Environmental Problems, Their Causes, and Sustainability 1

ABCombustion engine:Small, efficient internalcombustion enginepowers vehicle withlow emissions.Fuel tank:Liquid fuel such asgasoline, diesel, orethanol runssmall combustionengine.BDEFuelElectricityCCDEElectric motor:Traction drive providesadditional power,recovers braking energyto recharge battery.Battery bank:High-density batteriespower electric motorfor increased power.Regulator:Controls flow ofpower between electricmotor and battery bank.FFATransmission:Efficient 5-speedautomatictransmission.Figure 18-9 Solutions: general features of a car powered by a hybridgas–electric engine. A small internal combustion engine recharges thebatteries, thus reducing the need for heavy banks of batteries and solvingthe problem of the limited range of conventional electric cars. The bodiesof future models will probably be made of lightweight composite plasticsthat offer more protection in crashes, do not need to be painted, do notrust, can be recycled, and have fewer parts than conventional car bodies.(Concept information from DaimlerChrysler, Ford, Honda, and Toyota)Another type of superefficient car is an electric vehiclethat uses a fuel cell—a device that combineshydrogen gas (H 2 ) and oxygen gas (O 2 ) fuel to produceelectricity and water vapor (2 H 2 O 2 2H 2 O)(Figure 18-10).Fuel cells are at least twice as efficient as internalcombustion engines, have no moving parts, require littlemaintenance, and produce little or no pollution dependingon how their hydrogen fuel is produced.Most major automobile companies have developedprototype fuel-cell cars. They hope to have a variety ofaffordable fuel-cell vehicles on the market by 2020(with a few models available by 2010) and greatly increasetheir use by 2050. Until then hybrids will probablyhave an advantage because they are available nowand get their fuel from regular filling stations insteadof having to depend on building a new network of hydrogenfilling stations.In 2001, Bill Ford, grandson of Henry Ford andchairman of the Ford Motor Company, said, “I believeAnode (-)CatalystCathode (+)1 Cell splits H 2 into protonsand electrons. Protons flowacross catalyst membrane.2 React with oxygen (O 2 ).3 Produce electricalenergy (flow ofelectrons) topower car.4 Emits water(H 2 O) vapor.4Anode (-)21H 2CatalystHydrogen gasCathode (+)3O 2ABFuel cell stack:Hydrogen and oxygencombine chemically toproduce electricity.Fuel tank:Hydrogen gas or liquidor solid metal hydridestored on board or madefrom gasoline or methanol.CDETurbo compressor:Sends pressurized airto fuel cell.Traction inverter:Module converts DCelectricity from fuel cell toAC for use in electric motor.Electric motor / transaxle:Converts electrical energyto mechanical energy toturn wheels.H 2 OBDCFigure 18-10 Solutions: general features of an electric carpowered by a fuel cell running on hydrogen gas. The hydrogencan be produced from natural gas, gasified coal, or methanol,or by using renewable energy sources such as wind turbines orsolar cells to produce electricity needed to decompose waterinto hydrogen and oxygen gas. Prototype models are on theroad now and manufacturers hope to have some models ofsuch cars on the market within a decade. (Concept informationfrom DaimlerChrysler, Ford, Ballard, Toyota, and Honda)FuelElectricityAEhttp://biology.brookscole.com/miller14385