再生与不可再生能源(英文).ppt

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1、IntegratedScienceRenewableandNonrenewableenergysourcesIntroductionofsourcesofenergyNon-Renewable1.FossilFuels2.NuclearRenewable1.Wind2.Solar3.Tidal4.Hydropower5.GeothermalNon-Renewableenergysources:1.FossilFuelsWhatarefossilfuels?Afuelisanysubstanceusedasasourceofenergy,includingheating,transport,el

2、ectricitygenerationandotheruses.Mostoftheworldsenergyisprovidedbytheburningoffossilfuels(化石燃料).Coal,Oil and Gas are called fossil fuels”becausethey are natural combustible substances formedoriginallyfromdeadplantsandanimals.Themajorfossilfuelsarecoal(煤),petroleum(石油)andnaturalgas(天然氣).Fossils fuels

3、are non-renewable(非再生能源)energy sources.This is because fossil fuels take millions of years to form.Once they are used up they can never be replaced.WorldFuelResourcesPetroleumorOilNaturalGasCoalPowerreserves130billiontonnes158billioncubicmetres950billiontonnesTotalusedin19902.2billiontonnes1.5billio

4、ncubicmetres2.2billiontonnesFrom the above table,the present worlds estimated oil reserves may be used up in the next 50 to 60 years.CoalCoalistheplants,thatgrewinswampyareasabout300millionsago,diedtoformlayersofdecayingmaterial.Heat,pressureandtheactionofbacteriachangedthedecayingplantsintocoal.How

5、itworks:Coaliscrushedtoafinedustandburnt.How is coal used?Today,about70%ofthetotalcoalminedisburnedinpowerstation.Coal Education(http:/www.coaleducation.org/)Petroleum1.How was petroleum formed?Petroleumwasformedfromsmallseaanimalsandplantsthatlivedmillionsofyearsago.Aftertheydied,heat;pressure;andt

6、heactionofbacteriachangedtheremainsintooil.Theoilformedwasthentrappedassmalldropsinsidetheporesofrocks.Petroleum(http:/www.petroleum.co.uk/)How is petroleum used?Thethickcrudeoilthatcomesfromthegroundisacomplexmixtureofcompounds.Itisnecessarytoseparatethecompounds.Theseparatedsubstanceshavetwomainus

7、es:assourcesofusefulfuels.e.g.petrolasrawmaterialstomakeotherproducts.e.g.plastics,detergents.ProductsMadefromaBarrelofCrudeOilProductsMadefromaBarrelofCrudeOilNaturalGasNaturalgasisfoundtogetherwithoilandsometimeswithcoal.ThegasconsistsmainlyofmethaneCH4.Natural Gas(http:/www.naturalgas.org/)Source

8、:www.naturalgas.orgInsomecountries,thegasiscarriedbypipestohomesandfactoriesforheatingandcooking.HOWNATURALGASISSTOREDANDDELIVEREDHow is petroleum used?TheadvantageanddisadvantagesofusingfossilfuelAdvantagesVerylargeamountsofelectricitycanbegeneratedinoneplaceusingcoal,fairlycheaply.Transportingoila

9、ndgastothepowerstationsiseasy.Gas-firedpowerstationsareveryefficient.Afossil-fuelledpowerstationcanbebuiltalmostanywhereDisadvantagesPollutionBurninganyfossilfuelproducescarbondioxide,whichcontributestothegreenhouseeffect,warmingtheEarth.Burningcoalproducesmorecarbondioxidethanburningoilorgas.Italso

10、producessulphurdioxide,agasthatcontributestoacidrain.Wecanreducethisbeforereleasingthewastegasesintotheatmosphere.Miningcoalcanbedifficultanddangerous.Stripminingdestroyslargeareasofthelandscape.Non-Renewableenergysources:2.NuclearEnergyWhatareNuclearPower?Nuclear powerisgeneratedusingUranium,whichi

11、sametalminedinvariouspartsoftheworld.Somemilitaryshipsandsubmarineshavenuclearpowerplantsforengines.Nuclearpowerproducesaround11%oftheworldsenergyneeds,andproduceshugeamountsofenergyfromsmallamountsoffuel,withoutthepollutionthatyoudgetfromburningfossilfuelsHowitworksNuclearpowerstationsworkinprettym

12、uchthesamewayasfossilfuel-burningstations,exceptthatachainreactioninsideanuclearreactormakestheheatinstead.ThereactorusesUraniumrodsasfuel,andtheheatisgeneratedbynuclearfission.Neutronssmashintothenucleusoftheuraniumatoms,whichsplitroughlyinhalfandreleaseenergyintheformofheat.Carbondioxidegasispumpe

