through <strong>the</strong>sechannels to cool <strong>the</strong> PAFC.Phosphoric acid fuel cells are one of <strong>the</strong> mostmature fuel cell technologies. They are very wellunderstood, and used in commercial operations ata number of sites.If you are still interested in phosphoric acid fuelcells, and want to find out more, you could checkout some of <strong>the</strong>se top Web links as a springboardto fur<strong>the</strong>r in<strong>for</strong>mation:www.fctec.com/fctec_types_pafc.aspwww.nfcrc.uci.edu/EnergyTutorial/pafc.htmlwww.fossil.energy.gov/programs/powersystems/fuelcells/fuelscells_phosacid.htmlamericanhistory.si.edu/fuelcells/phos/pafcmain.htmMolten carbonatefuel cellsMolten carbonate fuel cells also operate at veryhigh temperatures. Their electrolyte is a moltencarbonate salt mixture, suspended on a ceramicmatrix. In current MCFC fuel cells, two mixturesof carbonates are currently used: lithium carbonateand potassium carbonate, or lithium carbonate andsodium carbonate.As a result of <strong>the</strong> high temperatures that MCFCsoperate at, it is not necessary to use platinum as acatalyst; instead, o<strong>the</strong>r cheaper metals, such asnonprecious metals, can be used.Figure 10-5Molten carbonate fuel cell chemistry.High Temperature <strong>Fuel</strong> <strong>Cell</strong>s117
High Temperature <strong>Fuel</strong> <strong>Cell</strong>sMolten carbonate fuel cells can reach very highefficiencies—even higher when waste heat producedby <strong>the</strong> fuel cell is captured. This heat can be used<strong>for</strong> o<strong>the</strong>r processes or heating, which means moreuseful energy is delivered to <strong>the</strong> application andless is wasted.O<strong>the</strong>r fuels can also be internally re<strong>for</strong>med,which presents flexibility in <strong>the</strong> range of fuels thatcan be used.As a result of <strong>the</strong> high temperatures, MCFCs areresistant to poisoning by carbon monoxide andcarbon dioxide. However, sulfur in fuels stillpresents a problem and must be scrubbed from <strong>the</strong>fuel be<strong>for</strong>e it is supplied to <strong>the</strong> MCFC.As a result of <strong>the</strong> high temperatures required,<strong>the</strong>se cells take some time to start up, and requiresome <strong>the</strong>rmal shielding or insulation to be added to<strong>the</strong> cell to ensure that it operates efficiently.One of <strong>the</strong> problems that needs to be surmountedat <strong>the</strong> moment is <strong>the</strong> durability of MCFCs: some of<strong>the</strong> materials that <strong>the</strong>y use in <strong>the</strong> electrolyte are highlycorrosive, and as a result of this, and <strong>the</strong> fact that<strong>the</strong>se cells are operating at a very high temperature,premature component failure can result.If you want to learn more about molten carbonatefuel cells, <strong>the</strong> following are some super links tosites with high-quality content that you might liketo check out:www.fctec.com/fctec_types_mcfc.aspwww.fuelcellmarkets.com/fuel_cell_markets/molten _carbonate_fuel_cells_mcfc/www.fossil.energy.gov/programs/powersystems/fuelcells/fuelcells_moltencarb.htmlen.wikipedia.org/wiki/Moltencarbonate_fuel_celldodfuelcell.cecer.army.mil/molten.htmlamericanhistory.si.edu/fuelcells/mc/mcfcmain.htmwww.nfcrc.uci.edu/EnergyTutorial/mcfc.htmlSolid oxide fuel cellsAs a result of <strong>the</strong> very high temperatures that <strong>the</strong>yoperate at, solid oxide fuel cells are primarilysuited towards stationary applications. The gasesthat are produced by SOFCs are so hot that, on<strong>the</strong>ir own, <strong>the</strong>y can be used to power a gas turbine.Fur<strong>the</strong>r low-grade heat can <strong>the</strong>n be recovered after<strong>the</strong> turbine <strong>for</strong> heating purposes.SOFCs must run at very high temperatures, as<strong>the</strong> materials <strong>the</strong>y are made from only becomeelectronically and ionically active at very hightemperatures.Like <strong>the</strong> MCFCs, because of <strong>the</strong> hightemperatures required, <strong>the</strong>se cells take some timeto start up, and require some <strong>the</strong>rmal shielding orinsulation to be added to <strong>the</strong> cell to ensure that itoperates efficiently.As a result of <strong>the</strong> very high temperaturesthat SOFCs operate at, poisoning of <strong>the</strong> fuelcell by carbon monoxide is not an issue. However,sulfur must be scrubbed from <strong>the</strong> fuel supply asSOFCs are still susceptible to sulfur poisoning.Figure 10-6Solid oxide fuel cell chemistry.118
As a result of <strong>the</strong> solid oxide fuel cell’s toleranceto poisoning, and its ability to re<strong>for</strong>m fuels within<strong>the</strong> fuel cell, it is suited to a wide range ofdifferent hydrogen-containing fuel sources.Shared with <strong>the</strong> molten carbonate fuel cell, oneof <strong>the</strong> advantages of <strong>the</strong> solid oxide fuel cell is thatit can re<strong>for</strong>m fuels in situ, which means that wecan supply it with a supply of natural gas directfrom <strong>the</strong> gas pipeline, and it will re<strong>for</strong>m <strong>the</strong> gasitself, with no need <strong>for</strong> an intermediate stage.This provides additional flexibility <strong>for</strong> someapplications.There is a wealth of material about solid oxidefuel cells on <strong>the</strong> Web. Here are some links topages with high-quality in<strong>for</strong>mation:www.svec.uh.edu/SOFC.htmlwww.fossil.energy.gov/programs/powersystems/fuelcells/fuelcells_solidoxide.htmlwww.iit.edu/~smart/garrear/fuelcells.htmwww.azom.com/details.asp?ArticleID=919High Temperature <strong>Fuel</strong> <strong>Cell</strong>s119
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Chapter 11Scratch-Built <strong>Fuel</strong> <strong>Cell</strong>sIf you have got this far in <strong>the</strong> book, <strong>the</strong> chances areyou now have <strong>the</strong> armory of knowledge required tostart thinking about building your own fuel cellsfrom scratch. In this chapter, we are going to lookat some of <strong>the</strong> skills required to build membranefuel cells.If you haven’t already had <strong>the</strong> chance, take apeek at <strong>the</strong> chapter on direct methanol fuel cells(Chapter 8), and <strong>the</strong> project “Build Your OwnBand-Aid ® <strong>Fuel</strong> <strong>Cell</strong>.” It was in devizing thisproject that I began to realize how simple fuel cellsreally are—simply a sandwich of components in<strong>the</strong> right order, made from <strong>the</strong> right materials.Although <strong>the</strong> construction is fairly simple, <strong>the</strong>skill of manufacturing fuel cells is to ensure thatall components are optimized—this is <strong>the</strong> challengeof manufacturers, who every day are working onways to make fuel cells smaller and cheaper.In this chapter, we are going to briefly exploresome of <strong>the</strong> tools, techniques, and materials ofscratch-built fuel cell fabrication. The ease ofbuilding your own fuel cells from scratch is thatmany of <strong>the</strong> components are available as premadeoff-<strong>the</strong>-shelf items, if you don’t want to totallystart from scratch, but as you gain skills, experience,and confidence, you can begin to build more componentsand vary <strong>the</strong> balance between off-<strong>the</strong>-shelfand homemade—to <strong>the</strong> point where you can <strong>the</strong>nstart from raw materials and turn out commercialgradefuel cells.We are going to start at <strong>the</strong> ends of our fuel celland work our way in.It is possible to make fuel cells in a variety ofshapes and sizes, however, <strong>the</strong>re are somecomponents available which follow a standardsizing, and have holes and membrane areas incommon places. Until you get confidence withbuilding fuel cells, it’s probably a good idea tostart from one of <strong>the</strong>se template layouts, usingstock components to begin with, and <strong>the</strong>n fabricatingnew components as you gain in confidence. Thishas <strong>the</strong> benefit of you being able to take dimensionsfrom <strong>the</strong> old components as patterns, modifyingparameters one by one, and seeing what effectit has on <strong>the</strong> fuel cell’s per<strong>for</strong>mance.Scratch-built fuel cellcomponentsEnd-platesThe job of <strong>the</strong> end-plates in a fuel cell is to berigid enough to firmly support <strong>the</strong> internal componentsof <strong>the</strong> fuel cell, to provide a fixing <strong>for</strong> <strong>the</strong>hydrogen and oxygen supply connections, and toprovide a surface <strong>for</strong> <strong>the</strong> fixings that secure <strong>the</strong>fuel cell sandwich toge<strong>the</strong>r to screw down on.A wide variety of materials are suitable <strong>for</strong>end-plate construction. You might want to considerusing an electrically insulating material <strong>for</strong> <strong>the</strong>end-plate, to ensure that it doesn’t provide a path<strong>for</strong> stray electrons to short on. Fiberglass sheet isan ideal material to produce end-plates from, as itis strong, robust, and can be easily worked. Someplastics are suitable <strong>for</strong> end-plate construction,however, you must ensure that <strong>the</strong>y are sufficientlyrigid, as a material with too much bend will notprovide <strong>the</strong> mechanical support <strong>the</strong> MEA needsthrough <strong>the</strong> center of <strong>the</strong> stack.121Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
Scratch-Built <strong>Fuel</strong> <strong>Cell</strong>sFigure 11-1fabrication.Fiberglass sheet suitable <strong>for</strong> end-plateYou want to ensure that <strong>the</strong> material does notbend significantly, as you want pressure to bespread from <strong>the</strong> screws or clamps at <strong>the</strong> outside of<strong>the</strong> cell, to <strong>the</strong> center of <strong>the</strong> cell, where <strong>the</strong> endplatesmaintain <strong>the</strong> electrodes’ contact with<strong>the</strong> MEA.If producing your end-plates sounds like toomuch trouble, <strong>Fuel</strong> <strong>Cell</strong> Store sell a set of endplateswith mounting components <strong>for</strong> a 10 cm ×10 cm fuel cell stack–Part No: 590300.To produce an end-plate, start with a fiberglasssheet, such as that shown in Figure 11-1. The <strong>Fuel</strong><strong>Cell</strong> Store sells a garolite (fiberglass and epoxy)sheet that is suitable <strong>for</strong> end-plate construction.Their stock number is 72043001.The end-plate needs to have holes <strong>for</strong> nuts andbolts to be inserted through, which are <strong>the</strong>n tightenedto provide pressure on <strong>the</strong> stack. Ano<strong>the</strong>r alternativeis to use a threaded rod with nuts on ei<strong>the</strong>r end.The end-plate also needs to have a suitablefixing <strong>for</strong> hydrogen and oxygen supplies andreturn feeds. A simpler construction of fuel cellwill use hydrogen and air, in which case pipes <strong>for</strong>oxygen do not need to be provided. If you thinkback to <strong>the</strong> fuel cells you have been using in <strong>the</strong>chapter on PEM fuel cells, <strong>the</strong>y all have <strong>the</strong>irintegral fixings molded as part of <strong>the</strong> plastic endplate.However, if you are working from a fiberglasssheet, you will need to find a way to affix aconnection to <strong>the</strong> plate.You will see that <strong>the</strong> end-plate in Figure 11-2has four holes at <strong>the</strong> corners <strong>for</strong> fixings, and twoconnections <strong>for</strong> hydrogen and return gas at <strong>the</strong> topin <strong>the</strong> center of <strong>the</strong> plate.The positioning of your holes and gas feeds candiffer slightly—this is just an example. As endplatesare one of <strong>the</strong> easier parts of <strong>the</strong> fuel cellstack to manufacture, it is probably best to design<strong>the</strong>m around any available flow fields, ra<strong>the</strong>r than<strong>the</strong> o<strong>the</strong>r way around.If you haven’t got <strong>the</strong> facilities, or you haven’tgot <strong>the</strong> patience to sit and make your own endplates,<strong>the</strong> <strong>Fuel</strong> <strong>Cell</strong> Store sells some readymanufacturedend-plates, with holes in <strong>the</strong> rightFigure 11-2An example end-plate.122
Figure 11-3Gas connection.places <strong>for</strong> <strong>the</strong>ir ready-made flow fields. Theend-plate kit comes with barbs <strong>for</strong> gas alreadyfitted, and a set of eight insulated fixings to hold<strong>the</strong> fuel cell toge<strong>the</strong>r. The stock number is 590300.There are a number of different fixings <strong>for</strong> gasconnections. It is important that you can make agood leak-proof joint between <strong>the</strong> “barb”—<strong>the</strong> bitthat sticks out to interface with <strong>the</strong> pipe, and <strong>the</strong>end-plate. Some barbs will simply screw into <strong>the</strong>end-plate, while o<strong>the</strong>rs may require some epoxy oro<strong>the</strong>r <strong>for</strong>m of adhesive.The hydrogen distribution design remains similar<strong>for</strong> both types of fuel cell—you take <strong>the</strong> hydrogenfrom a common point which feeds from <strong>the</strong> barbedtube connector at <strong>the</strong> end of <strong>the</strong> fuel cell, and usinga flow field channeled in <strong>the</strong> graphite, you providea passage <strong>for</strong> <strong>the</strong> hydrogen to spread over <strong>the</strong> surfaceof <strong>the</strong> MEA. You can see an example hydrogenflow field plate in Figure 11-4.Notice how <strong>the</strong>re are four holes on <strong>the</strong> outside of<strong>the</strong> plate at each corner: <strong>the</strong>se are to provide <strong>the</strong>manner of fixing <strong>the</strong> fuel cell toge<strong>the</strong>r, with boltspassing through all <strong>the</strong> plates and <strong>the</strong> entire assembly.Meanwhile, you will notice two small holesat <strong>the</strong> top of <strong>the</strong> plate—<strong>the</strong>se are to connect <strong>the</strong>serpentine pattern, which we can see below, to twocommon channels which provide connection to <strong>the</strong>hydrogen feed.If your fuel cell is to run on hydrogen and oxygen,you will want to take a similar pattern to Figure11-4, but with <strong>the</strong> holes positioned in a differentplace <strong>for</strong> an oxygen feed. This will <strong>the</strong>n take asupply of oxygen, attached to a barb fixed in <strong>the</strong>opposite end-plate in a different position, anddistribute <strong>the</strong> oxygen over <strong>the</strong> opposite side of <strong>the</strong>MEA to <strong>the</strong> hydrogen.Scratch-Built <strong>Fuel</strong> <strong>Cell</strong>sGraphite flow fieldsThe next component inbetween your end-platesis <strong>the</strong> flow fields. It is <strong>the</strong> flow fields that take<strong>the</strong> gases from <strong>the</strong> common feeds machinedthroughout your fuel cell stack, and distribute<strong>the</strong>m evenly over <strong>the</strong> MEA. In addition to <strong>the</strong>mechanical function of helping distribute <strong>the</strong> gas,and providing physical support to <strong>the</strong> MEA, <strong>the</strong>yalso have <strong>the</strong> electrical function of providing acontact to <strong>the</strong> gas diffusion membrane to allow <strong>the</strong>power to flow!You need to make a decision as to whe<strong>the</strong>r yourfuel cell is to run on hydrogen and air, or hydrogenand oxygen.Figure 11-4Hydrogen flow field plate.123
Scratch-Built <strong>Fuel</strong> <strong>Cell</strong>sFlow field plate suitable <strong>for</strong> a hydrogen-Figure 11-5air fuel cell.If your fuel cell is to run on hydrogen and air,you will use straight plates on <strong>the</strong> “oxygen side” toallow air from outside <strong>the</strong> fuel cell to flow along<strong>the</strong> straight channels to make contact with <strong>the</strong>MEA. There are no tubes, <strong>the</strong> air enters <strong>the</strong> fuelcell at <strong>the</strong> bottom and leaves at <strong>the</strong> top. Naturalconvection currents created by <strong>the</strong> generation ofany excess heat can help to increase <strong>the</strong> circulationof air. A straight plate is shown in Figure 11-5.Additionally, you could experiment with <strong>for</strong>cedventilation, attaching a fan to one side of <strong>the</strong> stackto increase <strong>the</strong> throughput of air.If you want some ideas <strong>for</strong> different patterns <strong>for</strong>your flow fields, take a peek back at Figures 7-10<strong>for</strong> straight, Figure 7-11 <strong>for</strong> interdigitated,Figure 7-12 <strong>for</strong> serpentine, and Figure 7-13 <strong>for</strong>spiral—<strong>for</strong> inspiration.You can buy ready-machined flow field plateswhich take <strong>the</strong> hassle out of making your own.They are available from <strong>Fuel</strong> <strong>Cell</strong> Store—this Weblink will show you all <strong>the</strong>ir ready-made plates:www.fuelcellstore. com/cgi-bin/tornado/view=NavPage/cat=58.If you are building a single-cell fuel cell, youwill require one anode plate, with channels on oneside, and one cathode plate, with channels on oneside. However, if you are making a fuel cell stack,you will need to employ “bipolar plates.” A bipolarplate has <strong>the</strong> channels cut out on one side <strong>for</strong>hydrogen and <strong>the</strong> channels cut out on <strong>the</strong> o<strong>the</strong>rside <strong>for</strong> oxygen (or air). It acts as an electricalconductor, allowing power to be transmitted down<strong>the</strong> length of <strong>the</strong> fuel cell stack, while also providinga method to keep <strong>the</strong> hydrogen and oxygen gasesseparate. The bipolar plates fit in between <strong>the</strong> endanode plate and <strong>the</strong> end cathode plate.If you are looking at producing your own flowfield plates, you will need to start with a plaincarbon block, cut to <strong>the</strong> dimensions of your fuelcell. In terms of thickness, you need to allowenough material to be moved when you are milling<strong>the</strong> channels <strong>for</strong> <strong>the</strong> gas to flow through. If youlook at Figure 11-6, you will see a plain carbonplate suitable <strong>for</strong> <strong>the</strong> purpose.You can buy blanks ready <strong>for</strong> your own machiningand treatment, or you can cut your own from ablock of graphite. Be<strong>for</strong>e cutting slices, square(or rectangle) from your raw block of graphite,ensure that you check <strong>the</strong> sides <strong>for</strong> parallelism.Graphite is a lovely material to work with—it’sreally nice and soft to mill into, so you don’t needespecially flash equipment to cut <strong>the</strong> flow channelsinto it. Consider when working with your graphitethat a little bit of water will aid <strong>the</strong> cutting processand keep <strong>the</strong> workpiece cool. Graphite is a goodlubricant, so you won’t need cutting fluid—justsomething to keep <strong>the</strong> dust down and remove<strong>the</strong> heat.When drilling or milling <strong>the</strong> graphite plate, setyour drill or mill to <strong>the</strong> slowest speed possible.124
