Reading(1)：TeachamantofishVIP专享VIP免费

HydrogenandFutureEnergySourcesWelearnedthatfossilfuelswereformedbeforeandduringthetimeofthedinosaurs-whenplantsandanimalsdied.Theirdecomposedremainsgraduallychangedovertheyearstoformcoal,oilandnaturalgas.Fossilfuelstookmillionsofyearstomake.Weareusingupthefuelsformedmorethan65millionyearsago.Theycan'tberenewed;theycan'tbemadeagain.Wecansavefossilfuelsbyconservingandfindingwaystoharnessenergyfromseemingly"endlesssources,"likethesunandthewind.Wecan'tusefossilfuelsforeverastheyareanon-renewableandfiniteresource.Somepeoplesuggestthatweshouldstartusinghydrogen.Hydrogenisacolorless,odorlessgasthataccountsfor75percentoftheentireuniverse'smass.HydrogenisfoundonEarthonlyincombinationwithotherelementssuchasoxygen,carbonandnitrogen.Tousehydrogen,itmustbeseparatedfromtheseotherelements.Today,hydrogenisusedprimarilyinammoniamanufacturing,petroleumrefiningandsynthesisofmethanol.It'salsousedinNASA'sspaceprogramasfuelforthespaceshuttles,andinfuelcellsthatprovideheat,electricityanddrinkingwaterforastronauts.Fuelcellsaredevicesthatdirectlyconverthydrogenintoelectricity.Inthefuture,hydrogencouldbeusedtofuelvehicles(suchastheDaimlerChryslerNeCar4showninthepicturetotheright)andaircraft,andprovidepowerforourhomesandoffices.Hydrogencanbemadefrommoleculescalledhydrocarbonsbyapplyingheat,aprocessknownas"reforming"hydrogen.Thisprocessmakeshydrogenfromnaturalgas.Anelectricalcurrentcanalsobeusedtoseparatewaterintoitscomponentsofoxygenandhydrogeninaprocesscalledelectrolysis.Somealgaeandbacteria,usingsunlightastheirenergysource,giveoffhydrogenundercertainconditions.Hydrogenasafuelishighinenergy,yetamachinethatburnspurehydrogenproducesalmostzeropollution.NASAhasusedliquidhydrogensincethe1970stopropelrocketsandnowthespaceshuttleintoorbit.Hydrogenfuelcellspowertheshuttle'selectricalsystems,producingacleanby-product-purewater,whichthecrewdrinks.Youcanthinkofafuelcellasabatterythatisconstantlyreplenishedbyaddingfueltoit-itneverlosesitscharge.ToviewaFLASHvideoofhowafuelcellworks,gototheBallardPowerSystemswebsite.FuelCellUsesFuelcellsareapromisingtechnologyforuseasasourceofheatandelectricityinbuildings,andasanelectricalpowersourceforvehicles.Autocompaniesareworkingonbuildingcarsandtrucksthatusefuelcells.Inafuelcellvehicle,anelectrochemicaldeviceconvertshydrogen(storedonboard)andoxygenfromtheairintoelectricity,todriveanelectricmotorandpowerthevehicle.Althoughtheseapplicationswouldideallyrunoffpurehydrogen,intheneartermtheyarelikelytobefueledwithnaturalgas,methanolorevengasoline.Reformingthesefuelstocreatehydrogenwillallowtheuseofmuchofourcurrentenergyinfrastructure-gasstations,naturalgaspipelines,etc.-whilefuelcellsarephasedin.Inthefuture,hydrogencouldalsojoinelectricityasanimportantenergycarrier.Anenergycarrierstores,movesanddeliversenergyinausableformtoconsumers.Renewableenergysources,likethesun,can'tproduceenergyallthetime.Thesundoesn'talwaysshine.Buthydrogencanstorethisenergyuntilitisneededandcanbetransportedtowhereitisneeded.Someexpertsthinkthathydrogenwillformthebasicenergyinfrastructurethatwillpowerfuturesocieties,replacingtoday'snaturalgas,oil,coal,andelectricityinfrastructures.Theyseeanew"hydrogeneconomy"toreplaceourcurrent"fossilfuel-basedeconomy,"althoughthatvisionprobablywon'thappenuntilfarinthefuture.SolarPowerSatellitesOnesuggestionforenergyinthefutureistoputhugesolarpowersatellitesintoorbitar...