PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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Figure 8.7: Hydrogen Storage Requirement Profile 8.3.3 Biogas Production and Use The amount of biogas available would not be enough to run all of the vehicles on the island. If the available biogas is, instead, used for combined heat and power generation in a suitable Stirling engine, a constant supply of around 7kWe and 21kWth would be available during the winter, and around 4kWe and 12kWth would be available during the summer. This amount on its own may not be enough to merit the use of a district-heating scheme, but would be a useful addition to other fuelled CHP production plant, where it would also not be critical if the demand were to increase unexpectedly. This would, for example, reduce the required wind turbine installed capacity in the previous example by 20 kW. 8.3.4 Biodiesel Production and Use Biodiesel can be used to fuel both vehicles and diesel engines for CHP production. The diesel engines can be used to follow the electricity demand, 260
heat demand or both, or run at constant percentage loadings at different times of the day and year. The engines can be used on there own, or supplemented with hot water storage using excess electricity and heat, and intermittent electricity production from wind turbines, in order to meet the required electricity and heat demands. Various different scenarios were simulated, and a range of results, allowing all demands to be met, are discussed below and summarised in Table 8.2. Biodiesel Electricity Production + Vehicles Biodiesel CHP + Vehicles Biodiesel CHP + Vehicles + Biogas CHP Biodiesel CHP + Electric Vehicles Diesel Wind Water Hot Water Land Farm Land Engines Turbines Heater Storage Used Used kW kW kW litres ha % 50 + 50 261 180 45 50 + 50 100 140 35 50 + 50 200 125 31 30 + 30 140 35 25 + 25 30 2000 120 30 25 + 25 50 50 2500 105 26 20 + 20 Table 8.2: Supply Options for Biodiesel Use 100 50 2500 100 25 30 2000 110 27.5 20 + 20 50 50 2500 95 24 20 + 20 180 50 2000 70 17.5 From the results summarised above, it can be seen that, where biodiesel is used in engines to produce electricity alone, that this is an inefficient use of the fuel supply. The use of the fuel for CHP generation instantly reduces the required plant size and the amount of fuel necessary. When considering the use of CHP it is important to get the balance between the electricity and heat demand as
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Decision Support for New and Renewa
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Abstract The global requirement for
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CONTENTS 1 ENERGY SYSTEMS FOR SUSTA
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5.5 Steam Turbine Model 149 5.6 Fue
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FIGURES Figure 1.1 Final Energy Con
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Figure 7.30 Following Electricity a
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on the use of fossil fuels, energy
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The general increase in energy cons
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supply is reduced or eliminated, lo
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Figure 1.3 The Electricity Supply G
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on different generation mixes depen
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Various studies have been carried o
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provision for smaller areas, and he
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1.7 References [1] The Internationa
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2 Options for New and Renewable Ene
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the amount of usable heat that is g
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the conversion of petrol cars; howe
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set times, producing a constant ele
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partial load. Fast response and sta
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2.3 The Production and Storage of H
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dedicated boiler, which runs contin
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Figure 2.3 A Typical Hydrogen Filli
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part of the natural carbon cycle (a
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Figure 2.4 Layout of a Gasification
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met by process integration and the
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Figure 2.5 The Inputs and Outputs o
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1. Scale for measuring out lye and
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feedstock being used. Sugary feedst
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carbon dioxide via steam reforming.