Figure 11-6 Plain graphite plate suitable <strong>for</strong> flow fieldconstruction.You do not need to work at high speed whenmachining graphite.When considering tools, you have a number ofoptions. Probably <strong>the</strong> simplest is to use one of <strong>the</strong>handheld multifunction tools, such as <strong>the</strong> DremelMulti, which offer a wide range of heads and attachments<strong>for</strong> different purposes. This will enable youto manually route out a groove in <strong>the</strong> carbon—youcan <strong>the</strong>n drill your holes using a small bench-toppillar drill.If you’ve got access to a more sophisticated workshop,you could consider using a milling machine,to enable you to make accurate straight lines <strong>for</strong>your serpentine pattern. For those of you who arenow lost, with a milling machine, you can clamp<strong>the</strong> workpiece on a flat bed, and you have a numberof controls—if you think of <strong>the</strong> old Etch A Sketchmachines, you have two knobs: an X and a Y, and<strong>the</strong>y allow you to draw lines with <strong>the</strong> cutting tool.The difference is that you can also start and stop<strong>the</strong> line by raising <strong>the</strong> milling bit, Z.Now, this is all well and good <strong>for</strong> single flowfields; however, if you are building a fuel cellstack, <strong>the</strong> chances are you will quickly find thisbecomes a tiresome exercise—<strong>the</strong>re’s also adistinct possibility that if making <strong>the</strong> flow-fieldsmanually, <strong>the</strong>re will be some operator error <strong>the</strong>n,and <strong>the</strong>y might not all line up correctly.The pièce de resistance of manufacturing flowfields is to invest in a CNC cutting machine. CNCstands <strong>for</strong> computer numerical control—it’s <strong>the</strong> lazyman’s solution, as it allows you to create a designin a computer-aided design package, and send it to<strong>the</strong> machine, which will <strong>the</strong>n mill <strong>the</strong> material asdictated by <strong>the</strong> pattern.Increasingly, you will find CNC machines inwell-equipped schools and college design andtechnology departments, so if you’re friendly witha teacher or technician, you may be able tomanufacture some flow fields.Alternatively, <strong>the</strong>re are some fairly simple CNCkits, such as from Parallax, which is a simple CNCmachine <strong>for</strong> light hobby work. It is eminently suited<strong>for</strong> this kind of work, which is very lightweight.The machine is much more af<strong>for</strong>dable, by a numberof orders of magnitude, than commercial CNCmachines, and will find o<strong>the</strong>r applications in an<strong>Evil</strong> <strong>Genius</strong>’s workshop!You need to ensure a good interface between <strong>the</strong>graphite flow field and <strong>the</strong> MEA, so you want toensure that <strong>the</strong> surface of your flow field is assmooth as possible. Wet and dry paper is a goodway to remove imperfections—start with coarsergrits working down to a 600 grit. One thing isessential—work with a flat-bottomed sandingblock, as it is absolutely critical that parallelismis maintained on ei<strong>the</strong>r side of <strong>the</strong> flow fieldplate.Membrane electrode assembliesIn a membrane-based fuel cell, it is <strong>the</strong> assemblyof membrane as gas diffusion electrodes that youwill understand does all of <strong>the</strong> work. It is at <strong>the</strong>junction between membrane, platinum, and electrodeScratch-Built <strong>Fuel</strong> <strong>Cell</strong>s125
Figure 11-8 Always remember to handle MEAs withcotton gloves.Project 32: Making Your Own MEAsFigure 11-7An off-<strong>the</strong>-shelf MEA.that <strong>the</strong> chemical reactions vital to <strong>the</strong> fuel cell’soperation take place. We saw in <strong>the</strong> chapter on PEMfuel cells how this happens.It is possible to buy <strong>the</strong> MEA as a ready-fabricatedcomponent, however, by making your own, yougain a greater degree of control over <strong>the</strong> materialsused in <strong>the</strong> per<strong>for</strong>mance of your MEA, youcan make custom sizes, and are able to produceMEAs at cheaper cost. Also, by making yourown, it is possible to have much greater controlover <strong>the</strong> coating process—this additional flexibilitygives wider scope <strong>for</strong> experimentation and newlearning.The chemical coating of an MEA is very sensitiveto pollutants and very fragile. For this reason, whenhandling MEAs—shop bought, or making yourown—always ensure that you wear fine, clean cottongloves as <strong>the</strong>y ensure that you will not damage <strong>the</strong>MEA. Handle <strong>the</strong>m carefully, as <strong>the</strong>y are very delicate,and try and hold <strong>the</strong>m around <strong>the</strong> edges ifpossible, ra<strong>the</strong>r than making contact with <strong>the</strong> blackcentral portion.Project 32: Making Your Own MEAsFor <strong>the</strong> hardcore fuel cell experimenter, you mightwant to have a go at making your own MEAs. In orderto do this, you are going to need some pretty sophisticatedmaterials and some relatively cheap tools.To recap <strong>for</strong> those that have <strong>for</strong>gotten our littlejourney down PEM avenue, MEA stands <strong>for</strong>Membrane Electrode Assembly.An MEA consists of a proton exchange membrane,Nafion from Du Pont is commonly used.This is sandwiched between ei<strong>the</strong>r a cloth or paperimpregnated with carbon. This <strong>for</strong>ms our GDL orgas diffusion layer. To recap, <strong>the</strong> GDL allows ourgas and water to move to and from <strong>the</strong> platinumcatalyst.126
Figure 11-9A bottle of Nafion solution.We will be using Nafion solution in <strong>the</strong>construction of our own MEAs—this can bepurchased in a variety of percentage solutions.You will also need some Nafion membranein sheet <strong>for</strong>m. Remember, when it arrives in <strong>the</strong>post, resist <strong>the</strong> urge to get it out and start playingwith it, as it is easily damaged.You can obtain both Nafion sheet, and Nafionmembrane from <strong>Fuel</strong> <strong>Cell</strong> Store—this website linktakes you to all <strong>the</strong>ir Nafion products:www.fuelcellstore.com/cgi-bin/tornado/view=NavPage/cat=97If you can do this at a school or college chemistrylab, <strong>the</strong>n use a fume cupboard—this will ensurethat you are not harmed by <strong>the</strong> vapors from <strong>the</strong>boiling hydrogen peroxide or sulfuric acid.However, if you do not have a fume cupboard,ensure that you do this activity outside in a wellventilatedarea to ensure your safety. Make surethat you wear protective clothing while carryingout this activity—some thick acid-proof gloves orgauntlets will ensure that your hands and armsdon’t come into contact with boiling acid. Ensurethat you are wearing safety specs, use a protectiveapron, and ensure you are wearing fairly thickclothing to cover up your arms and legs.In <strong>the</strong> event of a splash, turn off <strong>the</strong> heat, and goindoors immediately, take <strong>the</strong> affected piece ofclothing off, and use water to make sure that nochemical is in contact with your skin <strong>for</strong> too long.Project 32: Making Your Own MEAsFigure 11-10A sample of Nafion membrane.You will need to prepare your Nafion membrane<strong>for</strong> use in your fuel cell. You will need a doubleboiler,sometimes called a Bain Marie, which youwill not be using again <strong>for</strong> food, as we’re goingto be using some nasty chemicals in it.You can make a Bain Marie simply from laboratoryglassware—it just consists of a larger potwhich can be heated to <strong>the</strong> point of water boiling,with a smaller pot inside which is heated indirectlyby <strong>the</strong> hot water. The intermediate step of heating<strong>the</strong> water gives you finer control over <strong>the</strong> temperature,and a more even distribution of heat, whichis useful in this application.127
Project 32: Making Your Own MEAsIt is also handy if you have a setup where youcan heat two pots at <strong>the</strong> same time, as this willallow you to begin to bring ano<strong>the</strong>r bath up totemperature, while <strong>the</strong> one <strong>the</strong> MEA is currently inis coming to <strong>the</strong> end of its cycle.Warning: a metal Bain Marie is not suitable <strong>for</strong>this experiment—you need to ensure that you areusing glass or something inert which will notreact with <strong>the</strong> hydrogen peroxide orsulfuric acid.You will also need a <strong>the</strong>rmometer capable ofmeasuring relatively high temperatures—don’t betempted to use a standard glass <strong>the</strong>rmometer—dip<strong>the</strong> end in <strong>the</strong> hot, boiling water, and you willcertainly have damaged your <strong>the</strong>rmometer—it mighteven crack, leaving <strong>the</strong> mercury or alcohol to leakout. One place you could start your search <strong>for</strong>high-temperature <strong>the</strong>rmometers is online, lookingat supply stores <strong>for</strong> home sweet or candy makers.You are going to need to cut a uni<strong>for</strong>mly sizedpiece of Nafion <strong>for</strong> each MEA in your fuel cellstack.Cut your carbon cloth or paper, so that it is slightlysmaller than <strong>the</strong> Nafion membrane, giving it aborder which can be used to mount <strong>the</strong> membraneas part of a larger sheet of gasket.To prepare <strong>the</strong> membrane, you will need 3%hydrogen peroxide solution, sulfuric acid, andplenty of distilled water.We will be filling <strong>the</strong> larger pan of <strong>the</strong> Bain Mariewith water, which we will bring to <strong>the</strong> boil. Thesmaller pan which sits inside <strong>the</strong> pan will start offwith distilled water. You need to immerse <strong>the</strong> MEAin this water, at a temperature of 176∞ F or 80∞ Cto hydrate <strong>the</strong> membrane <strong>for</strong> a period of around anhour. Use a glass rod to ensure that <strong>the</strong> MEA isfully immersed in <strong>the</strong> water, as its tendency will beto float up.Towards <strong>the</strong> end of <strong>the</strong> hour, you need to bringano<strong>the</strong>r pot—this time with 3% peroxidesolution—up to temperature (176∞ F or 80∞ Cagain). Transfer <strong>the</strong> membrane from one pot to <strong>the</strong>next, and maintain <strong>the</strong> temperature <strong>for</strong> an hour.The membrane may be tricky to transfer—beingtransparent it’s hard to see, and you’ll probablyfind it slippery to handle. There are three goldenrules:1. Don’t drop <strong>the</strong> membrane.2. Don’t puncture or scratch <strong>the</strong> membrane.3. Don’t use a metal object to retrieve <strong>the</strong>membrane.Take <strong>the</strong> pot you used <strong>for</strong> <strong>the</strong> initial distilledwater bath, and transfer a quantity of sulfuric acidinto this pot. Bring it up to <strong>the</strong> temperature of176∞ F or 80∞ C.Take <strong>the</strong> membrane out of <strong>the</strong> hydrogen peroxide,and allow as much of <strong>the</strong> fluid to drip from <strong>the</strong>membrane as you can, and <strong>the</strong>n immerse <strong>the</strong>membrane in <strong>the</strong> sulfuric acid. Use <strong>the</strong> glass rodagain to ensure that <strong>the</strong> membrane sits below <strong>the</strong>surface of <strong>the</strong> hot liquid. Once this has been heated<strong>for</strong> an hour, we will be washing <strong>the</strong> membrane inthree distilled water baths at 176∞ F or 80∞ C.Once this process is complete, allow <strong>the</strong> membraneto dry—ensure that it doesn’t come into contactwith anything metallic, and ensure that <strong>the</strong> air canget to it.Remember when you are finished with yoursulfuric acid to dispose of it in a sensible,responsible manner. Do not store it in any kind ofgeneric container that could be mistaken <strong>for</strong> afood item or cleaning product—make sure youstore it responsibly in a clearly labeled container.128
Preparing <strong>the</strong> GDLRemember <strong>the</strong> gas diffusion layer? Well, you’regoing to have a choice of ei<strong>the</strong>r using carbonpaper, as shown in Figure 11-11, or carbon cloth,as shown in Figure 11-12.The gas diffusion layer is a carbon impregnatedcloth or paper, with a high concentration of platinumwhich acts as a catalyst. For <strong>the</strong> home fuel cellexperimenter, <strong>the</strong>re are a number of ways that wecan prepare <strong>the</strong> GDL.For a range of GDL materials, check out <strong>Fuel</strong><strong>Cell</strong> Store’s page at: www.fuelcellstore.com/cgi-bin/tornado/view=NavPage/cat=56We’re going to discuss a few different options<strong>for</strong> transferring <strong>the</strong> catalyst to <strong>the</strong> carbon cloth orpaper.You’re also going to need some platinum catalystto deposit on <strong>the</strong> interface between your GDL and<strong>the</strong> Nafion membrane. In this respect, you havean array of options open to you. It is quite handyFigure 11-12A sample of e-Tek gas diffusion layer.and easy to buy ready-prepared mixtures of carbonand platinum powder <strong>for</strong> your catalyst. This can beapplied to your GDL. You can get jars of anodeand cathode paste with varying compositions ofcatalysts, which can be applied to your GDL.Remember, <strong>for</strong> repeatability, always make finemeasurements of <strong>the</strong> quantities of chemicals thatyou are using, so that you can manufacture similarfuel cells in <strong>the</strong> future. Compare different loadingsof platinum catalyst to see how it affects <strong>the</strong> per<strong>for</strong>manceof your fuel cell.Project 32: Making Your Own MEAsFigure 11-11A sample of carbon paper.Figure 11-13Jars of anode and cathode pastes.129
measured amounts of platinum compound intoyour MEA.The platinum printing process was developed byW. Willis in 1873. For fuel cells, it is perfect as itdeposits a layer of platinum black onto <strong>the</strong> MEA—this is especially useful as platinum black is one of<strong>the</strong> best <strong>for</strong>ms of platinum <strong>for</strong> our application.You won’t find platinum printing kits in yourstandard photo shop, as <strong>the</strong> process is now largelyused <strong>for</strong> art prints, or prints with a very high resalevalue. However, <strong>the</strong>re are a couple of onlinevendors that sell <strong>the</strong> chemicals <strong>for</strong> this process.Project 32: Making Your Own MEAsFigure 11-14 Fine scales <strong>for</strong> carefully measuringchemical quantities.High-voltage depositionOne way in that it is possible to transfer platinumto <strong>the</strong> GDL is through high-voltage vaporization offine platinum leaf. By passing a very high voltagethrough a fine wire or leaf of platinum, it is possibleto vaporize it, and small pieces of platinum willbe deposited on any adjacent surfaces that areclose by.There are a couple of books that discuss makingdevices to vaporize fine wire in detail:Two books that I can highly recommend:Gordon Mc Comb’s Gadgeteers Goldmine—Gordon Mc Comb, McGraw-Hill, New YorkElectronic Gadgets <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>—RobertIaninni, McGraw-Hill, New YorkPlatinotype—photochemicaldepositionPlatinum is firmly embedded in <strong>the</strong> history ofphotography, and as such, platinum printing, whilebeing expensive, does furnish <strong>the</strong> potential fuel cellbuilder with a method of accurately depositingHere is a great source of platinum printing kits,and all <strong>the</strong> chemicals you need to platinum printare also available individually:www.photographers<strong>for</strong>mulary.comFollow <strong>the</strong> instructions in <strong>the</strong> kit (which maydiffer depending on <strong>the</strong> supplier). You will need tocoat your pieces of GDL as if <strong>the</strong>y were photographicpaper, but ra<strong>the</strong>r than enlarging an imageonto <strong>the</strong>m, I suggest:●●Leaving <strong>the</strong>m out in <strong>the</strong> sun <strong>for</strong> UVexposureIf you have a UV light box (say <strong>for</strong> etchingprinted circuit boards), you can use this toexpose <strong>the</strong> piece of GDL.Remember, photographic paper takes a negativeimage, and reverses it, so <strong>for</strong> areas of high-densityblack, we need to expose <strong>the</strong> GDL to bright whitelight. Once you’ve made <strong>the</strong> exposure, don’t <strong>for</strong>getthat you’ll need to process your GDL using <strong>the</strong>chemicals in <strong>the</strong> kit, in order to fix <strong>the</strong> platinumblack.Throughout <strong>the</strong> processing, keep a keen eye onwhat side you applied <strong>the</strong> platinum to, as <strong>the</strong> fuelcell will only work if <strong>the</strong> platinum is in contactwith <strong>the</strong> Nafion membrane.130
ElectroplatingAno<strong>the</strong>r option available to you is to electroplateplatinum onto your GDL. To do this, you connect<strong>the</strong> GDL to <strong>the</strong> negative terminal of a power supply,a piece of platinum scrap to <strong>the</strong> positive, andimmerse <strong>the</strong> two objects in a solution of platinumsalts.www.caswellplating.com sells a wide range ofhome electroplating kits and accessories; however,<strong>the</strong>y do not supply kits specifically <strong>for</strong> platinumplating. Their website has a useful <strong>for</strong>um, with lotsof in<strong>for</strong>mation about electroplating with differentmetals, and this would be a good place to start ifyou want to investigate platinum electroplating.If you have bought <strong>the</strong> above-mentioned platinotypeprocess kit, you should have some potassiumtetrachloroplatinate included in <strong>the</strong> kit—this is aplatinum salt, and all you need now is some platinum<strong>for</strong> <strong>the</strong> anode, which could be a piece of platinumleaf.Platinum leafYou can transfer platinum leaf very easily to carboncloth or paper, by simply holding <strong>the</strong> leaf against<strong>the</strong> GDL and rubbing hard on <strong>the</strong> back with apointed but not sharp object (e.g., <strong>the</strong> wrong end ofa ballpoint pen).The <strong>Fuel</strong> <strong>Cell</strong> Store sells a pair of aluminumplates suitable <strong>for</strong> hot-pressing your MEA—<strong>the</strong>stock number is 590163.You will now need to coat your GDL with someNafion solution. Remember Figure 11-9? Ensurethat you do not get any metal in contact with <strong>the</strong>Nafion—you can get cheap plastic brushes <strong>for</strong>coating pastries with egg or kiddies’ art-brushes.Just coat one side of <strong>the</strong> GDL (<strong>the</strong> side with <strong>the</strong>platinum on)—you don’t need to saturate <strong>the</strong>carbon cloth or paper, but just ensure that <strong>the</strong>surface is coated.You’re also going to need an oven <strong>the</strong>rmometer,of <strong>the</strong> type you use to check that your turkey is at<strong>the</strong> right temperature.Remember that we said earlier what a fantasticlubricant graphite was—well, we’re going to needsome graphite powder now (see Figure 11-16), toensure that <strong>the</strong> Nafion doesn’t stick to <strong>the</strong> plateswe are using to clamp <strong>the</strong> assembly toge<strong>the</strong>r. Thisis just like greasing a pan when we are cooking.Rub <strong>the</strong> graphite into <strong>the</strong> surfaces of <strong>the</strong> plates,Project 32: Making Your Own MEAsPutting it all toge<strong>the</strong>r ...Once you’ve impregnated your GDL with platinum,and prepared your Nafion membrane, <strong>the</strong> nextstep is to assemble your MEA.To do this, you are going to need a couple ofstiff sheets of metal and some clamps to applypressure between <strong>the</strong> two sheets. You might findthat you can get a ready-made assembly from apaper-making kit—<strong>the</strong> key is, you need to ensurethat <strong>the</strong> materials are happy being heated in<strong>the</strong> oven.Figure 11-15Graphite powder.131
Figure 11-18 Home-built fuel cell (note electrodes andsandwich construction).Project 32: Making Your Own MEAsFigure 11-16tube barbs).which will be in contact with <strong>the</strong> clamped MEAassembly.Graphite powder is available in small bottlesfrom <strong>Fuel</strong> <strong>Cell</strong> Store—<strong>the</strong> stock number is 590263.We’re now going to assemble <strong>the</strong> MEA—this isa bit like putting a burger toge<strong>the</strong>r. First, place <strong>the</strong>first piece of GDL platinum side up in <strong>the</strong> centerof one of <strong>the</strong> plates. Lay <strong>the</strong> Nafion membraneover this, ensuring that it overlaps on all sides, and<strong>the</strong>n lay <strong>the</strong> final piece of GDL on top, platinumside down. Carefully place <strong>the</strong> final plate on top,graphite side in contact with <strong>the</strong> piece of GDL, andfirmly clamp this assembly toge<strong>the</strong>r.Figure 11-17Home-built fuel cell (note fixings andHome-built fuel cell, side view.Now bake …Using <strong>the</strong> oven <strong>the</strong>rmometer to check <strong>the</strong> temperatureis accurate (never rely on <strong>the</strong> temperatureindications on your oven dial—<strong>the</strong>y’re not accurateenough), bake at 194∞ F or 90∞ C <strong>for</strong> an hour, and<strong>the</strong>n slowly over <strong>the</strong> course of <strong>the</strong> next half anhour, turn <strong>the</strong> knob on your oven up to 266∞ F or130∞ C. After <strong>the</strong> sandwich has been in <strong>for</strong> an hourand a half, whip <strong>the</strong> lot out, tighten <strong>the</strong> clampseven more (using tea towels and oven gloves toavoid serious burns). Now, put <strong>the</strong> sandwich backin your oven, and whack <strong>the</strong> temperature control upto its maximum. Watch <strong>the</strong> oven <strong>the</strong>rmometercarefully—we want to get <strong>the</strong> oven up to 266∞ F or130∞ C, but no more! Maintain this temperature <strong>for</strong>a couple of minutes. Then switch your oven off,remove <strong>the</strong> clamped assembly, and leave it to coolon a trivet until it reaches ambient temperature.GasketsYou will need to mount your MEA in a gasket,which will ensure a good interface between <strong>the</strong>MEA and adjacent flow fields, and will alsoprevent it from diffusing from one side to <strong>the</strong>o<strong>the</strong>r. Look <strong>for</strong> a thin silicone rubber sheet—youwill need to cut two pieces, one <strong>for</strong> ei<strong>the</strong>r side of<strong>the</strong> MEA, and use a silicone glue to run a thinbead of adhesive around <strong>the</strong> overlapping piece of132
