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Unit8PowertothepeopleAlmostacenturyhasgonebysincehumansbeganexploitingacompellingnewwaytopowertheglobaleconomy.Theswitchtofossilfuelsprompted促使anexplosioninnovationeithersideofthe1900s.includingcreationssuchastheinternalcombustionengine.Suchtechnologieshavesinceprovidedthemeanstodriveourthirsty,energy-intensivemodernsocieties.Todaywestandatasimilarturningpoint.Solarpower,windturbinesandothersourcesofcleanpower---thepreserveofvisionaries有预见的人andenthusiastslittlemorethanadecadeago---arenowpoisedonthebrinkofthemainstream,helpedinnosmallpartbytheenvironmentaldeficienciesoffossilfuels.Theneedtocreatecleanenergyhasbecomeapressingconcernforpolicymakersandbigbusiness---nottomentiontheconsumer.Suchthinkingisfuelledbythegrowingrealizationthatallalongnaturehasprovidedready-mademeanstopowermoderncivilizations,namelythroughtheelements.Crucialadvancesinnewtechnologyhavetheseinexhaustiblesourcescheapertousewith,forexample,thecostofsolarenergyplungingbyupto98percentoverthepast20years.Intheory,theserenewableenergyresourcesareincongruouslarge.Thesunaloneprovidesthemeanstodeliver7,000timesourownenergyconsumption;blankingjust2.6percentoftheSaharadesertwithsolarcellscouldsupplyourentireneeds.Yetforallthisimpressivepotential,renewableenergycurrentlyproducesjusttwopercentofourtotalenergyoutput.However,asthecomputerindustrydiscoveredinthe1980s,rapidgrowthcanswiftlytransformaminoritysectorintoagiantcapableofdominatingourlives.Alreadycompaniesacrosstheglobearescrambling征服争夺tobecomethenextIntelorMicrosoftofthenewenergyrevolution.Ourhomes,cities,andworkplaces---ourlives---maybereshapedinwayswecanonlybegintoguessatthesolarcell,thewindfarmandtheelectriccarenterlargersectorsofthemarketplace.BlazingatrailThesun’scapabilitytopowertheplanetisphenomenal杰出的.Alreadyabillion-poundbusiness,projectionsindicateanannualgrowthrateforthenextdecadeof14percent.Butthepriceofsolartechnologyhasalwaysbeenitsbiggeststickingpoint,andthecostofsolarcellswillneedtofallbyupto50percentinordertofullycompetitivewithcoal-firedelectricity.Severalcompaniesarecurrentlydevelopinganewgenerationofwafer-thinphotovoltaic光电的solarpanelsthatwillslash大量削减costsstillfurther.Photovoltaics(pv)convertthesun’sheatintoelectricity,silentlyandwithoutpollution.Theyusesemi-conductorsthatsendoutelectronstheinstantsunlightreachesthem,triggering使触发引起theflowofelectricity.Thegreaterthevolumeofsunlight,themoreelectronsareemitted发射或发射出.Solarpowercouldprovidethousandsoftimesmoreenergythanweworldcurrentlyuses,theearthreceivinganunimaginablyhugeamountofenergywaybeyondthecapabilitiesoffossilfuelsornuclearfission.Infigures,thesun’scontinuouspowerinputstands数据at200wattsfollowedby15zeros.Itsusesareimpressivelyvaried.Solarcellsnowpowersatellites,mobilephones,televisionsets,highwaysignalsandwaterpumps.LastyeartheDutchsolarcarNunabroketheworldrecord---withanaveragespeedof91km/h---intheworldSolarchallenge,a3,010-kilometerraceacrossAustraliaforcarspoweredbythesun.Alookattheplanet’smostconspicuous明显的consumersrevealsthatsolarenergyisfinallybeginningtomakerealinroadsasanalternativeenergy.TheUSA’sMillionSolarRoofsInitiativeaimstoputamillionsolarsystemsontheroofsofcommercialandresidentialbuildingby2010.Inaddition,30statesnowhaveofficialpoliciesencouragingthedevelopmentofsolarenergywithfinancialincentivesforinvestmentintheuseofPVmodulesandcells.AdvocatesbelievethatPVcouldclaimtobethesimplestandmosteleganttechnologytoharnessthepowerofthesun,beingeasytoinstallandrequiringminimalmaintenance.Giventhisadvantages,thefutureofsolarphotovoltaicsappearsbright.TappingintowaterHarnessingthepowerofmovingwater,whetherthroughthenaturalrhythemsofthetideandoceanwavesorbymeansofmassiveartificialdams,offersanotherrenewableenergysourcewithamajorfuture.Wavepoweralonehasthepotentialtoprovideenoughpowertosupplyanestimated1.4millionhouseholdsinanindustrialsociety.However,theintrinsicdifficultiesinharnessing开发thestrengthofroughseashavecreatedmajorheadachesforengineers;twowave-powerstationsinScotlandandNorwayhavealreadyfallenvictimtothesea.Onceagainthough,thebiggesthurdleisfinancial,withconstructionofturbinesatseaexpensive,despitetheactualenergybeingplentifulandfree.Furtherdifficultiesarecausedbythefactthatwavesrefusetoflowinonedirection.Onesolutiontothisproblemhasbeentofitturbinesinachimney-typeseabedstructurethatcanbeorientedtofacethedirectionofenergy-givingwaves.Bycontrast,hydroelectricpoweriswellestablished,producingalmostaquarteroftheworld’selectricityandsupplyingmorethanonebillionpeoplewithpower.Hydropowerproducesenergyequivalentto3.6billionbarrelsofoilayear.Electricityisproducedbyfallingwaterpassingthroughaturbine;damsareoftenusedtoensurewatersupplycanbecontrolleddependingonthedemandforpower.Howevertheconstructionofmightydamsoftenhashugeenvironmentalimpactscausedbyhavingtofloodlargeareas,triggeringacutedamageexistinghabitats---thethreegorgesdamcurrentlyunderconstructioninchinawillsee632squarekilometersinundated洪水泛滥and1.1millionpeoplefacingresettlement.Suchobviousdeficiencies缺点aside,hydropoweroffersaclean,renewablesourceofenergythat