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• Where CHP is used, the balance
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[22] Vehicle Certification Agency (
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[55] M. A. Paisley, J. M. Irving, R
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3 Approaches to Renewable Energy Sy
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Because of the intermittent nature
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A renewable energy supply evaluatio
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the system are kept. The output of
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There are various models available
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When the use of climate dependant i
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3.5 References [1] M. Muselli, G. N
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4 A Procedure for Demand and Supply
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pumped storage and flywheels), a ba
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for the agricultural vehicle use re
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Figure 4.4 Combining Demands to Tak
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ates for vehicles, engines and othe
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Figure 4.5 Derived Fuel Production
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together if desired, and taken forw
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profiles are output from this part
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dividing the production rate at eac
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As it would be too confusing to sho
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Figure 4.12 Output of the Matching
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However, when more than one transpo
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considered, this amount is added to
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users are alerted if there is not e
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at the matching stage, along with t
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vehicles if they are increased by 1
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If biogas is being considered, the
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The number of timesteps per hour wi
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After the algorithm has been follow
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• Float Charge - once the battery
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Discharge No tank = tank fuel used
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equired (kW) = maxkWh x bulk% (5.16
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An example of the output graph prod
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5.2.1 Required Power Specifically d
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5.2.3 Engine Performance in the Con
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used for gas powered ICEs, but the
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and five times, depending on the nu
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Is PL < Min ? No Is PL = 0 ? No Is
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where Max = maximum energy availabl
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where Ratiopart = heat to electrici
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(including following heat demand wh
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where SFC = specific fuel consumpti
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engines running respectively). If t
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(continued) Is Fuel Available > (4
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of the definition window for a Stir
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and continuous operation. Again, mu
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The performance of a fuel cell is n
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percentage loading, rather than usi
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Is Min = 0 ? No Is Min = PC1 ? No I
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5.6.4 If Fuel Availability is Less
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5.7 Electrolyser Model An electroly
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original calculation of the amount
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5.8 Regenerative Fuel Cell Model A
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following the heat demand. To follo
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C:\ My Documents\ Nic\ Thesis\ Old\
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As 1 kWh = 3610.3 kJ, and using lit
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Add Heat to Water Storage Tank Usin
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Use Stored Hot Water to Supply Heat
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information is given about the over
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[23] K. Foger, B. Godfrey, “Syste
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the gasification and pyrolysis defi
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eing used each day for a continuous
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Where Biogas = Biogas production ra
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6.1.3 Use of Biogas Various options
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The amount of hydrogen that can be
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direct proportion, and the weight o
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produce in total (Nm 3 per tonne fe
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Electricity (kW) = Elec x Feed (6.1
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3. Make hydrogen via steam reformin
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Where Methane = Methane Production
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(continued) Keep as medium heating
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Yes Feed1 = Yield1 x Land1 / No. of
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production and energy use profiles
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If it is the last timestep of the p
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For each process, the process chara
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Page 215 and 216: 6.5 Electrolysis As it is sometimes
Page 217 and 218: 6.7 Landfill Gas Processing As the
Page 219 and 220: Demand Profile Design & Profile Dat
Page 221 and 222: Figure 7.2 Degree-Days Versus Month
Page 223 and 224: Stage 1 - Sustainable Fuel Supply S
Page 225 and 226: The different profile of use graphs
Page 227 and 228: Figure 7.3 Fermentation System Inpu
Page 229 and 230: Figure 7.7 Fermentation System Info
Page 231 and 232: Figure 7.10 Fermentation System Out
Page 233 and 234: The output obtained when a second h
Page 235 and 236: Figure 7.16 Anaerobic Digestion Par
Page 237 and 238: Figure 7.19 Fermentation System Inp
Page 239 and 240: clarity. A constant supply rate of
Page 241 and 242: Figure 7.25 Heat Demand Profile Fig
Page 243 and 244: Figure 7.28 Effect of Minimum Load
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Page 247 and 248: Figure 7.35 Second Engine: Followin
Page 249 and 250: This chapter described how the over
Page 251 and 252: heat and electricity during the tou
Page 253 and 254: Figure 8.2: Overall Yearly Heat Dem
Page 255 and 256: to allow for efficient operation du
Page 257 and 258: would be incurred, and the scale of
Page 259: Figure 8.5: Electricity Supply and
Page 263 and 264: ut with 30% less land being require
Page 265 and 266: 9 Conclusions and Recommendations T
Page 267 and 268: through these, technically viable p
Page 269 and 270: considered. The introduction of coo
Page 271 and 272: When considering larger geographica
Page 273 and 274: Appendix 1: Program Windows Figure
Page 275 and 276: Figure A1.5 CreateClimate.exe Figur
Page 277 and 278: Figure A1.9: Demand Profile Designe
Page 279 and 280: Figure A1.13: Derived Fuel Supply W
Page 281 and 282: Figure A1.17: Fermentation System D
Page 283 and 284: Figure A1.21: PV Electrolysis Syste
Page 285 and 286: Figure A1.25: Fuel Supply Profile D
Page 287 and 288: Figure A1.29: Auxilliary Supply Def
Page 289 and 290: Figure A1.33: Stirling Engine Syste
Page 291 and 292: Figure A1.37: Fuel Cell System Defi
Page 293 and 294: Figure A1.41: Electric Vehicle Syst
Page 295 and 296: Figure A1.45: Vehicle Conversion Fa
Page 297 and 298: Figure A1.49: Heating System Defini
Page 299 and 300: Figure A1.53: Pumped Hydro System D
Page 301: Figure A1.57: Auto Search Evaluatio
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PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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