Nafion membrane. Remember, your gasket willneed a hole in <strong>the</strong> middle which is <strong>the</strong> same size asyour GDL, holes in <strong>the</strong> corners to allow <strong>the</strong> nutsand bolts or threaded rods to pass through, andholes where <strong>the</strong> hydrogen (and oxygen if present)gas supply lines are.<strong>Fuel</strong> <strong>Cell</strong> Store sells a range of different materialsthat can be used to manufacture gaskets <strong>for</strong> yourMEA. Look on <strong>the</strong>ir website at www.fuelcellstore.com/cgi-bin/tornado/view=NavPage/cat=62, andyou will see that <strong>the</strong>y sell Teflon, rubber, siliconeand Mylar—all suitable materials <strong>for</strong> different fuelcell gasketing applications.ElectrodesYou’re going to need a metal electrode at ei<strong>the</strong>rend of your fuel cell assembly to tap off <strong>the</strong> power.There are a couple of ways of doing this. You canuse metal end-plates, however, this requires thatyou pay great attention to insulating <strong>the</strong> fixingsused to hold your fuel cell toge<strong>the</strong>r, or you cansimply insert a sheet of metal between <strong>the</strong> endplateand <strong>the</strong> flow field at each end.Fixing it all toge<strong>the</strong>rYou are going to need some fixings to hold yourfuel cell toge<strong>the</strong>r—you can ei<strong>the</strong>r use nuts andbolts, or threaded rods. However, <strong>the</strong> key is toremember to insulate <strong>the</strong> portion of <strong>the</strong> thread inside<strong>the</strong> fuel cell, to prevent it shorting electrodes andflow fields. This can be simply accomplished withsome heat-shrink tubing.Fur<strong>the</strong>r reading●Hurley, P., Build Your Own <strong>Fuel</strong> <strong>Cell</strong>s, WheelockMountain Publications Wheelock, VT.This is an invaluable reference <strong>for</strong> those wishingto take this even fur<strong>the</strong>r. It expands upon methodsof platinum deposition and constructing MEAs inmuch more detail than is within <strong>the</strong> scope of thisbook, and is a mine of useful in<strong>for</strong>mation <strong>for</strong> fur<strong>the</strong>rresearch.Project 32: Making Your Own MEAs133
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Chapter 12Hydrogen SafetyDangerous hydrogen?Safety concerns or flimsymyth?As with any technology, <strong>the</strong>re is generally a fairshare of urban myths and legends that circulate,which aren’t true, don’t give us useful in<strong>for</strong>mation,and end up cultivating a distrust or fear of a certaintechnology.It is <strong>the</strong> same with hydrogen and fuel cells. Inthis chapter, we are going to debunk and demystifysome of <strong>the</strong> half-truths surrounding hydrogen, andrestore some confidence in <strong>the</strong> technology. This isgoing to be followed by a coverage of some of <strong>the</strong>health and safety aspects you should be aware ofwhen experimenting with hydrogen.Hydrogen is safe, but with any <strong>for</strong>m of chemicalor experimentation, it is important to treat all procedureswith due care and respect.Hydrogen has got a bit of a bad press from manydifferent sources. For many years, graceful,lighter-than-air airships, filled with hydrogen gas,graced <strong>the</strong> skies. Following <strong>the</strong> Hindenburg disaster,<strong>the</strong> airship dropped into relative obscurity. Thehydrogen gas that it was filled with is often blamedas <strong>the</strong> culprit, but <strong>the</strong> hydrogen burned upward. Infact, this is one of <strong>the</strong> inherent safety features ofhydrogen. Because hydrogen burns “upwards” itwould not have affected <strong>the</strong> canvas below; however,it has been proved that it was in fact <strong>the</strong> silvercoating of <strong>the</strong> ship that caused <strong>the</strong> most damage—this coating was covered with powdered aluminum.Testament to this was <strong>the</strong> fact that out of 37 casualties,35 died from jumping to <strong>the</strong> ground froma height. Diesel burns were also responsible <strong>for</strong>a lot of injury.The fact that hydrogen is so light means thatwhen it is lit, it burns “up and away” from you.Contrast this to say, petrol, where fumes are heavy,and creep along <strong>the</strong> ground—<strong>the</strong> number of carmechanics who have received injury from firesigniting petrol vapors that have slowly accumulatedin pits is testament to this. Whereas with hydrogen,so long as <strong>the</strong>re is sufficient ventilation, and room<strong>for</strong> it to escape, it will rise up and dissipate.However, when designing buildings to househydrogen equipment <strong>the</strong>y must not have a “sealedcap,” as rising hydrogen can accumulate here.It’s easy to read into <strong>the</strong> name of “<strong>the</strong> hydrogenbomb” <strong>the</strong> notion that hydrogen is dangerous.We have all seen <strong>the</strong> devastating mushroom cloudsthat nuclear weapons leave in <strong>the</strong>ir wake. Since<strong>the</strong>n, <strong>the</strong> hydrogen bomb has done nothing <strong>for</strong> <strong>the</strong>good name of hydrogen, linking a potential saviorof our energy future with dangerous nuclear technology.The hydrogen bomb contained tritium,radically different from <strong>the</strong> hydrogen that would beused in <strong>the</strong> hydrogen economy. Tritium is an isotopeof hydrogen, and <strong>the</strong> sophistication and technologyrequired to make an atomic bomb just isn’taccessible. The mechanism that a hydrogen bombuses to create its massive devastation involves <strong>the</strong>fusion of hydrogen atoms, something which isquite different from <strong>the</strong> chemical processes thattake place when burning hydrogen, and so <strong>the</strong> twoshould not be confused.Fur<strong>the</strong>rmore, a number of accidents in spacehave become linked in <strong>the</strong> public mind withhydrogen—this just isn’t fair!The Apollo 13 mission in space seems to havemysteriously become associated with hydrogen in135Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
Figure 12-1The Hindenburg disaster.H y d r o g e n S a f e t ymany people’s minds—this is ano<strong>the</strong>r urban myth.In 1970, on April 11th, NASA launched <strong>the</strong>13th Apollo mission. During <strong>the</strong> flight, some fansinside one of <strong>the</strong> ship’s oxygen tanks were turnedon, and <strong>the</strong>re was a short circuit, setting <strong>the</strong> fan onfire. As a result, <strong>the</strong> oxygen tanks were weakenedFigure 12-2The hydrogen bomb.and explosive. I don’t know how much you knowabout astronauts, but <strong>the</strong>y don’t get on so wellwithout a supply of oxygen. Luckily, missioncontrol were able to work out a solution <strong>for</strong> <strong>the</strong>astronauts in space, and in true prototype experimentfashion, duct tape was employed to stick thingstoge<strong>the</strong>r. (See Figure 12-3.) Contrary to popularbelief, hydrogen and fuel cells were not in any wayrelated to this disaster.While <strong>the</strong> Apollo 13 mission can be shown not tocast a slur on hydrogen or fuel cell technology, <strong>the</strong>mission does provide a fantastic endorsement <strong>for</strong> ducttape (a marvelous product!) which saved <strong>the</strong> day at<strong>the</strong> last minute by assisting <strong>the</strong> astronauts in makinga jerry-rig fix, which safely returned <strong>the</strong>m home.Duct tape is long overdue a presidential Medal ofFreedom <strong>for</strong> outstanding service to <strong>the</strong> world!The Challenger disaster in 1986 also linkedhydrogen with safety, and has led many to believethat hydrogen technologies cannot be safe. However,NASA have concluded that <strong>the</strong> disaster was not136
Figure 12-3 Jerry-rigged solution which saved <strong>the</strong>astronauts of Apollo 13.caused in any way by hydrogen, instead it wascaused by faulty “O-rings.”Fortunately, all of <strong>the</strong>se instances do not relateto how hydrogen would be used in a hydrogeneconomy, and any speculation arising from <strong>the</strong>seevents can be discounted as hysterical overreaction.Hydrogen safetyin vehiclesAny fuel which embodies a lot of energy in a smallspace has <strong>the</strong> potential to cause danger. If we fillup a car with petrol, we take a calculated risk, buteverything is done to reduce that risk. Filling a carwith hydrogen would involve no more risk.One of <strong>the</strong> things about hydrogen is that it islighter than air. This means that if you spill some,ra<strong>the</strong>r than landing on <strong>the</strong> ground, it dispersesand floats to <strong>the</strong> sky. This is quite an advantage,when you come to consider how much petrol anddiesel has polluted our watercourses. Fur<strong>the</strong>rmore,you won’t stain your clo<strong>the</strong>s with hydrogen as itjust disperses.There is a lot of work going into developingstrong, robust hydrogen storage tanks that, in <strong>the</strong>case of vehicles, can withstand even <strong>the</strong> mostcatastrophic crashes. Sure, hydrogen has <strong>the</strong>potential to explode, but drivers of petrol vehicleshave happily exposed <strong>the</strong>mselves to <strong>the</strong> same risks<strong>for</strong> many decades. Following extensive crashtesting, BMW concluded that in a 55-mph impact,hydrogen vehicles are no more dangerous thancarbon-based vehicles.One of <strong>the</strong> considerations that manufacturerstake into account is that <strong>the</strong>re can be no accumulationof hydrogen in <strong>the</strong> vehicle should a leakdevelop.But what if hydrogen leaks from your car?Research has shown that if hydrogen leaks from avehicle tank at a rate of 3000 cubic feet per minuteand is lit, <strong>the</strong> temperature inside <strong>the</strong> vehicle doesnot climb any more than 1 or 2 degrees—vehiclesget hotter than this sitting in <strong>the</strong> sun!This is because hydrogen produces little radian<strong>the</strong>at. When a carbon-based fuel burns, particlesof hot carbon (soot) transfer heat to <strong>the</strong>surroundings—with hydrogen <strong>the</strong>re is no soot andso less radiant heat transferred.Hydrogen is already used extensively in industry,where safe methods <strong>for</strong> <strong>the</strong> transportation andstorage of hydrogen have been developed.The recent Buncefield Oil Depot disaster in <strong>the</strong>UK, and countless o<strong>the</strong>r accidents around <strong>the</strong>world involving oil, have highlighted <strong>the</strong> dangerousnature and shortcomings of storing hydrocarbonfuels—storing hydrogen would be no moredangerous.One of <strong>the</strong> problems with hydrogen is that itburns with a colorless flame—this means that wecan’t always clearly see a hydrogen fire. If yoususpect a hydrogen fire, do not try to approach it,and do not try to identify it by “feeling” heat.The correct method is to take a long-handledbroom, and waft <strong>the</strong> bristles of <strong>the</strong> broom aroundwhere you suspect <strong>the</strong>re is a hydrogen flame.If hydrogen is burning, <strong>the</strong> bristles on <strong>the</strong> endH y d r o g e n S a f e t y137
gases or fuels, that you are working in an area thatis well ventilated to allow any gases that areproduced to escape, preventing build-up, andexplosion hazards.Make sure you keep all bottles of chemicalsclearly labeled and never assume that <strong>the</strong> label isright. Always treat chemicals as an “unknownquantity”—a clear liquid could be tap water, but<strong>the</strong>n it could also be concentrated acid!Figure 12-4Identifying a hydrogen fire with a broom.of <strong>the</strong> brush will catch light (see Figure 12-4).If you identify a fire, quickly pull <strong>the</strong> broom away,and call <strong>the</strong> fire brigade. If you can safely isolate<strong>the</strong> supply of gas, without getting anywhere near<strong>the</strong> flame, <strong>for</strong> example, by a remote valve, or gasshutoff safety system, do so.Running your experimentssafelyIn order to avoid accidents and run a safeexperimentation area, if you have any storedflammable gas, in bottles, and/or hydrides, makesure that <strong>the</strong>y are stored correctly and labeled witha suitable label, such as that shown in Figure 12-5.Make sure that whenever you are carrying outexperiments with hydrogen, methanol, or o<strong>the</strong>rIf you are working with <strong>the</strong> small quantities ofhydrogen produced by a little PEM electrolyzer,this isn’t going to happen, but if you start usinghydrogen from a cylinder, or from a laboratorytap, or working with larger quantities of hydrogenwithout proper ventilation, beware!In <strong>the</strong> event that a person is asphyxiated byinhalation of hydrogen gas:The person should be moved to an area o<strong>for</strong>dinary atmosphere, ensuring that you do notendanger yourself in <strong>the</strong> process. Open windows,provide as much ventilation and access to air aspossible, while making sure not to switch onany electrical appliances or cause any sourcesof ignition.H y d r o g e n S a f e t yFigure 12-5 Clear labeling is essential. Figure 12-6 No smoking.138
Figure 12-9 A hydrogen safety sensor. Imagecourtesy <strong>Fuel</strong>cellstore.com.H y d r o g e n S a f e t yFigure 12-7Finally, something that should seem incrediblyobvious: <strong>the</strong>re should be no smoking. Rein<strong>for</strong>cethis message by photocopying Figure 12-6 anddisplaying it around your working area.For some of <strong>the</strong> experiments in this manual, youare going to be using methanol, alkalines, andsodium borohydride. These will all get on yourclo<strong>the</strong>s and skin, and irritate or poison you if youare not careful, so do <strong>the</strong> sensible thing, and getyourself a lab coat. They are available in a varietyFigure 12-8you look cool.Lab coat.Safety glasses—a must, and <strong>the</strong>y makeof ra<strong>the</strong>r fetching styles, and in a variety ofexciting colors—white! They also have <strong>the</strong> sideeffectof making you look incredibly purposefuland professional in your experimentation, which isto be encouraged at all costs, as people will not<strong>the</strong>n bo<strong>the</strong>r to distract you <strong>for</strong> chores or menialtasks, if you seem to be deep in <strong>the</strong> throes ofmaking some discovery which could qualify you<strong>for</strong> <strong>the</strong> next Nobel prize.The o<strong>the</strong>r thing which is a must-have, both <strong>for</strong>“<strong>the</strong> look” and safety is a pair of safety glasses.You only get one set of eyes, and if you flicksomething nasty in <strong>the</strong>m, you could damage orimpair your vision permanently, so make sure youwear <strong>the</strong>m when working with chemicals, settinglight to things, or cutting materials—where bits ofmaterial are liable to fly off and hurt you!If you start getting serious about fuel cellexperimentation, and decide to invest in largePEM electrolyzers, or regularly work with cylindersof hydrogen, or, if you are a school or university,you might like to consider investing in a gasdetection system. <strong>Fuel</strong> <strong>Cell</strong> Store sell a hydrogensafety sensor, currently retailing at just over$100 (Part No. 570150), which could be a goodinvestment as you get more serious about <strong>the</strong> hobby.Above all, use your commonsense, and stay safe.139
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Chapter 13Hydrogen Transport<strong>Fuel</strong> cell carsTo appreciate <strong>the</strong> differences between fuel cellvehicles and o<strong>the</strong>r types of vehicles, we have tounderstand some of <strong>the</strong> energy transfers that aretaking place. Ultimately, when we are talkingabout transport, we need to produce mechanicalenergy to turn <strong>the</strong> wheels of <strong>the</strong> car and make <strong>the</strong>thing go; however, although internal combustionengines can produce mechanical power directly,<strong>the</strong>y only do so efficiently over a narrow powerband, whereas electric motors produce a hightorque over a wide power band. This is why carmanufacturers are looking into hybrid vehicles tocombine <strong>the</strong> strengths of both <strong>the</strong> power densitythat can be stored in fuels <strong>for</strong> <strong>the</strong> internal combustionengine, and <strong>the</strong> efficiency over a range of loads of<strong>the</strong> electric motor. See how battery vehicles andfuel cells fit into this energy conversion sequencein Figures 13-1 and 13-2.Cars today tend to use four-stroke, internalcombustion engines. These engines ei<strong>the</strong>r burnpetrol or diesel, but in a more limited capacity,some vehicles will burn LPG, biodiesel, orbioethanol.While <strong>the</strong> effects of releasing carbon into <strong>the</strong>atmosphere can be mitigated by using differentfuels such as biomass or biogas, it does not change<strong>the</strong> fact that <strong>the</strong> petrol engine, being a heat engine,is horribly inefficient, and converts not a lot of <strong>the</strong>chemical energy embodied in <strong>the</strong> fuel into actualdelivered power.In addition, <strong>the</strong>re is ano<strong>the</strong>r good reason <strong>for</strong>rejecting <strong>the</strong> internal combustion engine. Look atall <strong>the</strong> different byproducts that pollute ourenvironment that come out of your exhaust pipe.Fur<strong>the</strong>rmore, by burning fuel with air, a cocktailof nasty gases is released, which contains not onlyCO 2, but also NO Xand SO X, as well asparticulates.In addition, internal combustion engines onlyreally have a usable efficiency within a narrowpower band. This means that we need a gearboxwhich adds fur<strong>the</strong>r weight to <strong>the</strong> vehicle, and aFigure 13-1 Production of electrical power. Figure 13-2 Production of mechanical power.141Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
H y d r o g e n T r a n s p o r tFigure 13-3 The internal combustion engineproduces all sorts of nasty emissions.clutch to engage and disengage <strong>the</strong> gearbox from<strong>the</strong> engine. All in all, this is not very satisfactory.One criticism that people often have of fuel cellvehicles is that <strong>the</strong>re is an argument <strong>for</strong> usingfossil fuels to produce hydrogen. You, in effect,create a “long tailpipe” with all your vehicle’semissions coming from a centrally located, largetailpipe—<strong>the</strong> power station’s chimney! This is acompelling reason why we need to look to clean,green sources of energy, in order to make sure thatour future transport options have a reducedenvironmental impact.Electric motors fit a vehicle’s requirementsmuch more closely. At low rpm, <strong>the</strong>y produce <strong>the</strong>most torque—this is when a vehicle requires <strong>the</strong>extra energy to get it started. In addition to this,regenerative braking can be used, where kineticenergy from <strong>the</strong> car’s <strong>for</strong>ward motion can berecovered by using <strong>the</strong> motor as a brake, generatingenergy in <strong>the</strong> process which can be used to chargebatteries and produce hydrogen.The limitation <strong>for</strong> electric vehicles has alwaysbeen <strong>the</strong> battery technology. Batteries are heavy,storing not a lot of energy <strong>for</strong> <strong>the</strong>ir weight. Bycontrast, hydrocarbon fuels provide a lot of energy<strong>for</strong> <strong>the</strong>ir weight, and hydrogen produces a fantasticamount of energy <strong>for</strong> its weight.In addition to this, users have always favoredconvenience—a battery car takes a long timeto “charge up,” and <strong>the</strong>n can only run <strong>for</strong> a shortamount of time.Hydrogen sidesteps <strong>the</strong>se problems with batterytechnology—a car can be fueled in around fiveminutes, and <strong>the</strong>n <strong>the</strong> vast amount of power storedin <strong>the</strong> lighter-than-air hydrogen gas is convertedto electrical energy, which in turn drives aconventional electric motor.This gives us <strong>the</strong> best of both worlds—anenergy-dense power source, with an efficientproducer of kinetic energy.There are already a large array of hydrogenfuel cell concept cars. A quick browse of anymanufacturer’s website will yield <strong>the</strong>ir particularimplementation of fuel cell technology; however,most of <strong>the</strong>se are based on <strong>the</strong> same fuel celltechnologies from only a handful of suppliers.We can take a look at <strong>the</strong> “fuel cell cars gallery”at <strong>the</strong> end of this chapter <strong>for</strong> more details.<strong>Fuel</strong> cell vehicletechnologyWhen we look at a fuel cell vehicle, we notice that<strong>the</strong>re are a number of significant differences.First and most apparent is under <strong>the</strong> hood—nointernal combustion engine, just a fuel cell andelectric motor!Figure 13-4Under <strong>the</strong> hood of a fuel cell car.142
