Wind Energy.docx

WindEnergy-EnergyfromMovingAirWindissimpleairinmotion.Itiscausedbytheunevenheatingoftheearthsurfacebythesun.Sincetheearthsurfaceismadeofverydifferenttypesoflandandwater,itabsorbsthesunheatatdifferentrates.Duringtheday,theairabovethelandheatsupmorequicklythantheairoverwater.Thewarmairoverthelandexpandsandrises,andtheheavier,coolerairrushesintotakeitsplace,creatingwinds.Atnight,thewindsarereversedbecausetheaircoolsmorerapidlyoverlandthanoverwater.Inthesameway,thelargeatmosphericwindsthatcircletheeartharecreatedbecausethelandneartheearth,sequatorisheatedmorebythesunthanthelandneartheNorthandSouthPoles.Today,windenergyismainlyusedtogenerateelectricity.Windiscalledarenewableenergysourcebecausethewindwillblowaslongasthesunshines.TheHistoryofWindSinceancienttimes,peoplehaveharnessedthewindsenergy.Over5,000yearsago,theancientEgyptiansusedwindtosailshipsontheNileRiver.Later,peoplebuiltwindmillstogrindwheatandothergrains.TheearliestknownwindmillswereinPersia(Iran).Theseearlywindmillslookedlikelargepaddlewheels.Centurieslater,thepeopleofHollandimprovedthebasicdesignofthewindmill.Theygaveitpropeller-typeblades,stillmadewithsails.Hollandisfamousforitswindmills.Americancolonistsusedwindmillstogrindwheatandcorn,topumpwater,andtocutwoodatsawmills.Aslateasthe1920s,Americansusedsmallwindmillstogenerateelectricityinruralareaswithoutelectricservice.Whenpowerlinesbegantotransportelectricitytoruralareasinthe1930s,localwindmillswereusedlessandless,thoughtheycanstillbeseenonsomeWesternranches.Theoilshortagesofthe1970schangedtheenergypictureforthecountryandtheworld.Itcreatedaninterestinalternativeenergysources,pavingthewayforthere-entryofthewindmilltogenerateelectricity.Intheearly1980swindenergyreallytookoffinCalifornia,partlybecauseofstatepoliciesthatencouragedrenewableenergysources.Supportforwinddevelopmenthassincespreadtootherstates,butCaliforniastillproducesmorethantwiceasmuchwindenergyasanyotherstate.ThefirstoffshorewindparkintheUnitedStatesisplannedforanareaoffthecoastofCapeCod,Massachusetts(readanarticleabouttheCapeCodWindProject).HowWindMachinesWorkLikeoldfashionedwindmills,todaywindmachinesusebladestocollectthewindkineticenergy.Windmillsworkbecausetheyslowdownthespeedofthewind.Thewindflowsovertheairfoilshapedbladescausinglift,liketheeffectonairplanewings,causingthemtoturn.Thebladesareconnectedtoadriveshaftthatturnsanelectricgeneratortoproduceelectricity.Withthenewwindmachines,thereisstilltheproblemofwhattodowhenthewindisblowing.Atthosetimes,othertypesofpowerplantsmustbeusedtomakeelectricity.WindPowerPlanWindpowerplants,orwindfarmsastheyaresometimescalled,areclustersofwindmachinesusedtoproduceelectricity.Awindfarmusuallyhasdozensofwindmachinesscatteredoveralargearea.TheBigSpringWindPowerProjectinTexashas46windturbinesthatgenerateenoughelectricitytopower7,3homes.Unlikepowerplants,manywindplantsarenotownedbypublicutilitycompanies.Insteadtheyareownedandoperatedbybusinesspeoplewhoselltheelectricityproducedonthewindfarmtoelectricutilities.TheseprivatecompaniesareknownasIndependentPowerProducers.Operatingawindpowerplantisnotassimpleasjustbuildingawindmillinawindyplace.Windplantownersmustcarefullyplanwheretolocatetheirmachines.Oneimportantthingtoconsiderishowfastandhowmuchthewindblows.Asarule,windspeedincreaseswithaltitudeandoveropenareaswithnowindbreaks.Goodsitesforwindplantsarethetopsofsmooth,roundedhills,openplainsorshorelines,andmountaingapsthatproducewindfunneling.Windspeedvariesthroughoutthecountry.Italsovariesfromseasontoseason.InTehachapi,California,thewindblowsmorefromAprilthroughOctoberthanitdoesinthewinter.ThisisbecauseoftheextremeheatingoftheMojaveDesertduringthesummermonths.Thehotairoverthedesertrises,andthecooler,denserairabovethePacificOceanrushesthroughtheTehachapimountainpasstotakeitsplace.InastatelikeMontana,ontheotherhand,thewindblowsmoreduringthewinter.Fortunately,theseseasonalvariationsareagoodmatchfortheelectricitydemandsoftheregions.InCalifornia,peopleusemoreelectricityduringthesummerforairconditioners.InMontana,peopleusemoreelectricityduringthewintermonthsforheating.WindProductionAlltogether,windmachinesintheUnitedStatesgenerate17billionkWhperyearofelectricity,enoughtoserve1.6millionhouseholds.ThisisenoughelectricitytopoweracitythesizeofChicago,butitisonlyasmallfractionofthenation,stotalelectricityproduction,about0.4percent.Theamountofelectricitygeneratedfromwindhasbeengrowingfastinrecentyears,triplingsince1998.Newtechnologieshavedecreasedthecostofproducingelectricityfromwind,andgrowthinwindpowerhasbeenencouragedbytaxbreaksforrenewableenergyandgreenpricingprograms.Manyutilitiesaroundthecountryoffergreenpricingoptionsthatallowcustomersthechoicetopaymoreforelectricitythatcomesfromrenewablesources.Windmachinesgenerateelectricityin30differentstates.ThestateswiththemostwindproductionareCalifornia,Texas,Minnesota,Iowa,andWyoming.TheUnitedStatesranksthirdintheworldinwindpowercapacity,behindGermanyandSpain.MostofthewindpowerplantsintheworldarelocatedinEuropeandintheUnit