小学高年级科普英语

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1、CleanEnergysCleanenergiesinclude:solarpowerandlimitedsupplyofotherpowersourcessuchasfossilfuelsarerealized.Itisalreadyinwidespreadusewhereothersuppliesofpowerareabsentsuchasinremotelocationsandinspace.AstheEarthorbitstheSun,itreceivesapproximately1,400W/m²ofenerg

2、y,asmeasureduponasurfacekeptnormal(atarightangle)totheSun(thisnumberisreferredtoasthesolarconstant).Oftheenergyreceived,roughly19%isabsorbedbytheatmosphere,whilecloudsonaveragereflectafurther35%ofthetotalenergy.Thegenerallyacceptedstandardis1020wattspersquaremete

3、ratsealevelAfterpassingthroughtheEarth'satmosphere,mostofthesun'senergyisintheformofvisibleandultravioletlight.Plantsusesolarenergytocreatechemicalenergythroughphotosynthesis.Weusethisenergywhenweburnwoodorfossilfuelsorwhenweconsumetheplantsasasourceoffood.Windpo

4、werWindpoweristhekineticenergyofwind,ortheextractionofthisenergybywindturbines.Thisarticledealsmainlywiththeintricaciesoflarge-scaledeploymentofwindturbinestogenerateelectricity.WavepowerWavepowerreferstothecaptureofoceansurfacewaveenergytodousefulworkincludingel

5、ectricitygeneration,desalination,andfillingareservoirwithwater.Wavepowerisaformofrenewableenergy.Thoughoftenco-mingled,wavepowerisphysiologicallydistinctfromthediurnalfluxoftidalpowerandthesteadygyreofoceancurrentswhicharepoweredbytheearth'srotation.Wavepowergene

6、rationisnotawidelyemployedtechnologywithonlyafewexperimentalsitesinexistence.SalinitygradientpowerSalinityGradientisatechnologythattakesadvantageoftheosmoticpressuredifferencesbetweensaltandfreshwater.Ifweplaceasemipermeablemembrane(likethatinareverseosmosisfilte

7、r)betweensealedbodiesofsaltwaterandfreshwater,thefreshwaterwillgraduallytravelthroughthefilterbyosmosis.ByexploitingthepressuredifferencebetweenthesetwobodiesofwaterwecanextractenergycommensuratetothedifferenceinpressureTidalpowerTidalpowerisameansofelectricityge

8、nerationachievedbycapturingtheenergycontainedinmovingwatermassduetotides.Twotypesoftidalenergycanbeextracted:kineticenergyofcurrentsduethetidesandpotentialener