Figure 13-5of a car.Secondly, a little more complexity needs to gointo <strong>the</strong> engineering of <strong>the</strong> fuel tanks—ra<strong>the</strong>rthan a fairly simple metal can, more complexarrangements need to be made <strong>for</strong> storing hydrogen.We explored some of <strong>the</strong>se in <strong>the</strong> earlier chapteron storing hydrogen.Thirdly, when we come to fill <strong>the</strong> car, ra<strong>the</strong>rthan using a simple nozzle, we have a morecomplicated coupling that allows transfer of <strong>the</strong>hydrogen under pressure.Figure 13-6Hydrogen storage tanks under <strong>the</strong> seatA hydrogen coupling on a car.Iceland, which has committed itself to a hydrogeneconomy, opened <strong>the</strong> world’s first hydrogen fillingstation in Reykjavik in April 2003. Hydrogen isproduced onsite by electrolysis. The stationprovides hydrogen <strong>for</strong> a fleet of hydrogen-poweredbuses. Interestingly, <strong>the</strong>re is no roof to this fuelingstation—this has been done to prevent <strong>the</strong> potentiallyexplosive build-up of hydrogen which couldaccumulate.A number of vehicle manufacturers haveannounced <strong>the</strong>ir intentions to develop, or currentlyhave hydrogen fuel cell powered vehicles.That list includes: The Ford Motor Group, whichincorporates Volvo, Mazda, and Jaguar; GeneralMotors (responsible <strong>for</strong> producing Vauxhall carsin <strong>the</strong> UK); Honda; BMW; Nissan; and Hyundai.Nearly all of <strong>the</strong> major car manufacturers arenow showing demonstration models of fuel cellcars at world motor shows. While <strong>the</strong>re are no fuelcell cars available to <strong>the</strong> general public at this time,<strong>the</strong> technology is certainly reaching maturity—manufacturers predict that we can expect to seefuel cell models launched around 2010 <strong>for</strong> generalsale. However, one of <strong>the</strong> main barriers towidespread adoption is <strong>the</strong> lack of hydrogen fillingstations, which will be an obvious concern <strong>for</strong>consumers.At its North American headquarters in Torrance,Cali<strong>for</strong>nia, Honda are exhibiting <strong>the</strong>ir “HomeEnergy Station,” a package that promises to offercombined heat and power <strong>for</strong> <strong>the</strong> home, as well asproviding a source of clean hydrogen <strong>for</strong> poweringHonda fuel cell vehicles.One of <strong>the</strong> main barriers to innovation is <strong>the</strong> costof <strong>the</strong> exotic materials required to manufacture <strong>the</strong>fuel cells. The platinum used <strong>for</strong> catalysts isexpensive, so current research is focusing aroundtrying to eliminate, or at least reduce, <strong>the</strong> amountof platinum inherent in <strong>the</strong> design of fuel cells.There are already promising results—as recentlyas 2002, fuel cells had a platinum content of£600 per kW output; however, we now have cellscontaining around £20 per kW output. Fur<strong>the</strong>radvances will doubtless be made.H y d r o g e n T r a n s p o r t143
Figure 13-7filling station.A specially constructed hydrogenFor long-distance, low-occupancy journeys,motorbikes present a more efficient solution <strong>for</strong>personal transport than cars. What is <strong>the</strong> sense intransporting over a ton of vehicle, to movea person who weighs 80 kg?A number of manufacturers have launchedsmall bikes and mopeds powered by fuel cells.Particularly promising is <strong>the</strong> ENV fuel cell bike,which offers a stylish alternative to conventionalpetrol bikes.In Europe, <strong>the</strong>re are a number of countries tryingout fuel cell buses as a clean alternative <strong>for</strong> publictransport. While <strong>the</strong>y have not been widely adopted,Figure 13-8ENV fuel cell bike.<strong>the</strong> technology is under test and development, andshows much promise <strong>for</strong> <strong>the</strong> future.H y d r o g e n T r a n s p o r tFigure 13-9A London bus—powered by hydrogen. Image courtesy Ballard.144
In this experiment, we will be building a simplefuel cell car, which you can use as a base <strong>for</strong>experimentation to investigate <strong>the</strong> science of fuelcell vehicles. This car is of a very simple design,and functional ra<strong>the</strong>r than aes<strong>the</strong>tic. There arecompetitions <strong>for</strong> fuel cell vehicles such as this, and<strong>the</strong>re is a lot of potential <strong>for</strong> flexibility in <strong>the</strong>design of fuel cell cars. Once you have built thissimple model, you should have a grasp of <strong>the</strong> basicprinciples of fuel cell vehicles. Use this project asa springboard <strong>for</strong> experimentation, and try andenhance <strong>the</strong> per<strong>for</strong>mance of this simple model—make it more lightweight, add bearings, reducefriction, improve balance, improve contact with <strong>the</strong>road–<strong>the</strong> list of engineering topics where thissimple vehicle can take you is endless.●●●●●●●●●●●●<strong>Fuel</strong> cell car competition kit (<strong>Fuel</strong> <strong>Cell</strong> Store PartNo: 7110303) containing:Reversible fuel cellSmall motor with wiresMotor mount4 small screws <strong>for</strong> motor mount1 small screw to secure motorTubing4 wheel hubs4 O-ring tiresGenerous selection of small gears2 axlesProject 33: Building a Simple <strong>Fuel</strong> <strong>Cell</strong> CarCorrugated plastic, correx or corroflute●●●●Hydrogen and oxygen 30-ml cylinders (<strong>Fuel</strong> <strong>Cell</strong>Store Part No: 7110307)Box of matchesPhilips screwdriverCraft knifeYou can purchase a kit (Figure 13-10) from <strong>Fuel</strong><strong>Cell</strong> Store, which contains all <strong>the</strong> fuel cell andmechanical components needed to produce a simplefuel cell car. The kit comes with wheels, tires, axles,gears—everything except <strong>the</strong> chassis and storage ofhydrogen—so this is a good way to get started.Figure 13-10cell car.Kit of components <strong>for</strong> <strong>the</strong> simple fuelP r o j e c t 3 3 : B u i l d i n g a S i m p l e F u e l C e l l C a r145
P r o j e c t 3 3 : B u i l d i n g a S i m p l e F u e l C e l l C a rFigure 13-11The components <strong>for</strong> <strong>the</strong> simple fuel cell car.Once everything is out of <strong>the</strong> box, and you lay itout, it should look something like Figure 13-11.I tell you to get corrugated plastic <strong>for</strong> a reason.It is perfectly possible to buy corrugated card orfoamboard, or thin plastic, or any o<strong>the</strong>r manner ofmaterials from which to make your fuel cell carbase. However, by its nature, corrugated plastic isvery lightweight, yet stiff and rigid. It also has <strong>the</strong>useful property that <strong>the</strong> plastic tubes created by <strong>the</strong>corrugations provide a very convenient means ofanchoring your axles, and remove all <strong>the</strong> complexityof bearings and axle mounting. As you experiment,and decide to work with different materials—without<strong>the</strong> corrugations—small lengths of drinking strawcan be used instead to hold <strong>the</strong> axles in place.The first step is to take <strong>the</strong> plastic wheel hubs(<strong>the</strong>re should be four of <strong>the</strong>m) and <strong>the</strong> rubberO-rings out of <strong>the</strong> box. It is a simple matter ofpushing <strong>the</strong> O-rings onto <strong>the</strong> plastic hubs to <strong>for</strong>m<strong>the</strong> finished wheels. (Take a peek at Figure 13-12.)The next stage is to assemble <strong>the</strong> motor into itsmetal mounting cage. The motor has a circularprotrusion at one end, which supports <strong>the</strong> rotatingshaft. The metal cage has a circle to match this atone end. The motor should be mounted with <strong>the</strong>shaft pointing through that hole, as shown inFigure 13-13.Once you have done this, look at <strong>the</strong> back of <strong>the</strong>motor. You will see that <strong>the</strong> bottom of <strong>the</strong> metalcage protrudes past <strong>the</strong> back of <strong>the</strong> motor. You willFigure 13-12 Assemble <strong>the</strong> wheel hubs and O-ring tires. Figure 13-13 Insert <strong>the</strong> motor in <strong>the</strong> cage.146
Figure 13-14also notice on <strong>the</strong> plastic backing of <strong>the</strong> motor that<strong>the</strong>re are two small holes. Firstly, you should be ableto gently bend this piece of metal over <strong>the</strong> back of<strong>the</strong> motor, so that <strong>the</strong> small hole in <strong>the</strong> center alignswith <strong>the</strong> small hole on <strong>the</strong> back of <strong>the</strong> motor.It is <strong>the</strong>n simply a matter of taking <strong>the</strong> smallestscrew supplied in <strong>the</strong> box, and anchoring <strong>the</strong> motorto <strong>the</strong> cage by securing it, as shown in Figure 13-15.Now, we come to manufacturing <strong>the</strong> chassis. Forthis, you will need a small piece of corrugated plasticwhich is 115 mm by 175 mm. One of <strong>the</strong> things thatyou need to ensure is that <strong>the</strong> “corrugations,” or linesin <strong>the</strong> plastic, run across <strong>the</strong> short side of <strong>the</strong> plastic.This is essential as, as mentioned be<strong>for</strong>e, we will beusing <strong>the</strong>se corrugations to mount our axles.Refer to <strong>the</strong> cutting diagram <strong>for</strong> <strong>the</strong> next step.The diagram is printed to scale, so you can ei<strong>the</strong>rtransfer <strong>the</strong> measurements manually onto yourFigure 13-15Fold <strong>the</strong> tab to secure <strong>the</strong> motor.A screw secures <strong>the</strong> motor in <strong>the</strong> cage.sheet of plastic, using a marker rule and set-square,or you can photocopy this page and use it to markdirectly onto <strong>the</strong> plastic.Now mark out <strong>the</strong> plastic, and it should looklike Figure 13-17.The best way to cut corrugated plastic is to usea sharp craft knife and a cutting board. Becausesome of <strong>the</strong> cuts are internal, a pair of scissors willnot really be suitable. You will see that rectangles ofmaterial will need to be removed from <strong>the</strong> board—this is to provide space <strong>for</strong> our wheels. Do this firstas this is <strong>the</strong> easiest step. Now, see <strong>the</strong> littlerectangle which is off-center. Cut through bothlayers of plastic, and remove this piece of plasticfrom <strong>the</strong> board—this is waste and can be discarded.Now, with <strong>the</strong> “H” shape in <strong>the</strong> centre, we needto be careful. We are not removing this piece ofplastic, but we do need to bend it in order tosupport our fuel cell. Cut through both layers of<strong>the</strong> “H” marked in bold.Now, one of <strong>the</strong> properties of corrugated plasticis that if we want to make nice, clean folds,we can cut through one layer of plastic, but leave<strong>the</strong> o<strong>the</strong>r. So, along <strong>the</strong> dotted lines, carefully useyour craft knife to cut through one side of <strong>the</strong>plastic but not <strong>the</strong> o<strong>the</strong>r.Once all <strong>the</strong> excess plastic has been removed, <strong>the</strong>final blank chassis should look like Figure 13-19.The first step is to screw <strong>the</strong> motor and itsmounting to <strong>the</strong> board. If you transferred all <strong>the</strong>measurements, you should see four small crosses.These are <strong>the</strong> center-points where we will locate<strong>the</strong> screws to hold our motor mount down. Thesmall self-tapping screws bit readily into <strong>the</strong>plastic, and do not need any predrilling or centerpunching. You need to locate <strong>the</strong> motor, so that <strong>the</strong>shaft is hovering over <strong>the</strong> slot which we cut all <strong>the</strong>way through, as shown in Figure 13-20.Now, we need to select some appropriate gearing<strong>for</strong> our vehicle. A compromise will have to be madehere. Our motor provides a certain amount of“torque”, that is to say, “turning <strong>for</strong>ce,” and with afixed amount of power, it will run at a certain speed.P r o j e c t 3 3 : B u i l d i n g a S i m p l e F u e l C e l l C a r147
Figure 13-16Cutting diagram <strong>for</strong> <strong>the</strong> chassis.
Figure 13-17<strong>for</strong> cutting.The plastic chassis marked out readyWe want to optimize <strong>the</strong> relationship between speedand torque when transferring <strong>the</strong> power of <strong>the</strong> motorto <strong>the</strong> wheels on <strong>the</strong> ground. We can use gear ratiosto take <strong>the</strong> speed of <strong>the</strong> motor, and reduce <strong>the</strong> speed,but improve <strong>the</strong> torque. This gives our vehiclepulling power. However, remember, we trade torque<strong>for</strong> speed. Make <strong>the</strong> vehicle too powerful, and it willonly go very slowly. Make <strong>the</strong> vehicle too fast, andit may not have sufficient power to climb even <strong>the</strong>slightest incline, or navigate a rough surface. Inaddition, we can use compound gear ratios. We willnot be using <strong>the</strong>m in this model; however, it issomething you should be aware of. We can usegears to turn gears in effect, reducing or increasing<strong>the</strong> ratio each time.If a shaft spins at a set speed and it has a gearwith 10 teeth on <strong>the</strong> end, this gear with ten teethFigure 13-19The plastic chassis cut-out.<strong>the</strong>n engages with a gear with 60 teeth—<strong>the</strong> outputspeed will be one sixth of <strong>the</strong> original speed, but<strong>the</strong> turning <strong>for</strong>ce will be six times higher. We cansee how speed and power will be affected simplyby counting <strong>the</strong> teeth on <strong>the</strong> gears, and comparing<strong>the</strong> ratios. We can see some different arrangementsof gears in Figure 13-21.Your first fuel cell car is going to have simplegearing—a small spur gear driving a larger gearwhich will drive <strong>the</strong> axle which powers <strong>the</strong> wheels.Select <strong>the</strong> smallest gear from <strong>the</strong> assortment—<strong>the</strong>P r o j e c t 3 3 : B u i l d i n g a S i m p l e F u e l C e l l C a rFigure 13-18 Use a sharp craft knife to cut throughboth layers of <strong>the</strong> plastic.Figure 13-20gear-slot.Motor mounted with shaft above149
P r o j e c t 3 3 : B u i l d i n g a S i m p l e F u e l C e l l C a rFigure 13-21Combine <strong>the</strong> gears to make different ratios.one with <strong>the</strong> least teeth, and push it onto <strong>the</strong> shaftof <strong>the</strong> motor, as shown in Figure 13-22.Now, we are going to install <strong>the</strong> fuel cell—remember, we cut <strong>the</strong> board on one side of <strong>the</strong>“H”. . . well, fold <strong>the</strong> flaps up to provide support<strong>for</strong> <strong>the</strong> fuel cell, as shown in Figure 13-23.Now, you can ei<strong>the</strong>r use a little sticky tape, oreven some double-sided tape on <strong>the</strong> flaps, in orderto fix your fuel cell in place, like <strong>the</strong> image inFigure 13-24. The hole is <strong>the</strong> correct size <strong>for</strong> you towedge <strong>the</strong> fuel cell into place, with <strong>the</strong> holegripping around <strong>the</strong> bottom of <strong>the</strong> cell providingadditional support.Next, we are going to mount <strong>the</strong> rear axle andgear wheel. Take one of <strong>the</strong> medium-sized singlegears, and hold it in <strong>the</strong> rectangular slot. Thecorrect-sized gear will allow <strong>the</strong> hole through <strong>the</strong>gear to align with one of <strong>the</strong> rectangular channelsin <strong>the</strong> corrugated plastic, as shown in Figure 13-25.Figure 13-22 The smallest gear should be a push-fiton <strong>the</strong> motor shaft.You may find that <strong>the</strong> axle supplied is a little tootight <strong>for</strong> <strong>the</strong> gear, so in this instance we can use asmall drill to enlarge <strong>the</strong> hole to a suitable size <strong>for</strong><strong>the</strong> axle.Next, push <strong>the</strong> axle down <strong>the</strong> channel, through<strong>the</strong> hole in <strong>the</strong> gear, and onto <strong>the</strong> o<strong>the</strong>r side of <strong>the</strong>plastic, and out <strong>the</strong> o<strong>the</strong>r side. It should looksomething like Figure 13-27.Now <strong>for</strong> attaching <strong>the</strong> wheels. First start with <strong>the</strong>front wheels. Again, you may find that you need todrill out <strong>the</strong> wheels slightly. Ano<strong>the</strong>r labor-savingway to make things fit is to heat <strong>the</strong> plastic tosoften it, allowing <strong>the</strong> axle to slide in. The way todo this is to heat <strong>the</strong> axle till it is hot, and push itinto <strong>the</strong> plastic wheel. This will cool to make avery firm fit. Make sure you heat <strong>the</strong> axle and pushFigure 13-23Fold <strong>the</strong> fuel cell support flaps up.150
Figure 13-24<strong>Fuel</strong> cell mounted in position.it into <strong>the</strong> wheel, not vice versa, <strong>for</strong> a good result.See Figure 13-28 <strong>for</strong> comparison.Once all of <strong>the</strong> wheels are attached, connect <strong>the</strong>motor to <strong>the</strong> terminals of <strong>the</strong> fuel cell, and usingshort lengths of hosing, connect <strong>the</strong> fuel cell to <strong>the</strong>Figure 13-26hole.Figure 13-27Use a small drill to enlarge <strong>the</strong> axleAxle and large gear wheel installed.P r o j e c t 3 3 : B u i l d i n g a S i m p l e F u e l C e l l C a rFigure 13-25plastic holes.Align <strong>the</strong> axle hole with <strong>the</strong> corrugatedFigure 13-28Heat <strong>the</strong> axle not <strong>the</strong> wheel.151
Project 34: Building an “Intelligent” <strong>Fuel</strong> <strong>Cell</strong> CarFigure 13-29(front view).Simple fuel cell car completerespective hydrogen and oxygen tanks, being sureto put a small plug in any unused ports in <strong>the</strong> fuelcell. You will find that a small piece of doublesidedtape or sticky tape will be sufficient toanchor <strong>the</strong> storage tanks in <strong>the</strong>ir correct position.●Figure 13-30Simple fuel cell car complete (side view).And <strong>the</strong>re you have it! Our completed fuel cellcar! See Figures 13-29 and 13-30 <strong>for</strong> how <strong>the</strong>finished model should look.You will now need to follow <strong>the</strong> procedure <strong>for</strong>charging <strong>the</strong> fuel cell with distilled water, and filling<strong>the</strong> tanks, <strong>the</strong>n creating hydrogen and oxygen usingelectrolysis. You will <strong>the</strong>n generate sufficienthydrogen to run <strong>the</strong> car <strong>for</strong> a small distance.Project 34: Building an “Intelligent” <strong>Fuel</strong> <strong>Cell</strong> CarIntelligent fuel cell lab (<strong>Fuel</strong> <strong>Cell</strong> StorePart No. 550190)If you just want a fuel cell car that you can playand experiment with out of <strong>the</strong> box, <strong>the</strong>n <strong>the</strong>intelligent fuel cell car is just <strong>the</strong> ticket! It providesa ready-made chassis, and it has a clever differentialgearbox and steering system, which allows <strong>the</strong> carto change direction when it bumps into obstacles.Take some foamboard, make a small enclosure withwalls 4 in-high, and your intelligent fuel cell carwill happily trundle around crashing into walls, and<strong>the</strong>n reversing in a different direction.Get <strong>the</strong> components <strong>for</strong> <strong>the</strong> car out of <strong>the</strong> box(Figure 13-31a), and <strong>the</strong>y should look like Figure13-31b.152
Figure 13-31aFigure 13-31bIntelligent fuel cell car in <strong>the</strong> box.Intelligent fuel cell car components.The first step is to press <strong>the</strong> wheels onto <strong>the</strong> stubsprotruding from <strong>the</strong> plastic chassis—your car will looklike Figure 13-33. None of <strong>the</strong> wheels are “driven”—<strong>the</strong> action takes place in <strong>the</strong> little black box in <strong>the</strong>center of <strong>the</strong> car, which provides all <strong>the</strong> power.Next, connect up your tanks to <strong>the</strong> fuel cell—you should be used to this procedure by now!The chassis comes with a special area to clip <strong>the</strong>tanks and <strong>the</strong> fuel cell to it. Install <strong>the</strong>m now.You’re likely to have a little bit of distilled watersplashing about, so install <strong>the</strong> cover over <strong>the</strong> motormechanism to prevent it from getting wet, as shownin Figure 13-35.Now, a handy plug is provided to charge <strong>the</strong> carfrom <strong>the</strong> supplied battery pack. When you areusing <strong>the</strong> PEM fuel cell in <strong>the</strong> electrolyzer mode,you will need to connect <strong>the</strong> leads from <strong>the</strong> plugto <strong>the</strong> fuel cell, as shown in Figure 13-36.However, when you want <strong>the</strong> car to “go,” youwill need to connect <strong>the</strong> motor unit to <strong>the</strong> fuel cell,as shown in Figure 13-37.And that’s everything complete! Ladies andgentlemen . . . The intelligent fuel cell car is inFigure 13-38.Project 34: Building an “Intelligent” <strong>Fuel</strong> <strong>Cell</strong> C a r153
