汽车新能源与排放控制（双语教学版）Chapter 6

Chapter6:

ElectricVehiclesFig6.1.GeneralMotorsEV1electriccar(1996-1998),storytoldinmovie“WhoKilledtheElectricCar?”6.1Background6.1.1DefinitionMankindisbecomingincreasinglyconcernedaboutthedamageitiscausingtotheenvironment,andelectricvehiclesareperceivedtoplayapartinredressingthebalance.Itisthereforeimportantthattheenvironmentalimpactofelectricvehiclesisthoroughlyunderstood.6.1Background6.1.2VehiclePollutionFig6.2IndicativeenergyuseforICengineandbatterypoweredcars.Obviouslytheprecisefiguresvaryverygreatlywithsizeanddesignofvehicle.Thesefiguresarenotthewholewell-to-wheelenergyfigures,butjustthetank-to-wheelorbattery-to-wheelfigures6.2ElectricVehicletypes6.2.1BatteryElectricVehiclesFig6.3：BatteryElectricVehicles6.2ElectricVehicletypesFig6.4NissanLeafFig6.5BatteryelectricbusbyBYDintheNetherlandsFig6.6TheTeslaModelSistheworld'ssecondbestsellingall-electriccar,withglobalsalesofabout100,000unitsbyearlyDecember2015.6.2ElectricVehicletypesFig6.7:75watt-hour/kilogramlithiumionpolymerbatteryprototypes.NewerLi-polycellsprovideupto130Wh/kgandlastthroughthousandsofchargingcycles.6.2ElectricVehicletypes6.2.2Plug‐inHybridElectricVehiclesFig.6.8:plug-inelectricvehicle6.2ElectricVehicletypesFig6.9TheChevroletVolt/OpelAmperafamilyistheworld'stopsellingplug-inhybrid.Globalsalespassedthe100,000unitmilestoneinOctober2015.6.2ElectricVehicletypes6.2.3HydrogenFuelCellVehiclesFig6.10:Hybridelectricvehicle6.2ElectricVehicletypes6.2ElectricVehicletypes6.2.4Hybridelectricvehicle(a)Shape(b)StructureFig6.13ToyotaPrius6.3PropertiesofEVs6.3.1EnergysourcesAlthoughEVshavefewdirectemissions,allrelyonenergycreatedthroughelectricitygeneration,andwillusuallyemitpollutionandgeneratewaste,unlessitisgeneratedbyrenewablesourcepowerplants.SinceEVsusewhateverelectricityisdeliveredbytheirelectricalutility/gridoperator,EVscanbemademoreorlessefficient,pollutingandexpensivetorun,bymodifyingtheelectricalgeneratingstations.Thiswouldbedonebyanelectricalutilityunderagovernmentenergypolicy,inatimescalenegotiatedbetweenutilitiesandgovernment.6.3PropertiesofEVs6.3.2Charging

(1)Gridcapacity(2)Chargingstations(3)Batteryswapping(4)ChargingtimeFig6.14Chargingstationsforelectricvehicles6.3PropertiesofEVsFig6.15U.S.(left)andEuropean(right)trafficsignusedforEVchargingstation6.3PropertiesofEVs6.3.3Otherin‐developmenttechnologiesConventionalelectricdouble-layercapacitorsarebeingworkedtoachievetheenergydensityoflithiumionbatteries,offeringalmostunlimitedlifespansandnoenvironmentalissues.Electricdouble-layercapacitorscouldimprovelithiumionenergydensityseveraltimesoveriftheycanbeproduced.Lithium-sulphurbatteriesoffer250Wh/kg.Sodium-ionbatteriespromise400Wh/kgwithonlyminimalexpansion/contractionduringcharge/dischargeandaveryhighsurfacearea.

