2024剑桥雅思讲义Short_Answer_Questions_Strategy_Practice.docx

IELTSADVANTAGEShortAnswerQuestionsStrategyPracticeAustralia'swindenergyresourcesWindisavastpotentialsourceofrenewableenergy.Windsaregeneratedbycomplexmechanismsinvolvingtherotationoftheearth,theheatcapacityofthesun,thecoolingeffectoftheoceansandpolaricecaps,temperaturegradientsbetweenlandandsea,andthephysicaleffectsofmountainsandotherobstacles.Windenergyisgeneratedbyconvertingwindcurrentsintootherformsofenergyusingawindturbine.Turbinesextractenergyfromthepassingairbyconvertingkineticenergyfromrotationalmovementviaarotor.Theeffectivenessofthisconversionatanygivensiteiscommonlymeasuredbyitsenergydensityor,alternatively,asacapacityfactor.Windenergyisprimarilyusedforelectricitygeneration,bothonsiteandfortransporttothegrid.Windenergyisalsousedtopumpborewater,particularlyinruralareas.Thewindenergyindustryisthefastestgrowingrenewableenergysourceinmanycountriesandisexpectedtocontinuetogrowrapidlyovertheperiodto2030.ProductionofwindenergyislargelyconcentratedinEuropeandtheUnitedStates.However,therehasalsobeenrapidgrowthinthewindenergyindustriesinChinaandIndia.Theworld'swindenergyresourceisestimatedtobeaboutonemillionGWfortotallandcoverage.Assumingonly1percentoftheareaisutilisedandallowanceismadeforthelowerloadfactorsofwindplants,thewindenergypotentialwouldcorrespondtoaroundtheworldtotalelectricitygenerationcapacity.Thewindiestareasaretypicallycoastalregionsofcontinentsatmid-tohighlatitudesandinmountainousregions.Locationswiththehighestwindenergypotentialincludethewesterlywindbeltsbetweenlatitudes35oand50o.ThisincludesthecoastalregionsofwesternandsouthernAustralia,NewZealand,southernSouthAmerica,andSouthAfricainthesouthernhemisphere,andnorthernandwesternEurope,andthenortheasternandwesterncoastsoftheUnitedStates.Theseregionsaregenerallycharacterisedbyhigh,relativelyconstantwindconditions,withaveragewindspeedsinexcessof6metrespersecond(ms)and,inplaces,morethan9ms.Regionswithhighwindenergypotentialarecharacterisedby: highaveragewindspeeds; windsthatareeitherconstantorcoincidingwithpeakenergyconsumptionperiods(duringthedayorevening); proximitytoamajorenergyconsumptionregion;IELTSADVANTAGEShortAnswerQuestionsStrategyPractice smoothlandscape,whichincreaseswindspeeds,andreducesthemechanicalstressonwindturbinecomponentsthatresultsfromvariableandturbulentwindconditionsassociatedwithroughlandscape.Becauseofwindvariability,theenergydensityatapotentialsite-commonlydescribedasitscapacityfactor-isgenerallyintherangeof20-40percent.Whilethemajorityofareasinlocationsconvenientforelectricitytransfertothegridarelocatedonshore,offshoresiteshavealsobeenidentifiedashavingsignificantpotentialforwindenergy,bothtotakeadvantageofincreasedwindspeedsandtoincreasethenumberofavailablesites.Offshorelocationsalsohelpreduceturbulenceand,hence,stressonmachinecomponents.TherehavebeenwindturbinesdeployedinshallowseasoffnorthernEuropeformorethanadecade.Offshoresitesareexpectedtomakeanincreasinglysignificantcontributiontoelectricitygenerationinsomecountries,notablyinEuropebecauseinEuropethereareincreasingdifficultiesingainingaccesstoonshoresites.Australiahassomeofthebestwindresourcesintheworld.Australia'swindenergyresourcesarelocatedmainlyinthesouthernpartsofthecontinent(whichlieinthepathofthewesterlywindflowknownasthe'roaring40s')andreachamaximumaroundBassStrait.Thelargestwindresourceisgeneratedbythepassageoflowpressureandassociatedfrontalsystems,whosenortherlyextentandinfluencedependsonthesizeofthefrontalsystem.WindsinnorthernAustraliaarepredominantlygeneratedbythemonsoonandtradewindsystems.Large-scaletopographysuchastheGreatDividingRangeineasternAustraliaexertsignificantsteeringeffectsonthewinds,channellingthemthroughmajorvalleysordeflectingorblockingthemfromotherareas.DeflectionofweakerfrontsfromfrontalrefractionaroundtherangesoftheDivideinsoutheasternAustraliacreateswindswithasoutherlycomponent('southerlybusters,)alongtheeastcoast.InadditiontotherefractionsbytopographyandheatlowsovernorthernAustralia,othermajorfactorsinfluencingwindresourcesareseasonalanddiurnalvariationinwindspeed.WindsarestrongestinwinterandspringinwesternandsouthernAustraliabutthemonthlybehaviourdiffersfromregiontoregion.Variationsinaveragemonthlywindspeedofupto15-20percentoverthelongtermannualaveragearenotuncommon.Theremaybesimilardailyvariationsatindividuallocations,withincreasedwindspeedsintheafternoon.Meso-scalemapsshowthatAustralia'sgreatestwindpotentialliesinthecoastalregionsofwestern,south-western,southernandsouth-easternAustralia.Coastalregionswithhighwindresources(windspeedsabove7.5ms)includethewestcoastsouthofSharkBaytoCapeLeeuwin,alongtheGreatAustralianBightandtheEyrePeninsulainSouthAustralia,towesternVictoriaandthewestcoastofTasmania.GoodwindresourcesextendhundredsofkilometresinlandandmanyofAustralia'swindfarms(currentandplanned)arelocatedsomedistancefromthecoast.InlandIELTSADVANTAGEShortAnswerQuestionsStrategyPracticeregionsofWesternAustralia,SouthAustraliaandwesternVictoriaallhavegoodwindresources.Areaswithhig