Project 34: Building an “Intelligent” <strong>Fuel</strong> <strong>Cell</strong> CarFigure 13-32Figure 13-33Wheels installed.<strong>Fuel</strong> cells and tanks plumbing.Figure 13-34Figure 13-35<strong>Fuel</strong> cells and tanks installed.Splash cover installed over <strong>the</strong> motor.154
Figure 13-36Figure 13-38<strong>Fuel</strong> cell connected to <strong>the</strong> battery slot.The complete “intelligent” fuel cell car.Figure 13-37<strong>Fuel</strong> cell connected to <strong>the</strong> motor.Project 34: Building an “Intelligent” <strong>Fuel</strong> <strong>Cell</strong> C a r155
Project 35: Building a Hydride-Powered <strong>Fuel</strong> <strong>Cell</strong> Vehicle●●●Simple or intelligent fuel cell car (see above)H-Gen hydrogen generatorSodium borohydrideProject 35: Building a Hydride-Powered<strong>Fuel</strong> <strong>Cell</strong> VehicleAno<strong>the</strong>r approach that has been investigated <strong>for</strong>fuel cell vehicles is to use hydrides <strong>for</strong> storinghydrogen. This has <strong>the</strong> advantage that hydrides areeasier to store than hydrogen gas; however, <strong>the</strong>re isan associated weight penalty.It has been speculated that vehicles could be“fueled” with a hydride, which is re<strong>for</strong>med onboard<strong>the</strong> vehicle using a catalyst. Once <strong>the</strong> catalystexhausts <strong>the</strong> supply of hydrogen from <strong>the</strong> hydride,<strong>the</strong> spent fuel is returned to a holding tank. Thisspent fuel could <strong>the</strong>n be offloaded from <strong>the</strong> vehicleat a filling station, and regenerated chemically toits previous state, ready <strong>for</strong> <strong>the</strong> next customer. Thehydrogen would have to be separated from <strong>the</strong>liquid hydride, <strong>the</strong>n any heat produced from <strong>the</strong>re<strong>for</strong>ming process would be extracted using a heatexchanger, with <strong>the</strong> hydrogen being fed to a fuelcell to produce electrical power, which would <strong>the</strong>npower electric motors. A schematic of this processis shown in Figure 13-39.Remember <strong>the</strong> H-Gen that we used in <strong>the</strong>chapter on storing hydrogen (Chapter 4)? Well,let’s try powering our fuel cell vehicle fromhydrides!Produce hydrogen and oxygen as you normallywould by electrolysis. Save <strong>the</strong> oxygen in <strong>the</strong>storage tank but open <strong>the</strong> hydrogen tank, andallow it to vent so <strong>the</strong>re is no hydrogen gas. Now,put a little sodium borohydride in <strong>the</strong> distilledwater, and drop <strong>the</strong> catalyst pill from <strong>the</strong> H-Geninto <strong>the</strong> water. As hydrogen is produced, hold <strong>the</strong>storage part of <strong>the</strong> gas cylinder over <strong>the</strong> fizzingpill to capture hydrogen. Wait as a little hydrogenbuilds up under <strong>the</strong> cap, and <strong>the</strong>n press itfirmly home.You should be able to power your fuel cellvehicle from <strong>the</strong> hydrogen, which is being releasedfrom <strong>the</strong> hydride.The limiting factor is now <strong>the</strong> fuel cell’s supply ofoxygen. As we have seen, fuel cells can functionon air, but <strong>the</strong> per<strong>for</strong>mance is likely to be fairlypoor, and your fuel cell may not produce enoughpower to move your vehicle.Figure 13-39Schematic of hydride vehicle.156
●●●●●●●●●Project 36: Building a Radio-Controlled <strong>Fuel</strong> <strong>Cell</strong> VehicleA radio-controlled carPEM fuel cell (<strong>the</strong> type used in <strong>the</strong> last twoexperiments is suitable)Hydrogen storage tankOxygen storage tankDC-DC convertorShort lengths of wireSmall piece of corrugated plastic, correx,or corrofluteDouble-sided tapeElectrician’s screwdriverWhen choosing a radio-controlled vehicle, youneed to look <strong>for</strong> something small that will run on4.5 V—larger radio-controlled vehicles require alot of juice, and have large battery packs—oursmall fuel cell will wimp out at <strong>the</strong> sight of <strong>the</strong>m,so look <strong>for</strong> something a little more modest thatruns from ei<strong>the</strong>r AA or AAA batteries.In this project, we are going to convert a radiocontrolled(RC) car to run on fuel cell power!We are going to take an off-<strong>the</strong>-shelf car andsoup it up, to run it from clean, green hydrogenpower.We can’t simply connect our fuel cell directly.The reason <strong>for</strong> this is that <strong>the</strong> motors we used in<strong>the</strong> previous two projects were small low-voltagemotors. They are quite happy to run from <strong>the</strong>low voltage produced by a single-cell fuel cell;however, <strong>the</strong> needs of even a small RC car are alittle more demanding. We are going to boost <strong>the</strong>voltage using a DC-DC converter. Remember <strong>the</strong>characteristics of fuel cells that we discovered?They tend to produce a fair amount of current, but<strong>the</strong> cell voltage is <strong>the</strong> limitation. Well, a DC-DCconverter helps us get around this limitation bysacrificing current <strong>for</strong> voltage. We are going to usea small DC-DC convertor to boost <strong>the</strong> single-cellpower of our fuel cell up to a voltage suitable <strong>for</strong>powering a little RC car.When you have selected your vehicle, assembleall your components, and you should havesomething that looks a little like Figure 13-40.Now, it must feel like Christmas come early—open<strong>the</strong> box of your RC car, and take out <strong>the</strong> car. Thehandset controller will be powered by ordinarybatteries, so now would be a good time to fit some.The battery compartment of your RC car willmost likely have a screw to secure it, so take asmall screwdriver, remove <strong>the</strong> screw and open up<strong>the</strong> battery compartment of your RC car.I recommend that you use solid wire <strong>for</strong>attachment ra<strong>the</strong>r than flexible wire—<strong>the</strong>re are acouple of reasons <strong>for</strong> this—it makes <strong>the</strong> next stepeasier, and fur<strong>the</strong>rmore, it allows you to “bendyour wire to shape,” making sure that it doesn’tsnag <strong>the</strong> wheels of your RC vehicle.Project 36: Building a Radio-Controlled <strong>Fuel</strong> <strong>Cell</strong> Vehicle157
Project 36: Building a Radio-Controlled <strong>Fuel</strong> <strong>Cell</strong> VehicleFigure 13-40Figure 13-41Components <strong>for</strong> RC fuel cell car.RC car and handset.You need to locate <strong>the</strong> two single terminals.One will be a spring (this is <strong>the</strong> negative) while <strong>the</strong>o<strong>the</strong>r will be a flat plate (<strong>the</strong> positive)—<strong>the</strong>polarity and way that <strong>the</strong> batteries are insertedshould be clearly labeled inside <strong>the</strong> compartment.Ignore <strong>the</strong> double terminals—<strong>the</strong>se are just used tomake a contact path between <strong>the</strong> batteries. Thedotted white line shows <strong>the</strong> path that <strong>the</strong> electricitywould normally flow between <strong>the</strong> batteries.We are going to be “piggy backing” onto <strong>the</strong>battery terminals—if you are only going to use <strong>the</strong>car <strong>for</strong> this project, <strong>the</strong>n you might consider apermanent method of attachment. As a rule, it willbe hard to solder wires onto your battery contactsif <strong>the</strong>y are made of stainless steel, so you mightlook at conductive glues which do a similar job tosolder, but without <strong>the</strong> heat (and <strong>the</strong>y take a littlelonger to cure).The method which I have found is best <strong>for</strong>attaching wires is to use a very fine electrician’sscrewdriver and lever <strong>the</strong> battery terminal <strong>for</strong>ward158
Figure 13-42labeled.RC car battery compartment—terminalsa little, <strong>the</strong>n try and slide <strong>the</strong> solid core wire in <strong>the</strong>space between <strong>the</strong> terminal and <strong>the</strong> plastic of <strong>the</strong>car body. This will be a tight fit, and should besufficient to reliably hold <strong>the</strong> wire in place.Once you have made a good electrical contact,shut and screw back <strong>the</strong> battery compartment,trapping your wire in <strong>the</strong> space between <strong>the</strong> batteryflap and door. (If <strong>the</strong> worst comes to <strong>the</strong> worst, andyou can’t find a way out <strong>for</strong> your wires, you couldalways use a small needle file to file a smallgroove to allow your wires to pass through.)Figure 13-43 Underside of <strong>the</strong> RC car with wiresleading to <strong>the</strong> battery compartment.You could always check <strong>for</strong> a good contact nowusing a wall-wart power supply (but make sureit’s set to <strong>the</strong> right polarity, or else you will fry<strong>the</strong> electronics of your vehicle.) It’s probablyeasier to do this now as a fault-finding exercisethan to wait until everything is assembled.Now flip <strong>the</strong> car over, and you should end upwith something like Figure 13-44.Now, to power our little automotive beastie,we are going to need <strong>the</strong> previously mentionedDC-DC converter. If you want to take <strong>the</strong> hassleout of things, you can just buy a little boardoff-<strong>the</strong>-shelf (<strong>the</strong> <strong>Fuel</strong> <strong>Cell</strong> Store do one—partnumber listed above). However, if you’re adab hand with <strong>the</strong> soldering iron, look atFigure 13-45 to see how you can make yourown.Figure 13-44RC car with power wires.Project 36: Building a Radio-Controlled <strong>Fuel</strong> <strong>Cell</strong> Vehicle159
Project 36: Building a Radio-Controlled <strong>Fuel</strong> <strong>Cell</strong> VehicleFigure 13-45If you have some skill with hobby electronics, a DC-DC converter board is very easy to make, as anintegrated circuit removes many discrete components.You will see, ei<strong>the</strong>r on <strong>the</strong> schematic or <strong>the</strong>PCB, depending on what option you have selected,that <strong>the</strong>re is very clearly an IN and an OUT.The DC-DC converter is polarity sensitive, somake sure that you get things <strong>the</strong> right way round!It should seem fairly obvious that <strong>the</strong> OUT endconnects to <strong>the</strong> wires coming from under ourRC car, while <strong>the</strong> IN end leads to <strong>the</strong> fuel cell.In <strong>the</strong> shop bought board, you just need to take anelectrician’s screwdriver, and secure <strong>the</strong> strippedends of <strong>the</strong> wire in <strong>the</strong>ir terminal blocks.Figure 13-46DC-DC converter board schematic.DC-DC converter board from <strong>the</strong> <strong>Fuel</strong> <strong>Cell</strong> Store.Car roofs tend to be curvy streamlined affairs—great <strong>for</strong> aerodynamics in <strong>the</strong> real world at highspeed, but not a good surface <strong>for</strong> mounting fuelcells! We, however, are going to take a small sheetof corrugated plastic—lightweight and strong—anduse it at a plat<strong>for</strong>m <strong>for</strong> affixing our components.First of all, we are going to cover it in doublesidedtape, on both sides, in order to provide asticky surface to easily mount our components.The beauty of using double-sided tape is that astrong tape should provide sufficient mechanical160
Cover <strong>the</strong> plastic plat<strong>for</strong>m with double-Figure 13-47sided tape.support <strong>for</strong> all <strong>the</strong> components while you experiment,but is weak enough that should you wish touse <strong>the</strong> components (and <strong>the</strong> RC car) again, youcan easily disassemble <strong>the</strong>m with a little care—and<strong>the</strong>y won’t be damaged.Now we come to <strong>the</strong> powerhouse <strong>for</strong> our teenymotor! Remove <strong>the</strong> backing from <strong>the</strong> double-sidedtape, and position your hydrogen tank, oxygentank, and fuel cell on <strong>the</strong> sticky surface. This willhold everything in place. Now, remove <strong>the</strong> backingFigure 13-48The hydrogen fuel cell power unit.from <strong>the</strong> double-sided tape on <strong>the</strong> opposite site of<strong>the</strong> plastic, and stick <strong>the</strong> assembly on <strong>the</strong> roof ofyour car. Now, taking <strong>the</strong> tubes, connect upyour fuel cell to <strong>the</strong> tanks—you should know <strong>the</strong>drill by now!Once you have connected up <strong>the</strong> DC-DCinverter, fuel cell, and car battery terminals, youcan think about mounting <strong>the</strong> equipment on yourvehicle. Double-sided tape is relatively easy touse, and generally won’t damage <strong>the</strong> vehicleunderneath if you want to change things around.For mounting <strong>the</strong> DC-DC convertor, you couldemploy a similar approach, or alternatively youcould mount it using Blu-Tack.Make sure that <strong>the</strong> wires are kept out of <strong>the</strong> wayfrom any wheels so that <strong>the</strong>y do not snag.The finished vehicle is shown in Figures 13-49and 13-50—it’s not going to win any awards <strong>for</strong>automotive design brilliance, but it is certainly oneof <strong>the</strong> greenest cars on <strong>the</strong> block.If you wanted to get more advanced, you couldconsider removing <strong>the</strong> vehicle components from itsenclosure and constructing a new body, but this ispurely an aes<strong>the</strong>tic issue—<strong>the</strong> function of <strong>the</strong> carwill remain <strong>the</strong> same! If you do decide to go downthis route, you will be confronted by similar issuesProject 36: Building a Radio-Controlled <strong>Fuel</strong> <strong>Cell</strong> Vehicle161
Project 36: Building a Radio-Controlled <strong>Fuel</strong> <strong>Cell</strong> VehicleFigure 13-49(top view).The completed RC fuel cell carto <strong>the</strong> major automotive manufacturers—whereto mount <strong>the</strong> hydrogen storage tanks, which aresomewhat big and bulky.Once your vehicle is complete, follow <strong>the</strong>procedures in <strong>the</strong> PEM fuel cell chapter (Chapter 7)<strong>for</strong> charging your fuel cell with distilled water,producing hydrogen by electrolysis, and <strong>the</strong>nconnect <strong>the</strong> DC-DC convertor back <strong>for</strong> somerip-roaring racing action!You could consider building an obstacle course<strong>for</strong> your car and seeing how well it per<strong>for</strong>ms.Remember, <strong>the</strong> challenge isn’t just to stay on <strong>the</strong>road, but also to stop distilled water from sloppingout of <strong>the</strong> rooftop storage tanks, as <strong>the</strong>se areproviding <strong>the</strong> pressure <strong>for</strong> <strong>the</strong> hydrogen (andoxygen) underneath.You will find that your vehicle per<strong>for</strong>ms muchbetter on smooth surfaces. Small RC cars do notalways per<strong>for</strong>m very well on carpeted surfaces.Also, if you stick to tiled and laminated surfaces,it is easier to wipe up any distilled water that isspilt in a major collision!Figure 13-50 The completed RC fuel cell car(side view). Figure 13-51 Choose smooth surfaces, not carpet.162
<strong>Fuel</strong> cell planesAnd now, we move swiftly on from fuel cells on<strong>the</strong> road to fuel cells in <strong>the</strong> sky—we are going tohave a look at some of <strong>the</strong> different ways thathydrogen could be used in <strong>the</strong> future to transportus from place to place.At <strong>the</strong> moment, <strong>the</strong> aviation industry is growingat an unprecendented rate. It’s now possible to flycheaply and com<strong>for</strong>tably—a dream that only50 years ago was out of reach <strong>for</strong> many people.However, this boom in aviation and travel comesat a cost—a carbon cost. Airplanes produce vastquantities of carbon dioxide, as <strong>the</strong>ir jet enginesooze out <strong>the</strong> emissions from burning hydrocarbonkerosene. If we are to look to a future beyond oil,we need to look at o<strong>the</strong>r alternatives that canparachute us into <strong>the</strong> 21st century.Using hydrogen in <strong>the</strong> air isn’t a new phenomenon.The Russian airplane company, Tupolev, successfullyflew a tri-jet airliner in 1988 in <strong>the</strong> <strong>for</strong>mer SovietUnion, where one of <strong>the</strong> engines was powered byhydrogen that was stored onboard cryogenically.The aircraft was a Tu154 airliner that had beenspecially adapted.Hydrogen is a fuel that is well suited to use inaircraft due to its tremendous energy—by weight;however, as a result of its poor energy density byvolume, it is apparent that future aircraft fueledby hydrogen will require tanks that are four timesbigger than those employed on current aircraft.NASA introduced fuel cells to flying with itsHelios prototype unmanned plane. The plane couldprovide a substitute <strong>for</strong> expensive satellites, byorbiting <strong>the</strong> earth, unmanned, powered by clean,green energy from <strong>the</strong> sun during <strong>the</strong> day, its largewing structure being covered in photovoltaic cells,while producing hydrogen from spare power. Then,during <strong>the</strong> night when <strong>the</strong> sun is hidden away, <strong>the</strong>reserves of hydrogen generated during <strong>the</strong> day areconverted to electrical energy to drive <strong>the</strong> plane’spropellers and maintain flight during <strong>the</strong> night.<strong>Fuel</strong> <strong>Cell</strong> PlanesFigure 13-52NASA Helios prototype. Image courtesy NASA.163
A little later in this chapter, we are going to lookat lighter-than-air travel, but next, let’s blast offinto outer space!P r o j e c t 3 7 : S p a c e T r a v e l w i t h H y d r o g e n !●●Manganese (IV) oxideZinc scraps● Hydrochloric acid (4.0 mol l −1 )● Hydrogen peroxide (3%)●●●●●●●●●●If you want to read some more abouthydrogen-powered planes, <strong>the</strong> following area good selection of Web links:www.flug-revue.rotor.com/FRheft/FRH9809/FR9809k.htmwww.bl.uk/collections/patents/greenaircraft.htmlwww.nasa.gov/centers/dryden/history/pastprojects/Erast/helios.html2 × boiling tubes2 × rubber bungsorPEM electrolyzerPower sourceGlovesandSafety specsMicrobore tubingCork lidPaperclipPlastic pastettesProject 37: Space Travel with Hydrogen!Building a Hydrogen Rocket●●Tesla coilAwlYou’ve seen how metal scraps and acid can beused to produce hydrogen—well, in thisexperiment, we are also going to use manganeseoxide and hydrogen peroxide to produce oxygen.Alternatively, if you haven’t got that sort of stuffhanging around, you can produce hydrogen andoxygen using your PEM electrolyzer.If you aren’t sure where to get a Tesla coil from,talk to a good science lab technician at a schoolor college, or check out Bob Iannini’s ElectronicGadgets <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>, McGraw-Hill, 2004,which comes with some fab ideas <strong>for</strong>high-voltage electric-spark-making mayhem!164
Making a suitable bungYou will need to take a rubber bung that fitsyour boiling tubes, and drill a small hole init using an awl or a small drill, through whichyou can insert some microbore nylon tubing.You will use this bung to help you collect <strong>the</strong>gases generated by <strong>the</strong> chemical reactions.Alternatively, if you are using your PEMelectrolyzer, you will need some microbore tube“epoxied” into <strong>the</strong> end of <strong>the</strong> standard rubbertubing, in order to squeeze <strong>the</strong> tube into <strong>the</strong>opening of <strong>the</strong> pastette.Producing hydrogenTake a clean boiling tube, and drop in a couple ofsmall pieces of zinc and a little 4.0 mol l −1 ofhydrochloric acid, so that <strong>the</strong>re is about twoinches of fluid in <strong>the</strong> tube. The hydrogen gaswill bubble. Using a similar bung to that describedabove, you will be able to displace some of <strong>the</strong>water in <strong>the</strong> pastette.Producing oxygenOn <strong>the</strong> tip of <strong>the</strong> spatula, take a small quantityof manganese (IV) oxide and place it ina boiling tube. Now add 3% hydrogen peroxide.You should have about 2 inches or so offluid in <strong>the</strong> bottom of <strong>the</strong> tube. Now quicklystopper <strong>the</strong> tube with a bung—it will havea small length of tube attached. Insert <strong>the</strong>tube into <strong>the</strong> pastette.Preparing <strong>for</strong> launchUsing <strong>the</strong> two boiling tubes full of hydrogen andoxygen, fill a small pastette half with hydrogenand half with oxygen. Leave about an inch ofwater in <strong>the</strong> bottom. This helps to seal <strong>the</strong> gasesinside <strong>the</strong> tube, and fur<strong>the</strong>rmore provides a reactionmass to produce some meaningful thrust.Launching <strong>the</strong> hydrogen-fueledrocketHold <strong>the</strong> sparking end of <strong>the</strong> Tesla coil near to <strong>the</strong>base of <strong>the</strong> pastette where <strong>the</strong> gas meets <strong>the</strong> water.After several sparks, you will hear a loud pop, andyour pastette will fly off <strong>the</strong> end of <strong>the</strong> paperclip,soaring into <strong>the</strong> sunset . . . well, not quite! At leastover <strong>the</strong> o<strong>the</strong>r side of <strong>the</strong> room!If all that seems like a little bit too much hardwork, Estes, <strong>the</strong> model rocket company, now sell ahydrogen rocket kit, where hydrogen produced by<strong>the</strong> process of electrolysis is used to launch a smallrocket from a launch pad. The solution comesready-made—with this book, you now understand<strong>the</strong> science!P r o j e c t 3 7 : S p a c e T r a v e l w i t h H y d r o g e n !Building a launch padYou need a small rod to launch yourhydrogen rocket, so take a small paperclip,straighten it out, and stick it into a largecork lid from a jar. The pipette can <strong>the</strong>nslide onto <strong>the</strong> rod.Figure 13-53Pipette hydrogen rocket.165
