資源描述:
《文章Wind Energy.doc》由會員上傳分享,免費(fèi)在線閱讀,更多相關(guān)內(nèi)容在教育資源-天天文庫。
1、WindEnergy--EnergyfromMovingAirWindissimpleairinmotion.Itiscausedbytheunevenheatingoftheearthsurfacebythesun.Sincetheearthsurfaceismadeofverydifferenttypesoflandandwater,itabsorbsthesunheatatdifferentrates.Duringtheday,theairabovethelandheatsupmorequicklythanth
2、eairoverwater.Thewarmairoverthelandexpandsandrises,andtheheavier,coolerairrushesintotakeitsplace,creatingwinds.Atnight,thewindsarereversedbecausetheaircoolsmorerapidlyoverlandthanoverwater.Inthesameway,thelargeatmosphericwindsthatcircletheeartharecreatedbecause
3、thelandneartheearth'sequatorisheatedmorebythesunthanthelandneartheNorthandSouthPoles.Today,windenergyismainlyusedtogenerateelectricity.Windiscalledarenewableenergysourcebecausethewindwillblowaslongasthesunshines.TheHistoryofWindSinceancienttimes,peoplehaveharne
4、ssedthewindsenergy.Over5,000yearsago,theancientEgyptiansusedwindtosailshipsontheNileRiver.Later,peoplebuiltwindmillstogrindwheatandothergrains.TheearliestknownwindmillswereinPersia(Iran).Theseearlywindmillslookedlikelargepaddlewheels.Centurieslater,thepeopleofH
5、ollandimprovedthebasicdesignofthewindmill.Theygaveitpropeller-typeblades,stillmadewithsails.Hollandisfamousforitswindmills.Americancolonistsusedwindmillstogrindwheatandcorn,topumpwater,andtocutwoodatsawmills.Aslateasthe1920s,Americansusedsmallwindmillstogenerat
6、eelectricityinruralareaswithoutelectricservice.Whenpowerlinesbegantotransportelectricitytoruralareasinthe1930s,localwindmillswereusedlessandless,thoughtheycanstillbeseenonsomeWesternranches.Theoilshortagesofthe1970schangedtheenergypictureforthecountryandtheworl
7、d.Itcreatedaninterestinalternativeenergysources,pavingthewayforthere-entryofthewindmilltogenerateelectricity.Intheearly1980swindenergyreallytookoffinCalifornia,partlybecauseofstatepoliciesthatencouragedrenewableenergysources.Supportforwinddevelopmenthassincespr
8、eadtootherstates,butCaliforniastillproducesmorethantwiceasmuchwindenergyasanyotherstate.ThefirstoffshorewindparkintheUnitedStatesisplannedforanareaoffthecoastofCapeCod,Massa