ThereisagrowingconcernaboutthesafetyofEVs,giventhedemonstratedtendencyoftheLithium-ionbattery,mostpromisingforEVusebecauseofitshighenergydensity,tooverheat,possiblyleadingtofireorexplosion,especiallywhendamagedinacrash.6.4AdvantagesanddisadvantagesofEVs6.4.1EnvironmentalEVsreleasenotailpipeairpollutantsattheplacewheretheyareoperated.Theyalsotypicallygeneratelessnoisepollutionthananinternalcombustionenginevehicle,whetheratrestorinmotion.Theenergythatelectricandhybridcarsconsumeisusuallygeneratedbymeansthathaveenvironmentalimpacts.Nevertheless,adaptionofEVswouldhaveasignificantnetenvironmentalbenefit,exceptinafewcountriesthatcontinuetorelyonoldercoalfiredpowerplantsforthebulkoftheirelectricitygenerationthroughoutthelifeofthecar.6.4AdvantagesanddisadvantagesofEVs6.4.2MechanicalFig6.16TeslaModelSchassiswithdrivemotor6.4AdvantagesanddisadvantagesofEVs6.4.3EnergyefficiencyEV“tank-to-wheels”efficiencyisaboutafactorof3higherthaninternalcombustionenginevehicles.Energyisnotconsumedwhilethevehicleisstationary,unlikeinternalcombustionengineswhichconsumefuelwhileidling.However,lookingatthewell-to-wheelefficiencyofEVs,theirtotalemissions,whilestilllower,areclosertoanefficientgasolineordieselinmostcountrieswhereelectricitygenerationreliesonfossilfuels.6.4.4CostofrechargeTherealityisthatthecostofoperatinganEVvarieswildlydependingonthepartoftheworldinwhichtheownerlives.InsomelocationsanEVcostslesstodrivethanacomparablegas-poweredvehicle,aslongasthehigherinitialpurchase-priceisnotfactoredin(i.e.apurecomparisonofgasolinecosttoelectricitycost).6.4AdvantagesanddisadvantagesofEVs

6.4.5StabilizationofthegridSinceEVscanbepluggedintotheelectricgridwhennotinuse,thereisapotentialforbatterypoweredvehiclestoevencutthedemandforelectricitybyfeedingelectricityintothegridfromtheirbatteriesduringpeakuseperiods(suchasmidafternoonairconditioninguse)whiledoingmostoftheirchargingatnight,whenthereisunusedgeneratingcapacity.Thisvehicle-to-grid(V2G)connectionhasthepotentialtoreducetheneedfornewpowerplants,aslongasvehicleownersdonotmindreducingthelifeoftheirbatteries,bybeingdrainedbythepowercompanyduringpeakdemand.

6.4.6HeatingofEVsIncoldclimates,considerableenergyisneededtoheattheinteriorofavehicleandtodefrostthewindows.Withinternalcombustionengines,thisheatalreadyexistsaswastecombustionheatdivertedfromtheenginecoolingcircuit.Thisprocessoffsetsthegreenhousegases'externalcosts.6.5HydrogenFuelCellVehicles6.5.1Thebenefitsofhydrogen‐poweredvehiclesHydrogenFCVsareconsideredoneofseveralpossiblelong-termpathwaysforlow-carbonpassengertransportation(otheroptionsincludevehiclespoweredbyelectricityand/orbiofuels).Thebenefitsofhydrogen-poweredvehiclesincludethefollowing:Highenergyefficiencyoffuelcelldrivetrains,whichuse40to60percentoftheenergyavailablefromhydrogen,comparedtointernalcombustionengines,whichcurrentlyuseonlyabout20percentoftheenergyfromgasoline;Diversemethodsbywhichhydrogencanbeproduced;Unlikeall-electricvehicles(EVs),comparablevehiclerangeandrefuelingtimetogasolinevehicles;SimilartoEVs,quickstartsduetohightorquefromtheelectricmotorandlowoperatingnoise;andLackofanygreenhousegas(GHG)emissionsandfewotherairpollutantsduringvehicleoperationandthepotentialforverylowornoupstreamGHGemissionsassociatedwithhydrogenfuelproduction.6.5HydrogenFuelCellVehicles6.5.2MajorcomponentsFig6.17:Majorcomponents6.5HydrogenFuelCellVehicles(1)Fuelcellstack:Fig6.17:PEMfuelcell6.5HydrogenFuelCellVehicles(2)HydrogenstoragetankFig6.19:FCVchassis6.5HydrogenFuelCellVehicles(3)ElectricmotorandpowercontrolunitThepowercontrolunitgovernsflowofelectricityinthevehicle.Bydrawingpowerfromeitherthebatteryorthefuelcellstack,itdeliverselectricpowertothemotor,whichthenusestheelectricitytopropelthevehicle.(4)BatteryLikeHEVs,FCVsalsohaveabatterythatstoreselectricitygeneratedfromregenerativebraking,increasingtheoverallefficiencyofthevehicle.Thesize