If you want to go beyond hydrogen, and exploremore aspects of amateur rocketry, check out mybook 50 Model Rocket <strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong><strong>Genius</strong>, McGraw-Hill, 2006.P r o j e c t 3 8 : A i r T r a v e l w i t h H y d r o g e n !Figure 13-54●●●●●●●<strong>Fuel</strong> cell mini-PEM (<strong>Fuel</strong> <strong>Cell</strong> Store P/N:531907)Small plastic propellerSmall, efficient motor (e.g., pager motor)Length of plastic tubingSheet of MylarMylar helium balloonHousehold ironEstes hydrogen rocket kit.Project 38: Air Travel with Hydrogen! Building aHydrogen-fueled AirshiporAs much as this experiment is about building anairship, it is also about learning as regards <strong>the</strong>density of hydrogen gas relative to air.We can produce hydrogen, using any of <strong>the</strong>methods in this book, to fill a sealed envelope oflightweight material. You could use an off-<strong>the</strong>-shelfhelium balloon, filled with hydrogen, or you couldmake your own envelope from Mylar which can beeasily heat-sealed with a household iron. Take atube from <strong>the</strong> balloon, and epoxy it to one of <strong>the</strong>mini fuel cells we encountered in Chapter 7. Thepower from this PEM fuel cell can be used to feeda small electric motor, which in turn can be used toturn a model toy propeller to create a moving (ifsomewhat erratic) blimp!You will find that, as hydrogen is consumed topower your motor, <strong>the</strong> blimp will gradually loseheight, so our blimp will only make short flights.But you can always recharge your blimp by166
Figure 13-55 A home filled, powered blimp froma standard helium balloon.making some more hydrogen with your PEM fuelcell, making sure to anchor <strong>the</strong> blimp down whenfilling it, so it doesn’t go drifting off.Helium balloons come with a handy hole andone-way valve <strong>for</strong> insertion of a nozzle; however,you will have to make sure, when fixing yourhydrogen supply pipe <strong>for</strong> your fuel cell that <strong>the</strong>If you want to take <strong>the</strong> last experiment fur<strong>the</strong>r,you might like to consider <strong>the</strong> possibility ofbuilding an airship that you can control and steerentry point of <strong>the</strong> pipe is well sealed to prevent <strong>the</strong>escape of hydrogen. A little dab of glue (or <strong>the</strong>ubiquitous duct tape) goes a long way to keepingthings snug.Remember, if you find that you are not gettingsufficient push from your propeller, try reversing<strong>the</strong> polarity of <strong>the</strong> motor and see what effectthat has.The fuel cell, motor, and propeller can all bemounted on <strong>the</strong> tail of <strong>the</strong> balloon, using a fewdabs of hot melt glue, or even tape.Compensate <strong>for</strong> <strong>the</strong> buoyancy of <strong>the</strong> hydrogenby adding a little plasticine or modelling clayto <strong>the</strong> bottom of <strong>the</strong> balloon.Helium is generally used as <strong>the</strong> gas of choice <strong>for</strong>filling balloons ra<strong>the</strong>r than hydrogen as it isnonflammable; however, hydrogen has morelifting power, at <strong>the</strong> expense of being slightlymore dangerous! If you are going to fly ahydrogen balloon, think very carefully about <strong>the</strong>areas you fly it in, and ensure that <strong>the</strong>re are nosources of ignition present.Project 39: Building a Radio-Controlled Airshipfrom base control using radio control. You will beusing hydrogen <strong>for</strong> its lifting power, and <strong>the</strong>actual motors will be powered by batteries in <strong>the</strong>P r o j e c t 3 9 : B u i l d i n g a R a d i o - C o n t r o l l e d A i r s h i p167
P r o j e c t 3 9 : B u i l d i n g a R a d i o - C o n t r o l l e d A i r s h i pradio control kits; however, you might like toconsider how a DC-DC convertor could be used topower some of <strong>the</strong> lower-powered kits. Also,remember, <strong>the</strong>se kits are designed to work withhelium, as it is generally seen as safer (it doesn’texplode). If you are going to use hydrogenin <strong>the</strong>se blimp kits, think very carefully aboutwhere you are going to fly <strong>the</strong>m, as you don’twant to be causing fireballs, do you? Make sureyou stay away from areas where <strong>the</strong>re could be anaked flame, or o<strong>the</strong>r source of ignition.www.johnjohn.co.uk/shop/html/model_radiocontrol_blimp.htmlwww.hobbytron.com/mach3_rc_blimp.htmlstore.makezine.com/ProductDetails.asp?ProductCode=MKBLIMPKIT168
Chapter 14More Fun with Hydrogen!In this chapter, we are going to explore somedifferent things that you can do with hydrogen—some of <strong>the</strong>se projects are good <strong>for</strong> demonstration,showing and proving that hydrogen has genuineapplications in <strong>the</strong> real world. These experimentsare presented more as an illustration of what canbe done than as practical objects to use every day;however, as <strong>the</strong> technology gains momentum,expect some of <strong>the</strong> ideas in this chapter to becomemainstream.Project 40: Powering a Radio Using Hydrogen●●●●●●●●●100 µF capacitor100 pF capacitor1mH inductor1N5819 diode274 K resistor (1% tolerance)100 K resistor (1% tolerance)100 µF capacitorUSB socketMAX 630 CPA integrated circuitYet ano<strong>the</strong>r application <strong>for</strong> our fabulous DC-DCconverter featured in <strong>the</strong> radio-controlledfuel cell car project—why not use a fuel cell radioto power some tunes? Imagine <strong>the</strong> scene—you’restuck on a remote island, with your fuel cellexperimenter’s kit, a solar panel, and an oldradio, but your favorite music is played attwo in <strong>the</strong> morning when it’s dark and <strong>the</strong>solar cell won’t work! Simple—use <strong>the</strong> fuel cellas a battery to store energy made during <strong>the</strong> day<strong>for</strong> use at night!You need to find a cheap radio, which takes twoor three AA or AAA batteries, i.e., its powersupply requirements are between 3 and 4.5 V. Startsmall, and look <strong>for</strong> a radio which has minimalpower consumption requirements, as this way, yourtiny store of hydrogen will last a little longer!The circuit diagram shown in Figure 14-1 is <strong>for</strong>our ubiquitous DC-DC converter, which takes ourlow-voltage power from <strong>the</strong> fuel cell, and trans<strong>for</strong>msit to a higher voltage output suitable <strong>for</strong> poweringelectrical devices—in this case, our radio.You are going to need to investigate <strong>the</strong> batterycompartment of your radio, and work out where toconnect <strong>the</strong> output from <strong>the</strong> DC-DC converter. Lookat <strong>the</strong> path that <strong>the</strong> circuit makes in <strong>the</strong> batterycompartment. It is usual to have a single metalplate covering one battery terminal <strong>for</strong> where <strong>the</strong>circuit connects to <strong>the</strong> battery pack, and a doubleplate which covers two adjacent battery terminals,where a connection is being made between batteries.The positive terminal will likely be a flat plate and<strong>the</strong> negative terminal will probably be a spring.While it may seem like folly to power aradio from an expensive fuel cell, electronicsmanufacturers are actually looking toward fuelcells to make <strong>the</strong> next generation of electronics169Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
P r o j e c t 4 0 : P o w e r i n g a R a d i o U s i n g H y d r o g e nFigure 14-1Figure 14-2Hydrogen-powered radio schematic.Hydrogen-powered radio connected up.devices which run <strong>for</strong> longer. There are limitationswith battery technology—batteries are fairlyheavy and bulky, and <strong>the</strong>y only last <strong>for</strong> a certainamount of time. So to get round <strong>the</strong>se limitations,manufacturers are looking at integrating fuel cellsinto mobile devices, along with replaceable “fuelcartridges” containing hydrogen or methanolacting as a hydrogen carrier.I’ve uploaded a short video of this setup toYouTube, which can be accessed at:www.youtube.com/watch?v=CRhM0ixrmRA170
●●●●●●●●●iPod Shuffle or similar USB MP3 playerHydrogen 100 µF capacitor100 pF capacitor1 mH inductor1N5819 diode274 K resistor (1% tolerance)100 K resistor (1% tolerance)100 µF capacitorUSB socketProject 41: Hydrogen-<strong>Fuel</strong>ing your iPod‘●●●MAX 630 CPA integrated circuitorDC-DC converter (preassembled) (<strong>Fuel</strong> <strong>Cell</strong> StorePart Number: 590709)Voller hydrogen generator (<strong>Fuel</strong> <strong>Cell</strong> Store PartNumber: 72035001)In this project, we are going to be using ourubiquitous DC-DC converter to power an iPod.Ra<strong>the</strong>r than hack <strong>the</strong> iPod and invalidate <strong>the</strong>warranty, we are going to get a USB PCB mountedsocket, and solder <strong>the</strong> power outputs from ourDC-DC converter. Ensure that you get <strong>the</strong> wiresaround <strong>the</strong> right way as iPods—as with o<strong>the</strong>r solidstate electrical devices—are polarity sensitive, andP r o j e c t 4 1 : H y d r o g e n - F u e l i n g y o u r i P o d ‘Figure 14-3Hydrogen-powered iPod diagram.171
P r o j e c t 4 2 : M a k i n g H y d r o g e n B u b b l e sFigure 14-4●●●●●BungThistle tubeErlenmeyer flask with side tapSwan neck tubeVoller hydrogen generator.if you get <strong>the</strong> wires <strong>the</strong> wrong way round, you willend up with friedTunes ra<strong>the</strong>r than iTunes.In this project, we are going to use an iPodshuffle, as <strong>the</strong>y are cheap and have a much lowercurrent draw than <strong>the</strong> larger hard-disk based iPods.There are a number of o<strong>the</strong>r USB MP3 players,and o<strong>the</strong>rs may work equally well; however, it isimpossible to obtain data on <strong>the</strong> power consumption<strong>for</strong> all devices.You will need to assemble <strong>the</strong> circuit as shownin <strong>the</strong> diagram, or purchase <strong>the</strong> ready-assembledprinted circuit board from <strong>the</strong> <strong>Fuel</strong> <strong>Cell</strong> Store.Acid (e.g., dilute hydrochloric acid)You will also need to purchase a USB socket,which is used to connect <strong>the</strong> MP3 player to <strong>the</strong>DC-DC converter. Again, refer to Figure 14-3, andensure that you connect <strong>the</strong> inverter to <strong>the</strong> socketwith <strong>the</strong> correct polarity, or else you risk damagingyour MP3 player.Ano<strong>the</strong>r option <strong>for</strong> powering your portableelectronics in remote places is <strong>the</strong> Voller hydrogengenerator (shown in Figure 14-4)—a fuel-cellbased generator, which runs on hydrogen, andwhich provides a USB power output, a 110 V or230 V (depending on <strong>the</strong> model) line power outputand a 12 V car accessory socket.The technology is currently out of <strong>the</strong> reach of<strong>the</strong> average consumer; however, <strong>for</strong> certain remoteapplications <strong>the</strong> cost is justified, and with advancesin fuel cell technology, expect to see <strong>the</strong> price dropsignificantly in <strong>the</strong> next several years.Many major electronics manufacturers are alsoinvestigating <strong>the</strong> possibility of including fuel celltechnology directly as part of <strong>the</strong>ir devices. In <strong>the</strong>next few years, you could be plugging a methanolcartridge into your laptop, portable media player,or mobile phone ra<strong>the</strong>r than a battery charger, toprovide long-life power <strong>for</strong> your electronicdevices, over and above that possible with presentbattery technologies.Project 42: Making Hydrogen Bubbles●●●Metal (e.g., magnesium ribbon)Washing-up liquid, detergent, or soap solutionBowlA fun experiment is to produce somehydrogen—in <strong>the</strong> example shown in Figure 14-5,we are using <strong>the</strong> acid-metal method to producehydrogen relatively quickly. As <strong>the</strong> hydrogen isproduced, and bubbles through <strong>the</strong> water in <strong>the</strong>bowl, <strong>the</strong> hydrogen will <strong>for</strong>m bubbles, which,172
Figure 14-5●●●Latex balloonsMatchesMaking hydrogen bubbles.being lighter than air, will float. These can <strong>the</strong>n beignited with a splint. It’s ano<strong>the</strong>r nice, quick andMethod of generating hydrogen and oxygen(discussed earlier in <strong>the</strong> book)Launching exploding hydrogen balloons into <strong>the</strong>air is a fun way of learning about <strong>the</strong> science of“stoichiometry.” Remember, chemical reactionswork best when <strong>the</strong> reactants are present in <strong>the</strong>correct quantities. The ideal mixture of hydrogento oxygen is 2:1—we learn this because <strong>the</strong> productof <strong>the</strong> complete combustion of hydrogen is H 2O.You can use <strong>the</strong> <strong>for</strong>mula <strong>for</strong> <strong>the</strong> volume of asphere, combined with measurements around <strong>the</strong>balloon’s circumference, to make rougheasy, fun experiment, which shows that hydrogenis lighter than air.Project 43: Exploding Some Hydrogen BalloonsFigure 14-6Exploding hydrogen balloons.P r o j e c t 4 3 : E x p l o d i n g S o m e H y d r o g e n B a l l o o n s173
P r o j e c t 4 4 : H a v i n g a H y d r o g e n B a r b e c u eapproximations of <strong>the</strong> volumes of gas you arefilling <strong>the</strong> balloons with.If we have too much hydrogen present, <strong>the</strong>nwhen <strong>the</strong> balloon is ignited, it will have to getoxygen from <strong>the</strong> surrounding air, providing less ofa bang. However, get <strong>the</strong> mixture of hydrogenand oxygen just right, and a very loud bang willensue.My <strong>for</strong>mer science teacher, Bob Spary, wouldrelease balloons filled with <strong>the</strong> correctmixture—and a long length of burning stringas a fuse over our school sports field, while <strong>the</strong>school soccer team practiced—and <strong>the</strong> ensuingbang never failed to make <strong>the</strong>m jump outof <strong>the</strong>ir skin!You might like to consider wearing a pair of eardefenders if you have sensitive ears, and, remember,● Hydro-Que (<strong>Fuel</strong> <strong>Cell</strong> Store P/N: 551005)●Source of hydrogenAs a conscious environmentalist, no doubtcarbon emissions will be your biggest concernwhen you go out back in <strong>the</strong> yard to have agrill—not whe<strong>the</strong>r <strong>the</strong> sausages are burnt or not!Burning gas in <strong>the</strong> garden is a source of carbonemissions. Patio heaters and gas grills are <strong>the</strong>enemy of <strong>the</strong> environmentalist, as <strong>the</strong>y are takingprecious fossil fuel resources and squandering<strong>the</strong>m needlessly.If you are burning wood, worry not if <strong>the</strong> woodcomes from a sustainably managed source, as youhowever you ignite <strong>the</strong> balloons, make sure youmaintain a safe distance!One possible method of “remote detonation” isto use a simple model rocket igniter taped to <strong>the</strong>balloon. If you want to read more about modelrocket igniter ignition systems, check out my book50 Model Rocket <strong>Projects</strong> <strong>for</strong> <strong>the</strong> <strong>Evil</strong> <strong>Genius</strong>,McGraw-Hill, 2006.If you want to watch exploding hydrogenballoons from <strong>the</strong> com<strong>for</strong>t of your armchair, take alook at <strong>the</strong> following cool YouTube videos:www.youtube.com/watch?v=7UoFNdp0UYgwww.youtube.com/watch?v=MMB2VR0087wwww.youtube.com/watch?v=p3LUHAr12qIwww.youtube.com/watch?v=kknU6cpKWL0www.youtube.com/watch?v=UUDy9heD6h8Project 44: Having a Hydrogen Barbecueare only putting <strong>the</strong> carbon dioxide back into <strong>the</strong>air that <strong>the</strong> tree consumed when it was growing.However, if you really want to bring your carbonemissions down to zero, consider having ahydrogen-fueled barbecue!Figure 14-7 The Hydro-Que hydrogen barbecue.Image courtesy <strong>Fuel</strong> <strong>Cell</strong> Store.174
Figure 14-8 Regulator valve and flash arrestor.Image courtesy <strong>Fuel</strong> <strong>Cell</strong> Store.The Hydro-Que is a barbecue grill especiallymodified to accept hydrogen gas as its fuelinput.Remember, at <strong>the</strong> moment, most hydrogen gasavailable commercially comes from fossil-fuelresources that are re<strong>for</strong>med by steam-cracking, soat <strong>the</strong> moment, <strong>the</strong> reduced environmental impactof having a hydrogen barbecue is more of asymbolic one than a practical one. However, wecan look <strong>for</strong>ward to <strong>the</strong> day when hydrogen isproduced by electrolysis using clean, renewableenergy. The Hydro-Que hydrogen barbecue ispictured in Figure 14-7.Note on <strong>the</strong> side of <strong>the</strong> Hydro-Que <strong>the</strong> gasregulator and flash arrestor. The regulator allowsyou to vary how much hydrogen is burned, andthus how much heat is produced by <strong>the</strong> barbecue.The flash arrestor prevents <strong>the</strong> flame fromtraveling back down <strong>the</strong> pipe and igniting <strong>the</strong>Figure 14-9barbecue.PURE Energy Centre hydrogenhydrogen upstream of <strong>the</strong> barbecue in <strong>the</strong> tankor hydride.So now you’ve eliminated all <strong>the</strong> carbonemissions from your barbecue, all you have got toworry about is <strong>the</strong> environmental impact of meatproduction!If you’re around in <strong>the</strong> Shetland Islands, checkout <strong>the</strong> PURE Energy Centre, where <strong>the</strong>y haveconverted a standard barbecue to run on hydrogenwith some clever pengineering—check out <strong>the</strong>irfuel cells, and pop by <strong>for</strong> a sausage!P r o j e c t 4 4 : H a v i n g a H y d r o g e n B a r b e c u e175
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Chapter 15<strong>Fuel</strong> <strong>Cell</strong> CompetitionsIf you are interested in taking some of <strong>the</strong> projects inthis book fur<strong>the</strong>r, <strong>the</strong>re are a number of competitionsworldwide open to young people. Competitions are agreat way to make use of your skills—hone andrefine <strong>the</strong>m, and receive recognition <strong>for</strong> things thatyou have learned. Throughout this book, I’ve flaggedup exciting projects which you might like to developfur<strong>the</strong>r <strong>for</strong> science fairs—ano<strong>the</strong>r great way ofshowcasing your knowledge and educating yourpeers about <strong>the</strong> hydrogen future.This chapter gives details of all <strong>the</strong> competitionsthat are accessible to young people at <strong>the</strong> time ofgoing to press; however, stay in touch with yourNational <strong>Fuel</strong> <strong>Cell</strong> Association, and keep your eyespeeled <strong>for</strong> more—as with growing awareness ofhydrogen and fuel cell science, <strong>the</strong>re are sure to benew competitions in <strong>the</strong> future!Contact details <strong>for</strong> <strong>the</strong> IYFCCKay Larson: Directorkay@iyfcc.comQuinn Larson: Student contact and travelquinn@iyfcc.comBridget Shannon: Sponsor contactbridget@iyfcc.comPhone: 303-237-3834Fax: 303-237-7810Address:PO Box 4038Boulder, CO 80306High school competitionsInternational Youth <strong>Fuel</strong> <strong>Cell</strong>Competition (IYFCC)The international youth fuel cell competition isopen to young people from around <strong>the</strong> world. Eachcountry is allowed to select up to three teams toenter <strong>the</strong> competition—a good starting point wouldbe to contact your National <strong>Fuel</strong> <strong>Cell</strong> Association,some addresses of which are listed in <strong>the</strong> back ofthis book, to find out about your national entryprocedure.The competition is open to students between <strong>the</strong>ages of 15 and 18, and an official team consists oftwo entrants.The great thing about this competition is that ittests your knowledge of fuel cells on so manylevels—<strong>the</strong>re is a <strong>the</strong>oretical element to <strong>the</strong>competition, in <strong>the</strong> <strong>for</strong>m of a “quiz bowl,” and<strong>the</strong>re are some practical, constructional challenges,where you can apply things that you have learnedin this book to build a fuel cell car, and a timepiecepowered by fuel cell.Go to <strong>the</strong> official IYFCC. website <strong>for</strong> fur<strong>the</strong>rin<strong>for</strong>mation: www.iyfcc.com177Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
