【文档说明】四川省成都七中高一英语外研版必修四素材（文章）Module 1 Wind Energy .doc，共(4)页，37.000 KB，由小赞的店铺上传

转载请保留链接：https://www.doc5u.com/view-48e740160ad465e3c6543088622e6904.html

以下为本文档部分文字说明：

WindEnergy--EnergyfromMovingAirWindissimpleairinmotion.Itiscausedbytheunevenheatingoftheearthsurfacebythesun.Sincetheearthsurfaceismadeof

verydifferenttypesoflandandwater,itabsorbsthesunheatatdifferentrates.Duringtheday,theairabovethelandheatsupmorequicklythantheairoverwat

er.Thewarmairoverthelandexpandsandrises,andtheheavier,coolerairrushesintotakeitsplace,creatingwinds.Atnight,thewindsarereversedbecaus

etheaircoolsmorerapidlyoverlandthanoverwater.Inthesameway,thelargeatmosphericwindsthatcircletheeartharecreatedbecausethelandneartheearth'

sequatorisheatedmorebythesunthanthelandneartheNorthandSouthPoles.Today,windenergyismainlyusedtogenerateelect

ricity.Windiscalledarenewableenergysourcebecausethewindwillblowaslongasthesunshines.TheHistoryofWindSinceancienttimes,peoplehaveharnessed

thewindsenergy.Over5,000yearsago,theancientEgyptiansusedwindtosailshipsontheNileRiver.Later,peoplebuiltwindmillstogrindwheatandother

grains.TheearliestknownwindmillswereinPersia(Iran).Theseearlywindmillslookedlikelargepaddlewheels.Centurieslater,thepeopleofHolla

ndimprovedthebasicdesignofthewindmill.Theygaveitpropeller-typeblades,stillmadewithsails.Hollandisfamousforitswindmills.A

mericancolonistsusedwindmillstogrindwheatandcorn,topumpwater,andtocutwoodatsawmills.Aslateasthe1920s,Ameri

cansusedsmallwindmillstogenerateelectricityinruralareaswithoutelectricservice.Whenpowerlinesbegantotransportele

ctricitytoruralareasinthe1930s,localwindmillswereusedlessandless,thoughtheycanstillbeseenonsomeWesternranches.Theoilshortag

esofthe1970schangedtheenergypictureforthecountryandtheworld.Itcreatedaninterestinalternativeenergysour

ces,pavingthewayforthere-entryofthewindmilltogenerateelectricity.Intheearly1980swindenergyreallytookoffinCalifornia,partlybecause

ofstatepoliciesthatencouragedrenewableenergysources.Supportforwinddevelopmenthassincespreadtootherstates

,butCaliforniastillproducesmorethantwiceasmuchwindenergyasanyotherstate.ThefirstoffshorewindparkintheUnitedStatesisplannedforan

areaoffthecoastofCapeCod,Massachusetts(readanarticleabouttheCapeCodWindProject).HowWindMachinesWorkLikeoldfashionedwin

dmills,todaywindmachinesusebladestocollectthewindkineticenergy.Windmillsworkbecausetheyslowdownthespeedofthewind.Thewindflowsovertheai

rfoilshapedbladescausinglift,liketheeffectonairplanewings,causingthemtoturn.Thebladesareconnectedtoadri

veshaftthatturnsanelectricgeneratortoproduceelectricity.Withthenewwindmachines,thereisstilltheproblemofw

hattodowhenthewindisblowing.Atthosetimes,othertypesofpowerplantsmustbeusedtomakeelectricity.WindPowerPlanWindpowerplants,orwi

ndfarmsastheyaresometimescalled,areclustersofwindmachinesusedtoproduceelectricity.Awindfarmusuallyhasdozensofwindmachinesscattere

doveralargearea.TheBigSpringWindPowerProjectinTexashas46windturbinesthatgenerateenoughelectricitytopower7,300homes.Unlikepowerplan

ts,manywindplantsarenotownedbypublicutilitycompanies.Insteadtheyareownedandoperatedbybusinesspeoplewhoselltheelectricityproducedonthewindfa

rmtoelectricutilities.TheseprivatecompaniesareknownasIndependentPowerProducers.Operatingawindpowerplantisnotassimpleasjustbuildingawindmilli

nawindyplace.Windplantownersmustcarefullyplanwheretolocatetheirmachines.Oneimportantthingtoconsiderishowfastandhowmuchthewindblows.Asarule,windspee

dincreaseswithaltitudeandoveropenareaswithnowindbreaks.Goodsitesforwindplantsarethetopsofsmooth,roundedhills,openplainsorshoreline

s,andmountaingapsthatproducewindfunneling.Windspeedvariesthroughoutthecountry.Italsovariesfromseasontoseason.InTehachapi,California,thewindbl

owsmorefromAprilthroughOctoberthanitdoesinthewinter.ThisisbecauseoftheextremeheatingoftheMojaveDesertduringthesummermonths.Thehotairoverthedesertri

ses,andthecooler,denserairabovethePacificOceanrushesthroughtheTehachapimountainpasstotakeitsplace.InastatelikeMontana,ontheother

hand,thewindblowsmoreduringthewinter.Fortunately,theseseasonalvariationsareagoodmatchfortheelectricitydemandsoftheregions.InCalifornia,peopleuse

moreelectricityduringthesummerforairconditioners.InMontana,peopleusemoreelectricityduringthewintermonthsforheating.W

indProductionAlltogether,windmachinesintheUnitedStatesgenerate17billionkWhperyearofelectricity,enoughtoserve1.6millionhouseholds.Thisise

noughelectricitytopoweracitythesizeofChicago,butitisonlyasmallfractionofthenation'stotalelectricityproduction,about0.

4percent.Theamountofelectricitygeneratedfromwindhasbeengrowingfastinrecentyears,triplingsince1998.Newtechnolo

gieshavedecreasedthecostofproducingelectricityfromwind,andgrowthinwindpowerhasbeenencouragedbytaxbreaksforrenewableenergyandgreenpricingprogram

s.Manyutilitiesaroundthecountryoffergreenpricingoptionsthatallowcustomersthechoicetopaymoreforelectricity

thatcomesfromrenewablesources.Windmachinesgenerateelectricityin30differentstates.Thestateswiththemostwindprodu

ctionareCalifornia,Texas,Minnesota,Iowa,andWyoming.TheUnitedStatesranksthirdintheworldinwindpowercapacity,behindGermanyandSpa

in.MostofthewindpowerplantsintheworldarelocatedinEuropeandintheUnitedStateswheregovernmentprogramshavehelpedsupportwindpowe

rdevelopment.WindandtheEnvironmentInthe1970s,oilshortagespushedthedevelopmentofalternativeenergysources.

Inthe1990s,thepushcamefromarenewedconcernfortheenvironmentinresponsetoscientificstudiesindicatingpotentialchangestotheglobalclimateiftheuseoffossi

lfuelscontinuestoincrease.Windenergyoffersaviable,economicalalternativetoconventionalpowerplantsinmanyareasofthecountry.Wi

ndisacleanfuel;windfarmsproducenoairorwaterpollutionbecausenofuelisburned.Themostseriousenvironmentaldrawbackstowindmachinesmaybetheirn

egativeeffectonwildbirdpopulationsandthevisualimpactonthelandscape.Tosome,theglisteningbladesofwindmillsonthehorizonareaneyesore;toothers

,theyareabeautifulalternativetoconventionalpowerplants.