Page - 6 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2017,10, 1217 Figure5.ExampleofenergymanagementstrategyusedinHEV.Thecontroller splitspowerbetween the ICEandthemotorbyconsideringdifferent inputparameters.Adaptedfrom[8]. 2.3. Plug-InHybridElectricVehicle (PHEV) ThePHEVconceptarose toextendtheall-electric rangeofHEVs[9–14]. ItusesbothanICEand anelectricalpower train, likeaHEV,but thedifferencebetweenthemis that thePHEVuseselectric propulsionas themaindrivingforce, so thesevehiclesrequireabiggerbatterycapacity thanHEVs. PHEVsstart in ‘all electric’mode, runsonelectricityandwhenthebatteriesare lowincharge, it calls on the ICE toprovideaboostor to chargeup thebatterypack. The ICE isusedhere toextend the range. PHEVscanchargetheirbatteriesdirectly fromthegrid(whichHEVscannot); theyalsohavethe facility toutilizeregenerativebraking. PHEVs’ability torunsolelyonelectricity formostof the time makes its carbonfootprint smaller than theHEVs. Theyconsumeless fuelaswell andthusreduce theassociatedcost. Thevehiclemarket isnowquitepopulatedwith these,ChevroletVoltandToyota Priussalesshowtheirpopularityaswell. 2.4. FuelCellElectricVehicle (FCEV) FCEVsalsogobythenameFuelCellVehicle (FCV).Theygot thenamebecause theheartof such vehicles is fuel cells thatuse chemical reactions toproduceelectricity [15]. Hydrogen is the fuelof choice forFCVstocarryout this reaction, so theyareoftencalled ‘hydrogenfuelcellvehicles’. FCVs carry thehydrogeninspecialhighpressure tanks,another ingredient for thepowergeneratingprocess isoxygen,which itacquires fromtheair suckedinfromtheenvironment. Electricitygeneratedfrom the fuel cells goes toanelectricmotorwhichdrives thewheels. Excess energy is stored in storage systems likebatteriesor supercapacitors [2,3,16–18]. CommerciallyavailableFCVs like theToyota MiraiorHondaClarityusebatteries for thispurpose. FCVsonlyproducewaterasabyproductof its powergeneratingprocesswhich isejectedoutof thecar throughthetailpipes. Theconfigurationof anFCVisshowninFigure6.Anadvantageofsuchvehicles is theycanproduce theirownelectricity whichemitsnocarbon,enabling it toreduce itscarbonfootprint further thananyotherEV.Another majoradvantageof theseare,andmaybethemost importantonerightnow,refillingthesevehicles takes the sameamount of time required tofill a conventional vehicle at a gaspump. Thismakes adoptionof thesevehiclesmore likely in thenear future [2–4,19].Amajorcurrentobstacle inadopting this technologyis thescarcityofhydrogenfuelstations,but thenagain,BEVorPHEVchargingstations werenotacommonscenarioevenafewyearsback.Areport to theU.S.DepartmentofEnergy(DOE) pointedtoanotherdisadvantagewhich is thehighcostof fuel cells, thatcostmore than$200perkW, which is fargreater thanICE(less than$50perkW)[20,21]. Therearealsoconcernsregardingsafety in case offlammablehydrogen leakingout of the tanks. If these obstacleswere eliminated, FCVs could really represent the future of cars. Thepossibilities of using this technology in supercars is shownbyPininfarina’sH2Speed(Figure7). Reference [22]comparedBEVsandFCEVsindifferent aspects,whereFCEVsappearedtobebetter thanBEVsinmanyways; thiscomparison isshownin Figure8. In thisfigure,differentcostsandcostassociated issuesofBEVandFCEV:weight, required storagevolume, initialGHGemission, requirednaturalgasenergy, requiredwindenergy, incremental costs, fueling infrastructurecostpercar, fuel costperkilometer,andincremental lifecyclecostareall 6