F u e l C e l l C o m p e t i t i o n s<strong>Fuel</strong> cell car—things to thinkaboutThink about <strong>the</strong> power-to-weight ratio of yourvehicle—<strong>the</strong> power produced by <strong>the</strong> supplied fuelcell is fixed—you cannot change that! (But whatyou can do is ensure that your vehicle is as lightas possible!) Also consider <strong>the</strong> torque and speedproduced by your motor—match <strong>the</strong> poweravailable from your motor as closely as possiblewith <strong>the</strong> load, <strong>the</strong> wheels!<strong>Fuel</strong> cell timepiece—things tothink aboutThink back to <strong>the</strong> experiments where weproduced hydrogen using a PEM fuel cell as anelectrolyser, and when we took hydrogen andoxygen and converted <strong>the</strong>m using <strong>the</strong> fuel cellinto electrical power—what did you notice about<strong>the</strong> reaction when a fixed amount of power wasconsumed or produced? Was <strong>the</strong> gas producedat a steady rate or did it vary? Think about <strong>the</strong>properties of hydrogen—it is lighter than air.Could you trigger a physical action using <strong>the</strong>lightness of hydrogen gas once a given amounthas accumulated? Think about <strong>the</strong> airships in <strong>the</strong>chapter on hydrogen transport—think about <strong>the</strong><strong>for</strong>mula used to calculate how much hydrogen isrequired to lift a given weight. Think aboutelectrical power from a fuel cell—could that beused to trigger an action? How could you feedhydrogen to a fuel cell, once a given amount hasbeen produced by an electrolyzer?Car competition1. What components are we required to use on<strong>the</strong> car?You must use <strong>the</strong> fuel cell provided at <strong>the</strong>competition. It may have more power than <strong>the</strong> oneyou receive in <strong>the</strong> practice kit. You must replace <strong>the</strong>practice fuel cell with <strong>the</strong> new fuel cell at <strong>the</strong>competition. We do not recommend you travel onan airplane with <strong>the</strong> fuel cell unless you check it inchecked baggage. The motor will be <strong>the</strong> same oneprovided in <strong>the</strong> competition kit. You will haveaccess to a new motor at <strong>the</strong> competition, or youmay continue to use <strong>the</strong> one provided in <strong>the</strong>competition kit. You may use any o<strong>the</strong>r parts includedin <strong>the</strong> practice kit, but you are not required to do so.2. Are <strong>the</strong>re any prohibited items?You may not use hydrides or compressed hydrogenstorage. You may not use additional motors or fuelcells o<strong>the</strong>r than those required. If you are unsureabout a component, please contact Kay Larson <strong>for</strong>approval of questionable components (see <strong>the</strong>IYFCC Contact Details box).3. What are we allowed to bring with us?You may bring a car that is completely built.However, remember that you will need to replace <strong>the</strong>fuel cell and in doing so, you might need to makesome adjustments to your car at <strong>the</strong> competition.4. What will you provide <strong>for</strong> us to use to makeadjustments?There is a picture on <strong>the</strong> website that includes all of<strong>the</strong> tools and materials that will be available to youat <strong>the</strong> competition. Each team will have access toall of <strong>the</strong> tools and materials. Your car may becompletely built, and you might not need to use anyof <strong>the</strong> tools or materials. They are available <strong>for</strong> youin <strong>the</strong> event that you need to make major changes,or if you prefer to build your car at <strong>the</strong> competitionusing <strong>the</strong>se materials.5. How much time will we have to work on our carat <strong>the</strong> competition?You will have a work day, which is about eighthours. You can divide your time however youchoose between working on your car, yourtimepiece, or studying <strong>for</strong> <strong>the</strong> quiz bowl.Timepiece competition1. What components are we required to use on <strong>the</strong>timepiece?The only component you are required to use is <strong>the</strong>fuel cell you will receive at <strong>the</strong> competition.178
2. Are <strong>the</strong>re any prohibited items?You may not use anything that has a timing devicein it. The intent of <strong>the</strong> competition is that <strong>the</strong> use ofhydrogen production and/or storage must be <strong>the</strong>element that determines <strong>the</strong> length of time.3. What do you mean by “something must happen”at exactly two minutes?At two minutes, <strong>the</strong>re must be some noticeable andpredicted event. It could be that something happensat two minutes. It can also be that something stopshappening at two minutes.4. Can we use <strong>the</strong> fuel cell in electrolyzer modeonly if we want to <strong>for</strong> this competition?Yes, you can use <strong>the</strong> fuel cell just as an electrolyzermaking hydrogen in this competion.5. Can we make hydrogen be<strong>for</strong>e <strong>the</strong> two minutesbegin?Yes, you will have 10 minutes to prepare yourtimepiece be<strong>for</strong>e your timing begins. You mayuse as much of this time as you like to producehydrogen.6. How much of <strong>the</strong> timepiece can we build be<strong>for</strong>ewe come?You may bring a completed timepiece with you.Please remember that you will be required tochange <strong>the</strong> fuel cell to a new fuel cell at <strong>the</strong>competition, and this fuel cell may be morepowerful than <strong>the</strong> one in <strong>the</strong> practice kit. Beprepared to make adjustments.7. What will you provide <strong>for</strong> us to use to makeadjustments?There is a picture on <strong>the</strong> website that includes allof <strong>the</strong> tools and materials that will be available toyou at <strong>the</strong> competition. Each team will have accessto all of <strong>the</strong> tools and materials. Your car may becompletely built, and you might not need to use anyof <strong>the</strong> tools or materials. They are available <strong>for</strong> youin <strong>the</strong> event that you need to make major changes,or if you prefer to build your car at <strong>the</strong> competitionusing <strong>the</strong>se materials.8. How much time will we have to makeadjustments at <strong>the</strong> competition?You will have a work day, which is about eighthours. You may determine how much of this timeyou want to work on your timepiece, your car, orstudying <strong>for</strong> <strong>the</strong> Quiz Bowl.Rules and guidelines <strong>for</strong> <strong>the</strong>quiz bowlPurposeThe purpose of <strong>the</strong> International Youth <strong>Fuel</strong> <strong>Cell</strong>Competition Quiz Bowl is to encourage <strong>the</strong> studyof fuel cell technology, and to acknowledge <strong>the</strong>acceptance of scientific principles as a globaleducational standard.MatchesThe competition will consist of preliminary roundsand a final round. Teams in <strong>the</strong> final round will bedetermined by a double elimination tournament<strong>for</strong>mat. Teams will be chosen at random <strong>for</strong> <strong>the</strong>preliminary round of questioning, except thatteams from <strong>the</strong> same country will not competeagainst each o<strong>the</strong>r in <strong>the</strong> preliminary round. After<strong>the</strong> first round, teams from <strong>the</strong> same country maycompete against one ano<strong>the</strong>r.Rules <strong>for</strong> <strong>the</strong> quiz bowl1. Two types of questions will be used: toss-up andbonus questions. A toss-up question may beanswered by any member of ei<strong>the</strong>r team thatis playing. The toss-up question must be answeredcorrectly, in order <strong>for</strong> a team to be offereda bonus question.2. No team will have more than one opportunityto answer a toss-up question.3. Questions are ei<strong>the</strong>r multiple-choice or shortanswer. The only acceptable answer to amultiple-choice question is <strong>the</strong> one read by<strong>the</strong> moderator.4. Once read in its entirety, a question will not bereread.5. On toss-up questions, <strong>the</strong> first player on ei<strong>the</strong>r teamto activate <strong>the</strong> lock-out buzzer system wins <strong>the</strong> rightF u e l C e l l C o m p e t i t i o n s179
F u e l C e l l C o m p e t i t i o n sto answer <strong>the</strong> question. No player may buzz in untilafter <strong>the</strong> moderator has identified <strong>the</strong> subject areaof <strong>the</strong> question, e.g., physical science.6. Be<strong>for</strong>e answering <strong>the</strong> questions, <strong>the</strong> team membermust be verbally recognized by <strong>the</strong> moderatoror scientific judge. (Be<strong>for</strong>e <strong>the</strong> match, thisperson will be identified.) If not recognized,it is treated as a nonanswer and <strong>the</strong> moderatorwill not indicate whe<strong>the</strong>r <strong>the</strong> answer was rightor wrong.7. No consultation is allowed on toss-up questions.8. Should a player answer a toss-up question be<strong>for</strong>ebeing verbally recognized, or should consultationamong any of <strong>the</strong> team members occur, any answergiven does not count (<strong>the</strong> moderator does not saywhe<strong>the</strong>r <strong>the</strong> answer given was correct or incorrect),and <strong>the</strong> team loses <strong>the</strong> right to answer <strong>the</strong> toss-upquestion. The question is <strong>the</strong>n offered to <strong>the</strong>opposing team.9. On a toss-up question, <strong>the</strong> first answer given is <strong>the</strong>only one that counts. However, if a student givesboth a letter answer and a scientific answer, bothparts must be correct.10. If <strong>the</strong> answer to a toss-up question is wrong and <strong>the</strong>question was completely read, <strong>the</strong> o<strong>the</strong>r team isgiven <strong>the</strong> opportunity to answer <strong>the</strong> toss-upquestion, unless time expires be<strong>for</strong>e <strong>the</strong> secondteam has buzzed in. The second team is allowed afull 10 seconds to buzz in after <strong>the</strong> first team hasanswered incorrectly or has answered without beingrecognized, unless time expires.11. The answer to <strong>the</strong> bonus question must come from<strong>the</strong> team’s captain. Moderators should ignore ananswer from anyone but <strong>the</strong> captain on <strong>the</strong> bonusquestion.Timing rules12. The match is played until ei<strong>the</strong>r <strong>the</strong> time expires orall <strong>the</strong> toss-up questions have been read. Regionalcompetitions will have two 10-minute halves with atwo-minute break. Each half begins with a toss-upquestion.13. After reading a toss-up question, <strong>the</strong> moderator willallow 10 seconds <strong>for</strong> <strong>the</strong> two teams to respondbe<strong>for</strong>e proceeding to <strong>the</strong> next toss-up question.Timing begins after <strong>the</strong> moderator has completedreading <strong>the</strong> toss-up question.14. A student who has buzzed in on a toss-up questionmust answer <strong>the</strong> question promptly after beingverbally recognized by <strong>the</strong> moderator or scientificjudge. After recognizing a student, <strong>the</strong> moderatorwill allow <strong>for</strong> a natural pause (up to three seconds),but if <strong>the</strong> moderator determines that stallingoccurred, <strong>the</strong> team loses its opportunity to answer<strong>the</strong> question and it is offered to <strong>the</strong> opposing team,if eligible.15. After a team member has answered a toss-upquestion correctly, <strong>the</strong> team is given <strong>the</strong> opportunityto answer a bonus question. The team will have30 seconds to begin to give its answer to <strong>the</strong> bonusquestion. Consultation among team members isallowed on bonus questions.16. On a bonus question, <strong>the</strong> signal “5 SECONDS” willbe given by <strong>the</strong> timekeeper after 25 seconds of <strong>the</strong>allowed 30 seconds have expired. Additionally, <strong>the</strong>timekeeper will indicate <strong>the</strong> end of <strong>the</strong> 30-secondbonus period by saying “TIME.” If <strong>the</strong> team captainhas not begun <strong>the</strong> response be<strong>for</strong>e <strong>the</strong> timekeepercalls “TIME,” <strong>the</strong> answer does not count. If <strong>the</strong>team captain has begun <strong>the</strong> response, he or shemay complete <strong>the</strong> answer.Scoring17. Toss-up questions are worth four points, and bonusquestions are worth 10 points.18. If a toss-up question is interrupted, <strong>the</strong> studentrecognized, and <strong>the</strong> answer correct, <strong>the</strong> team willreceive four points. If <strong>the</strong> answer is incorrect, fourpoints are added to <strong>the</strong> opposing team’s score, <strong>the</strong>question is reread in its entirety, and <strong>the</strong> opposingteam has an opportunity to answer <strong>the</strong> toss-upquestion with <strong>the</strong> chance to answer <strong>the</strong> bonusquestion if correct.19. The double interrupt—if a toss-up question isinterrupted, <strong>the</strong> student has been verballyrecognized and <strong>the</strong> answer is incorrect, four pointsare added to <strong>the</strong> opposing team’s score. Thequestion is <strong>the</strong>n reread in its entirety. However,if a student on <strong>the</strong> opposing team interrupts <strong>the</strong>rereading of <strong>the</strong> question, <strong>the</strong> player is verbally180
ecognized and gives an incorrect answer. Fourpoints are added to <strong>the</strong> o<strong>the</strong>r team’s score. Themoderator will give <strong>the</strong> correct answer and move onto <strong>the</strong> next toss-up question.20. If <strong>the</strong> moderator inadvertently gives an answer toa toss-up question without giving ei<strong>the</strong>r team achance to respond, no points are awarded and <strong>the</strong>moderator goes on to <strong>the</strong> next toss-up question.21. If a toss-up question is interrupted, <strong>the</strong> student isnot recognized and blurts out an answer, <strong>the</strong> resultis a nonanswer. No penalty points are awarded to<strong>the</strong> opposing team. The moderator will not indicatewhe<strong>the</strong>r <strong>the</strong> answer was right or wrong and <strong>the</strong>question is reread in its entirety to <strong>the</strong>opposing team.22. If <strong>the</strong> moderator inadvertently gives <strong>the</strong> answer toa toss-up question be<strong>for</strong>e allowing <strong>the</strong> second teamto respond (after an incorrect answer, or an answergiven without <strong>the</strong> team member having beenrecognized), <strong>the</strong> next toss-up question will be readto <strong>the</strong> second team in place of <strong>the</strong> inadvertentlyanswered question.Summary of Scoring:Type of QuestionToss-upBonusIncorrectly answeredInterrupted toss-upUnrecognized andinterrupted toss-upUnrecognized toss-upChallengesPoints Awarded+4 points, and eligible<strong>for</strong> bonus+10 points+4 points to opposingteam+4 points to opposingteam+0 points+0 points23. Challenges to questions and responses will bepermitted. Team members may also challenge aruling, <strong>the</strong> score, or a protocol issue. A challengecan only be made by a team member who is activelycompeting. A challenge may not be made by <strong>the</strong>coach, alternate, or by anyone else in <strong>the</strong> audience.All challenges must be made be<strong>for</strong>e <strong>the</strong> nextquestion is begun. The scientific judge and <strong>the</strong>moderator may consult during <strong>the</strong> match regardingresponses. All decisions made by <strong>the</strong> judgesare final.24. Should a question arise during a competition, <strong>the</strong>competition and <strong>the</strong> clock will be stopped until <strong>the</strong>question is resolved. Once <strong>the</strong> question has beenresolved, <strong>the</strong> match will continue from that point.Should <strong>the</strong> moderator decide that some time waslost due to <strong>the</strong> interruption, <strong>the</strong> moderator has <strong>the</strong>right to put <strong>the</strong> appropriate amount of time backon <strong>the</strong> clock.When time runs out25. If <strong>the</strong> question has been completely read, butnei<strong>the</strong>r team has buzzed in, <strong>the</strong> game or half is over.26. If <strong>the</strong> question has been completely read, a studenthas buzzed in and is recognized be<strong>for</strong>e answering,and gives a correct answer, <strong>the</strong> team gets to answer<strong>the</strong> bonus question. The half or game is <strong>the</strong>n over.27. If <strong>the</strong> question has been completely read, a studenthas buzzed in and is recognized be<strong>for</strong>e answering,but gives <strong>the</strong> wrong answer or answers be<strong>for</strong>e beingverbally recognized, <strong>the</strong> game or half is over.28. If <strong>the</strong> question has been completely read, a studenthas buzzed in and time is called be<strong>for</strong>e <strong>the</strong> studenthas been recognized, <strong>the</strong> moderator or scientificjudge will verbally recognize <strong>the</strong> student. If <strong>the</strong>student gives a correct answer, <strong>the</strong> team gets toanswer <strong>the</strong> bonus question. If an incorrect answer isgiven or <strong>the</strong> student answers be<strong>for</strong>e being verballyrecognized, <strong>the</strong> game or half is over.If <strong>the</strong> question has NOT been read completelybe<strong>for</strong>e time runs out:29. If <strong>the</strong> question has not been completely read by <strong>the</strong>moderator and nei<strong>the</strong>r team has buzzed in(interrupted), <strong>the</strong> game or half is over.30. If a team member buzzes in be<strong>for</strong>e time is called,interrupting <strong>the</strong> reading of <strong>the</strong> question, is verballyrecognized, and answers <strong>the</strong> question correctly, <strong>the</strong>team gets to answer <strong>the</strong> bonus question. The half orgame is <strong>the</strong>n over.31. If a team member buzzes in be<strong>for</strong>e time is called,interrupting <strong>the</strong> reading of <strong>the</strong> question, and isF u e l C e l l C o m p e t i t i o n s181
