environmentallyfriendlyrenewableenergy

　　环保可再生能源

　　PresidentJimmyCarter,inanaddresstothenation,proposedthatbytheendofthecentury,20%oftheelectricityusedintheU.S.shouldbederivedfromthesun.Atthetimehemadethestatement,itseemedlikeanenvironmentallyfriendlyvisionthatcouldbeaccomplished;however,asweentertheyear2002,solarandwindgeneratedpoweronlysupplyabout2%ofthenation’sdemandforelectricity.Inthepast,thebarrierthatseparatedwindandsolarenergyfromfossilfuelenergywascostefficiency.Recently,manyadvancesintechnologymayhavebrokenthatcostbarrier,anditmaynolongerbeanobstacleforindustryandconsumerstohavecheaperaccesstorenewableenergy.Someofficialscommentthatthepricesofrenewableenergyareabout1/8ofwhattheywere12yearsago,andtheyexpectsolarandwindpoweredenergytobethefastestgrowingenergysourceforindividualbuildingsandhousesoverthenextfewdecades.Infact,insomeareas,windfarmsaregrowingindemandbecausetheyarecheapertoaddthannon-renewablefossilfuelenergysources.Someenergyanalystsareoptimisticthatbytheyear2020,windandsolarenergymaysupply10%ofthenation’senergydemands.Otherrenewableenergysourcessuchashydroelectricdams,whichcurrentlygenerateabout8–10%ofthenationselectricity,arenotexpectedtogrowindemand.Althoughhydroelectricityisviewedasacleanenergysource,itdoescomeatahighpriceofalteringthenaturalflowofriverwater,nearbyplantandwildlifehabitats,andforcingsomefishspeciesnearextinction.TheworksheetincludestheURLfortheU.S.DepartmentofEnergywebsite.

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