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1、HydrogenandFutureEnergySourcesWelearnedthatfossilfuelswereformedbeforeandduringthetimeofthedinosaurs-whenplantsandanimalsdied.Theirdecomposedremainsgraduallychangedovertheyearstoformcoal,oilandnaturalgas.Fossilfuelstookmillionsofyearstomake.Weareusingupthefuelsformedmo
2、rethan65millionyearsago.Theycan'tberenewed;theycan'tbemadeagain.Wecansavefossilfuelsbyconservingandfindingwaystoharnessenergyfromseemingly"endlesssources,"likethesunandthewind.Wecan'tusefossilfuelsforeverastheyareanon-renewableandfiniteresource.Somepeoplesuggestthatwes
3、houldstartusinghydrogen.Hydrogenisacolorless,odorlessgasthataccountsfor75percentoftheentireuniverse'smass.HydrogenisfoundonEarthonlyincombinationwithotherelementssuchasoxygen,carbonandnitrogen.Tousehydrogen,itmustbeseparatedfromtheseotherelements.Today,hydrogenisusedpr
4、imarilyinammoniamanufacturing,petroleumrefiningandsynthesisofmethanol.It'salsousedinNASA'sspaceprogramasfuelforthespaceshuttles,andinfuelcellsthatprovideheat,electricityanddrinkingwaterforastronauts.Fuelcellsaredevicesthatdirectlyconverthydrogenintoelectricity.Inthefut
5、ure,hydrogencouldbeusedtofuelvehicles(suchastheDaimlerChryslerNeCar4showninthepicturetotheright)andaircraft,andprovidepowerforourhomesandoffices.Hydrogencanbemadefrommoleculescalledhydrocarbonsbyapplyingheat,aprocessknownas"reforming"hydrogen.Thisprocessmakeshydrogenfr
6、omnaturalgas.Anelectricalcurrentcanalsobeusedtoseparatewaterintoitscomponentsofoxygenandhydrogeninaprocesscalledelectrolysis.Somealgaeandbacteria,usingsunlightastheirenergysource,giveoffhydrogenundercertainconditions.Hydrogenasafuelishighinenergy,yetamachinethatburnspu
7、rehydrogenproducesalmostzeropollution.NASAhasusedliquidhydrogensincethe1970stopropelrocketsandnowthespaceshuttleintoorbit.Hydrogenfuelcellspowertheshuttle'selectricalsystems,producingacleanby-product-purewater,whichthecrewdrinks.Youcanthinkofafuelcellasabatterythatisco
8、nstantlyreplenishedbyaddingfueltoit-itneverlosesitscharge.ToviewaFLASHvideoofhowafuelcellworks,gototheBallardPowerSys