F u e l C e l l C o m p e t i t i o n sverbally recognized, but answers <strong>the</strong> questionincorrectly, penalty points are awarded, <strong>the</strong> questionis reread <strong>for</strong> <strong>the</strong> o<strong>the</strong>r team, which is <strong>the</strong>n given <strong>the</strong>chance to answer both <strong>the</strong> toss-up questionand, if correct, <strong>the</strong> bonus question be<strong>for</strong>e <strong>the</strong>contest or half is over.32. If a team member buzzes in be<strong>for</strong>e time is called, isnot verbally recognized, and blurts out <strong>the</strong> answer,<strong>the</strong> answer is not accepted but no penalty points areawarded. The question is read in its entirety <strong>for</strong> <strong>the</strong>o<strong>the</strong>r team which, if it answers correctly, is alsogiven a chance to answer <strong>the</strong> bonus question be<strong>for</strong>e<strong>the</strong> contest or half ends.Rules <strong>for</strong> entering <strong>the</strong> final round33. In <strong>the</strong> event that <strong>the</strong> required number of teamsfrom each division is not clearly identifiable[resolution is necessary only between teams tied <strong>for</strong>last position(s) to advance to <strong>the</strong> single or doubleelimination], a tie-break procedure in <strong>the</strong> followingorder will be used:a) Head to head won/loss recordb) Fewest lossesc) If two teams are still tied, <strong>the</strong>re will be a fivetoss-up question run-off (interrupt penalty ineffect). No bonus questions will be used duringthis segment of <strong>the</strong> competition. If still tied,ano<strong>the</strong>r five toss-up question run-off will beused, etc. until <strong>the</strong> advancing team isdetermined.d) If more than two teams are tied, each team, inseparate rooms, will be given a series of 10toss-up questions (no bonus questions will beused during this segment of <strong>the</strong> competition).The usual 10 seconds will be allowed <strong>for</strong> acompetitor to buzz in after <strong>the</strong> question iscompletely read. There are no interruptpenalties but also no reason to interrupt sinceall 10 questions will be read. Scoring will bebased on <strong>the</strong> number of questions right minus<strong>the</strong> number wrong. If two or more teams arestill tied, procedure (iii) or (iv), as appropriate,will be used until <strong>the</strong> advancing teams aredetermined.[. . .]Rules <strong>for</strong> <strong>the</strong> end of a single or doubleelimination match51. If <strong>the</strong> score is tied in a single or double eliminationmatch at <strong>the</strong> end of <strong>the</strong> regulation time period, aseries of five toss-up questions will be used to break<strong>the</strong> tie. Interrupt penalties are in effect. Round robinmatches may end in a tie, as explained in rule15 above.Miscellaneous science bowl rules52. No one in <strong>the</strong> audience may communicate withparticipants during <strong>the</strong> match; communication willresult in a warning, and if <strong>the</strong> problem persists couldresult in an ejection from <strong>the</strong> competition room.53. If someone in <strong>the</strong> audience shouts out an answer,<strong>the</strong> question will be thrown out (as will <strong>the</strong> person),and <strong>the</strong> moderator will proceed to <strong>the</strong> next question.54. Prior to each match, <strong>the</strong> two team coaches willintroduce <strong>the</strong>mselves to each o<strong>the</strong>r and will sittoge<strong>the</strong>r in <strong>the</strong> back row of <strong>the</strong> competition room.55. No notes may be brought to <strong>the</strong> competition.Nothing may be written be<strong>for</strong>e <strong>the</strong> clock starts.Scratch paper will be provided at <strong>the</strong> beginning ofeach match, and collected at half-time and at <strong>the</strong>conclusion of <strong>the</strong> match.56. Calculators are not permitted.57. Members of <strong>the</strong> audience, including <strong>the</strong> coaches,will not write down <strong>the</strong> questions or answers <strong>the</strong>moderator reads, or use any electronic recording ortransmitting device, including digital camerasduring <strong>the</strong> match. At <strong>the</strong> nationals, coaches will beprovided with a team score sheet to track <strong>the</strong>number of questions answered by each individualstudent on <strong>the</strong>ir team. No one else in <strong>the</strong>competition room is permitted to make notes of anykind during <strong>the</strong> active competition. If this occurs,<strong>the</strong> individual(s) will be asked to leave <strong>the</strong>competition room.Hydrogen student design contestThe hydrogen student design contest is an annualcompetition that takes students with a knowledge182
of fuel cell technology, and gets <strong>the</strong>m to apply thisknowledge to a design problem. The contestfocuses on practical applications utilizinghydrogen and fuel cells.Fur<strong>the</strong>r in<strong>for</strong>mation is available from:www.hydrogencontest.org/The rules vary every year as different challengesare set annually.Department of Energy NationalScience Bowl (United States)The DOE National Science Bowl includes an eventin <strong>the</strong> finals—<strong>the</strong> “Hydrogen <strong>Fuel</strong> <strong>Cell</strong> Model CarChallenge.” For this, apply principles that you havelearned from <strong>the</strong> chapter on hydrogen transport(Chapter 13).More info about <strong>the</strong> DOE Science Bowl can befound at:www.scied.science.doe.gov/nsb/index.html<strong>Fuel</strong> <strong>Cell</strong> Box (Germany)A national competition to raise awareness aboutfuel cell technology among schoolchildren inGermany called “<strong>Fuel</strong> <strong>Cell</strong> Box” may be ofinterest to you. Fur<strong>the</strong>r in<strong>for</strong>mation, in German, isavailable from www.fuelcellbox.de.F u e l C e l l C o m p e t i t i o n s183
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AppendixAEverything You Wanted to KnowAbout Hydrogen ... and Then SomeChemical series NonmetalsGroupPeriod, Block 1, 1, sElectron configuration 1s1Electrons per shell 1AppearanceColorlessGas* (m 3 ) Liquid (liter) Weight (kg)1 1.163 0.08980.856 1 0.070912.126 14.104 1*m 3 at 981 mbar and 15° CDataValueDensity 0.08988 kg/nm 3Upper heating value 12.745 MJ/nm 3Lower heating value 10.783 MJ/nm 3Ignition energy 0.02 MJIgnition temperature 520 CLower ignition level (gas concentration in air)4.1 Vol%Upper ignition level (gas concentration in air)72.5 Vol%Flame rate2.7 m/sMelting point 14.01 K (−259.14 C,− 434.45 F)DataValueBoiling point 20.28 K (−252.87 C,− 423.17 F)Triple point13.8033 K, 7.042 kPaCritical point32.97 K, 1.293 MPaHeat of fusion (H 2) 0.117 kJ·mol −1Heat of vaporization (H 2) 0.904 kJ·mol −1Heat capacity−128.836 J·mol−1·K (25° C) (H 2)Thermal conductivity–1180.5 mW·m−1·K (300 K)Speed of sound (gas, 27 C) 1310 m/sCAS registry number 1333-74-0 (H 2)Crystal structure hexagonalOxidation states 1, −1Electronegativity 2.20 (Pauling scale)Ionization energies 1st: 1312.0 kJ/molAtomic radius 25 pmAtomic radius (calc.) 53 pm (Bohr radius)Covalent radius 37 pmVan der Waals radius 120 pm185Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
Hydrogen density compared to o<strong>the</strong>r fuels:E v e r y t h i n g y o u W a n t e d t o K n o w A b o u t H y d r o g e n . . .Hydrogen Gasoline Diesel Natural gas MethanolDensity (kg/l) 0.0000898 0.702 0.855 0.00071 0.799Density (kg/m 3 ) 0.0898 702 855 0.71 799Energy density (MJ/kg) 120 42.7 41.9 50.4 19.9Energy density (MJ/l) 0.01006 31.2 36.5 0.00361 15.9Energy density (MJ/m 3 ) 10783 31200 36500 36.1 18000Energy density (kWh/kg) 33.3 11.86 11.64 14 5.53Energy density (kWh/m 3 ) 2.79 8666.67 10138.88 10.02 4420All numbers are at lower heating value and at atmospheric pressure and normal temperature.186
Appendix B<strong>Fuel</strong> <strong>Cell</strong> Acronym BusterIn <strong>the</strong> world of fuel cells, <strong>the</strong>y love to abbreviatethings! You will come across some of <strong>the</strong>seacronyms in this book, while o<strong>the</strong>rs you will findare used in conversation and o<strong>the</strong>r books whenlooking at fuel cells and <strong>the</strong>ir applications. Thishandy little guide should help to debunk <strong>the</strong> TLAs(Three Letter Acronyms) into something a littlemore intelligible.AFC alkaline fuel cellAFV alternative fuel vehicleBEV battery electric vehicleCH 3OH methanolCH 3CH 2OH ethanolCHP combined heat and powerCNG compressed natural gasCO carbon monoxideCO 2carbon dioxideDMFC direct methanol fuel cellFC fuel cellFCEV fuel cell electric vehicleGDE gas diffusion electrode (See GDM)GDM gas diffusion media/membrane (See GDE)FC fuel cellFCEV fuel cell electric vehicleGHG greenhouse gasH 2hydrogenHC hydrocarbonsICE internal combustion engineLPG liquefied petroleum gasMCFC molten carbonate fuel cellMEA membrane electrode assemblyMeOH methanolNABH 4sodium borohydride or sodiumtetrahydroborateNO xoxides of nitrogenO 2oxygenPAFC phosphoric acid fuel cellPEFM polymer electrolyte fuel cellPEM proton exchange membrane or polymerelectrolyte membranePEMFC PEM (see above) fuel cellPd palladiumPt platinumSOFC solid oxide fuel cellURFC unitized regenerative fuel cell187Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
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Appendix C<strong>Fuel</strong> <strong>Cell</strong> AssociationsIf you are interested in finding out what schools,colleges, and universities run courses in your area,or if you are interested in work experience andwant to find a suitable company, or if you aresimply interested in what’s happening withhydrogen in your area, contact your local hydrogenassociation, where <strong>the</strong>y will be more than happy togive you in<strong>for</strong>mation to fur<strong>the</strong>r your interest inhydrogen and fuel cells.EuropeEuropean Hydrogen AssociationGulledelle 981200 BruxellesBelgiumTel: 32 2 763 25 61Fax: 32 2 772 50 44E-mail: info@h2euro.orgwww.h2euro.orgFrench Hydrogen AssociationAssociation Française de l’Hydrogène28, rue Saint-Dominique75007 ParisTel: 33 (0)1 53 59 02 11Fax: 33 (0)1 45 55 40 33E-mail: info@afh2.orgwww.afh2.org/<strong>Fuel</strong> <strong>Cell</strong> Europe<strong>Fuel</strong> <strong>Cell</strong> EuropeWorld <strong>Fuel</strong> <strong>Cell</strong> Council e.V.Frankfurter Strasse 10-14,D-65760 EschbornGermanywww.fuelcelleurope.org<strong>Fuel</strong> <strong>Cell</strong>s UKSynnogy Ltd1 Aldwincle RoadThorpe WatervilleNorthants NN14 3EDTel: 44 (0)1832 720007E-mail: info@fuelcellsuk.orgwww.fuelcellsuk.orgGerman <strong>Fuel</strong> <strong>Cell</strong> AssociationUnter den Eichen 8712205 BerlinGermanyTel: (49-700) 49376 835 (hydrotel)Fax: (49-700) 49376 329 (hydrofax)E-mail: h2@dwv-info.deNorwegian Hydrogen Forumradix.ife.no/nhf/Polish Hydrogen and <strong>Fuel</strong> <strong>Cell</strong> AssociationPolskie Stowarzyszenie Wodoru i OgniwPaliwowychmolenda@uci.agh.edu.pl orhydrogen@agh.edu.plE-mail: www.hydrogen.edu.pl189Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
<strong>Fuel</strong> <strong>Cell</strong> AssociationsScottish Hydrogen and <strong>Fuel</strong> <strong>Cell</strong> AssociationBrunel BuildingJames Watt AvenueScottish Enterprise Technology ParkEast KilbrideG75 0QDScotlandTel: 44 7949 965 908www.shfca.org.ukSpanish Hydrogen AssociationAsociación Española del HidrógenoHead Office:c/o Isaac Newton, 1PTM. Tres Cantos28760 MadridSpainCIF: G-83319731Tel: 34.654.80.20.50Fax 34.91.771.0854E-mail: info@aeh2.org (about AeH2)E-mail: aeh.web@ariema.com (about this website)aeh2.org/en/index.htmAmericaAmerican Hydrogen Association2350 W. Shangri LaPhoenix, AZ 85028Tel: (602) 328-4238<strong>Fuel</strong> <strong>Cell</strong>s Texasc/o Good Company Associates Inc.816 Congress Avenue, Ste. 1400Austin, TX 78701Tel: (512) 279-0750Fax: (512) 279-0760www.fuelcellstexas.org/Hydrogen and <strong>Fuel</strong> <strong>Cell</strong>s Canada4250 Wesbrook MallVancouver, B.C. V6T 1W5Tel: 604-822-9178Fax: 604-822-8106E-mail: admin@h2fcc.caNational Hydrogen AssociationMain Office:1800 M St NW, Suite 300 NorthWashington, DC 20036-5802U.S.A.Tel: 202-223-5547Fax: 202-223-5537Western U.S. Office35 Seacape DriveSausalito, CA 94965Tel: 415-381-7225Fax: 415-381-7234E-mail:infoWestUS@ttcorp.comwww.hydrogenassociation.org/North Carolina Sustainable Energy AssociationNCSEAPO Box 6465Raleigh, NC 27628-6465Tel: 919-832-7601E-mail: ncsea@mindspring.comwww.ncsustainableenergy.org/190
AsiaChina Association <strong>for</strong>Hydrogen Energy (CAHE)Room 710No. 86 Xueyuan NanluBeijing100081ChinaTel: (86-10) 62180145Fax: (86-10) 62180142OceaniaNational Hydrogen Association of Australia13 Mount Huon CCTGlen AlpineCampbelltownNew South Wales 2560AustraliaTel: 61 2 9603 7967Fax: 61 2 9603 8861www.hydrogen.org.au/nhaa/<strong>Fuel</strong> <strong>Cell</strong> Associations191
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EpilogueWhat does <strong>the</strong> future hold <strong>for</strong> fuel cells? Whydon’t I ask you <strong>the</strong> same question? You’re <strong>the</strong> onewith this book in your hand, a head full of greatideas, and a desk full of fuel cell equipment—goand create <strong>the</strong> next generation of sustainablypowered inventions, gadgets, and gizmos.<strong>Fuel</strong> cells have already undeniably helped toshape <strong>the</strong> world—<strong>the</strong>y’ve helped us in our questto conquer <strong>the</strong> mysteries of space, by producingelectricity to power space capsules, while providingwater <strong>for</strong> astronauts to drink. They’ve also helped ussubjugate <strong>the</strong> oceans, allowing submarines to stayunderwater <strong>for</strong> weeks on end.The challenge now, as <strong>the</strong> technology findsmore applications, is to vanquish our addiction tocarbon-based fuels. It’s a bad habit which we’veacquired over <strong>the</strong> past couple of centuries, but onethat we need to kick quickly, as we have limitedresources, and are faced by <strong>the</strong> problems ofenvironmental degradation, photochemical smog,and <strong>the</strong> threat of climate change—all nasty side-effectsof an infatuation with coal and oil.The fuel cell will enable a cleaner economy—based on hydrogen, not carbon—facilitating atransition to greener technologies and new models<strong>for</strong> providing power and energy services. <strong>Fuel</strong> celltechnology is going to release consumers of powerfrom <strong>the</strong> shackles, and inefficiency of centralized<strong>the</strong>rmal generation (where <strong>the</strong> bulk of <strong>the</strong> inputenergy is wasted as heat) to new modes ofdecentralized generation, where <strong>the</strong> heat producedfrom an energy conversion process is used togood effect—to heat your home or to warm yourcommunity’s swimming pool, ra<strong>the</strong>r than beingwasted into <strong>the</strong> atmosphere in plumes ofsmoke.It’s also going to enable us to use increasedamounts of renewable energy as part of our energygeneration portfolio—we can only produce solarpower when <strong>the</strong> sun shines, and wind power when<strong>the</strong> wind blows, but we need mechanisms to storeit when it’s being produced but not used. Again,fuel cells are very helpful here as <strong>the</strong>y enable us to“mop up” spare energy when a surplus is beingproduced, and store it as hydrogen later tobe used as a transport fuel, or converted intoelectricity.At <strong>the</strong> PURE Energy Centre, Shetland, UK and<strong>the</strong> HARI project, West Beacon Farm, UK, <strong>the</strong>yare doing just that—learning by experiment, justas you’re doing with this book, how to usehydrogen produced from renewables to meet<strong>the</strong>ir energy needs.The technology is developing every day,and every person that joins <strong>the</strong> army ofscientists, engineers, technologists, andproduct designers working to bring fuel cellsonto <strong>the</strong> market and into <strong>the</strong> mainstream,helps <strong>the</strong> movement gain a little bit ofmomentum.The future is bright <strong>for</strong> hydrogen—HjaltlandHousing Association, along with <strong>the</strong> PURE EnergyCentre and <strong>Fuel</strong> <strong>Cell</strong>s Scotland, have releasedplans <strong>for</strong> <strong>the</strong> world’s first off-grid fuel cell houses.The houses will have wind turbines in <strong>the</strong>ir yard toproduce power, and will turn this power intohydrogen which can be used to meet <strong>the</strong> homes’energy needs.This sort of development provides a blueprint<strong>for</strong> clean homes around <strong>the</strong> world, and could becoming to a block near you.193Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
Architects drawing <strong>for</strong> Hjaltland Housing Associationfuel cell homes. Image courtesy PURE Energy CentreDon’t let people put you off fuel cells by sayingthat <strong>the</strong>y are expensive and will never be af<strong>for</strong>dable—remember that big TV your Pa wanted a few yearsago, but was a touch on <strong>the</strong> pricey side . . . that hebought last week because it was a third of <strong>the</strong>price, or that games console that a couple ofChristmases ago was at a premium price, but nowhas dropped in price and is a bit more af<strong>for</strong>dable?It’s all proof that <strong>the</strong>re is a relentless drive toengineer <strong>the</strong> cost out of technology to make itaccessible to a wider marketplace. Fifty years ago,it would have been inconceivable <strong>for</strong> every one of<strong>the</strong> world’s large corporations to have a computer.Today, <strong>the</strong>y are on <strong>the</strong> desk of every employee,and fur<strong>the</strong>rmore—with initiatives like “One LaptopPer Child”—<strong>the</strong> technology is even accessible to<strong>the</strong> developing world. The same will happen withfuel cells. Problems are surmounted, cheaper waysto make better products are found, and <strong>the</strong>products become ubiquitous.So watch out . . . fuel cells may be coming to ahome near you. In fact . . . <strong>the</strong>y already have!Epilogue194
IndexPage numbers <strong>for</strong> figures and tables are given in boldAalkaline fuel cell, 6, 7, 7, 74alkaline solutions <strong>for</strong>, 67chemistry of, 57, 57, 58, 59hydrogen carriers <strong>for</strong>, 68IV measurement of, 63–64, 64, 65making electricity with, 59–63oxygen and, 71–74, 73poisoning, 70, 70power curve of, 66, 67temperature and, 68–69BBacon, Francis, 6, 6, 57Bacon <strong>Cell</strong>. See alkaline fuel cellbiomass, 14–15, 23Boyle, Robert, 1, 2Boyle’s Law, 38, 39Ccarbon dioxide, 15–16, 15, 16, 17–19, 18, 19carbon emissions, 23–24. See also carbon dioxidecarbon nanotube, 40–41, 42carbon sequestration, 15–16, 23catalyst, 28–29, 54–55, 78, 80, 80, 88, 129Cavendish, Henry, 1–2, 2Charles, Jacques, 2, 2Charles’ Law, 2–3, 39–40chemical hydride, 42, 43, 44, 44coal, 24complex hydride, 43, 44cryogenic storage, 39–40, 40DDalton, John, 3, 3direct methanol fuel cell, 106activating, 98, 98advantages of, 95Band-Aid ® , 100–105, 104, 105chemistry of, 96, 96, 97decommissioning, 99recommissioning, 99DMFC. See direct methanol fuel cellEelectrolysis, 10, 11, 17, 23using baking soda, 31–32, 32using a Hoffman apparatus, 33, 33using platinum, 53–55, 53, 54using renewable resources, 33–34, 35, 36energy production, 20–21, 20equations, balanced, 25Fflow fields, 82–81, 83, 123–125, 123, 124, 125fossil fuels, 15–16, 23, 24fuel cellalkaline (see alkaline fuel cell)applications, practical, 6–8, 6, 7, 107, 142–144, 144,163–164, 169–172, 170, 174–175, 174, 175, 193associations, 189–191classification, 115competitions, 177–183disassembly, 84–85, 85, 86, 87efficiency, 20–21, 20high temperature, 115–119, 116, 117, 118history of, 1, 5–8, 6membrane (see direct methanol fuel cell; PEM fuel cell)methanol (see direct methanol fuel cell)microbial (see microbial fuel cell)miniature, 90–91, 91, 92, 93, 93molten carbonate, 117–118, 117PEM (see PEM fuel cell)phosphoric acid, 116–117, 117platinum, 51–56, 53, 54, 55scratch-built (see scratch-built fuel cell)solid oxide, 118–119, 118fuel cell vehiclehydrides powered, 156, 156intelligent, 152–153, 154, 155radio-controlled, 157–162, 160, 161, 162simple, 145–147, 146, 147, 148, 149, 149, 150, 151, 152, 152technology, 21, 142–144, 143vs. internal combustion engine, 141–142, 141, 142Ggas diffusion layer, 80–81, 80, 126making your own, 129–131GDL. See gas diffusion layergeo<strong>the</strong>rmal power, 14, 14Grove, Sir William Robert, 5, 5, 6, 51, 55, 56HHARI (Hydrogen and Renewables Integration Project), 34, 35,36, 48H-Gen, 46–48high temperature fuel cell, 115–119, 116, 117, 118Hoffman apparatus, 33, 33hydrides, 41–45, 42, 43, 44hydrogen, 9–11, 9, 10density, 186economy, 21–22, 22195Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here <strong>for</strong> terms of use.
hydrogen (cont.)history of, 1–5production of (see hydrogen production)safety, 135–139storage of, 10, 37, 39–41, 40, 42, 44, 137testing <strong>for</strong>, 24transport (see fuel cell vehicle; hydrogen air travel; hydrogenspace travel)See also fuel cellhydrogen air travelairship, 166–168, 167planes, 163, 163hydrogen productionby acid-metal reactions, 27–30, 27“dirty”, 15, 15–17, 16, 17, 23–24“green”, 10–15, 23, 24, 33–34, 35, 36, 45–46using platinum, 51–55, 53, 54hydrogen space travel, 164–165, 165, 166hydro power, 13Ihrig, Harry, 6, 6IOoxidation, 27–28, 28, 57, 58, 59, 111–112, 111, 112oxygenand fuel cells, 71–74, 73, 89pure, 26, 71–72, 89testing <strong>for</strong>, 26, 26Paracelsus, 1, 1Peak oil, 19, 20PEM fuel cell, 6–7, 7, 77disassembly, 84–85, 85, 86, 87mechanism of action, 77–81, 77, 78, 79, 80miniature, 90–91, 91, 92, 93, 93platinum catalyst effect on, 88, 88phosphoric acid fuel cell, 116–117, 117photoelectrolysis, 24plastic electrolyte membrane fuel cell. See PEMfuel cellproton exchange membrane fuel cell. See PEM fuel cellPURE Energy Centre, 33–34, 48–49PLavoisier, Antoine, 3, 3LRreduction, 27–28, 28, 57, 58, 59, 111–112, 111, 112MMEA. See membrane electrode assemblymembrane electrode assembly (MEA), 87, 125–126making a, 126–128platinum loading and, 88, 88Mendeleev, Dmitri, 3, 5, 5metal hydride, 37, 41, 43, 44, 45metals, activity series of, 31microbial fuel cell, 107future of, 107–108history of, 107with mediator, 112–113, 113without mediator, 108–112, 111, 112molten carbonate fuel cell, 117–118, 117NNafion TM , 80, 80–82, 82, 101, 126–127, 127nuclear power, 16Schönbein, Christian, 5–6, 6scratch-built fuel cellend plates <strong>for</strong>, 121–123flow fields <strong>for</strong>, 123–125gas diffusion layer <strong>for</strong>, 129–131membrane electrode assemblies <strong>for</strong>, 125–128, 131–133solar power, 11–12, 23, 35solid oxide fuel cell, 118–119, 118steam re<strong>for</strong>mation, 15, 23–24tidal power, 13–14wave power, 13–14, 14wind power, 12–13, 34, 34, 35STWI n d e x196