13、dthroughthereactortotaketheheataway,andthehotgasthenheatswatertomakesteam.Thesteamdrivesturbineswhichdrivegenerators.Modernnuclearpowerstationsusethesametypeofturbinesandgeneratorsasconventionalpowerstations.AdvantagesNuclearpowercostsaboutthesameascoal,soitsnotexpensivetomake.Doesnotproducesmokeorc

14、arbondioxide,soitdoesnotcontributetothegreenhouseeffect.Produceshugeamountsofenergyfromsmallamountsoffuel.Producessmallamountsofwaste.DisadvantagesItisvery,verydangerous.Itmustbesealedupandburiedformanyyearstoallowtheradioactivitytodieaway.Itisreliable,butalotofmoneyhastobespentonsafety-ifitdoesgowr

15、ong,anuclearaccidentcanbeamajordisaster.Peopleareincreasinglyconcernedaboutthesafety.Renewableenergysources:1.WindIntroductionWeveusedthewindasanenergysourceforalongtime.WindpowerwasusedintheMiddleAges,inEurope,togrindcorn,whichiswherethetermwindmillcomesfrom.HowitworksThewindblowsthepropellorround,

16、whichturnsageneratortoproduceelectricity.Themoretowers,themorewind,andthelargerthepropellors,themoreelectricitywecanmake.Itsonlyworthbuildingwindfarmsinplacesthathavestrong,steadywinds,althoughboatsandcaravansincreasinglyhavesmallwindgeneratorstohelpkeeptheirbatteriescharged.AdvantagesWindisfree,win

17、dfarmsneednofuel.Producesnowasteorgreenhousegases.Thelandbeneathcanusuallystillbeusedforfarming.Windfarmscanbetouristattractions.Agoodmethodofsupplyingenergytoremoteareas.DisadvantagesThewindisnotalwayspredictable-somedayshavenowind.Suitableareasforwindfarmsareoftennearthecoast,wherelandisexpensive.

18、Somepeoplefeelthatcoveringthelandscapewiththesetowersisunsightly.Cankillbirds-migratingflockstendtolikestrongwinds.Canaffecttelevisionreceptionifyoulivenearby.Canbenoisy.Renewableenergysources:2.SolarPowerIntroductionWeveusedtheSunfordryingclothesandfoodforthousandsofyears,butonlyrecentlyhavewebeena

19、bletouseitforgeneratingpower.JustthetinyfractionoftheSunsenergythathitstheEarth(aroundahundredthofamillionthofapercent)isenoughtomeetallourpowerneedsmanytimesover.Infact,everyminute,enoughenergyarrivesattheEarthtomeetourdemandsforawholeyear-ifonlywecouldharnessitproperly.HowitworksTherearetwomainway

20、sthatweusetheSunsenergy:-1.SolarCells-thatconvertlightdirectlyintoelectricity.2.Solarwaterheating,-whereheatfromtheSunisusedtoheatwateringlasspanelsonyourroof.AdvantagesSolarenergyisfree-itneedsnofuelandproducesnowasteorpollution.Insunnycountries,solarpowercanbeusedwherethereisnoeasywaytogetelectric

21、itytoaremoteplace.Handyforlow-powerusessuchassolarpoweredgardenlightsandbatterychargersDisadvantagesDoesntworkatnight.Veryexpensivetobuildsolarpowerstations.Solarcellscostagreatdealcomparedtotheamountofelectricitytheyllproduceintheirlifetime.Canbeunreliableunlessyoureinaverysunnyclimate.IntheUnitedK

22、ingdom,solarpowerisntmuchuseexceptforlow-powerapplications,asyouneedaverylargeareaofsolarpanelstogetadecentamountofpower.Renewableenergysources:3.TidalPowerIntroductionThetidemovesahugeamountofwatertwiceeachday,andharnessingitcouldprovideagreatdealofenergy-around20%ofBritainsneeds.Althoughtheenergys

23、upplyisreliableandplentiful,convertingitintousefulelectricalpowerisnoteasy.ThereareeightmainsitesaroundBritainwheretidalpowerstationscouldusefullybebuilt,includingtheSevern,Dee,SolwayandHumberestuaries.Onlyaround20sitesintheworldhavebeenidentifiedaspossibletidalpowerstations.Howitworks:TidalBarrages

24、Theseworkratherlikeahydro-electricscheme,exceptthatthedamismuchbigger.Ahugedam(calledabarrage)isbuiltacrossariverestuary.Whenthetidegoesinandout,thewaterflowsthroughtunnelsinthedam.AdvantagesOnceyouvebuiltit,tidalpowerisfree.Itproducesnogreenhousegasesorotherwaste.Itneedsnofuel.Itproduceselectricity

25、reliably.Notexpensivetomaintain.Tidesaretotallypredictable.DisadvantagesAbarrageacrossanestuaryisveryexpensivetobuild,andaffectsaverywidearea-theenvironmentischangedformanymilesupstreamanddownstream.Manybirdsrelyonthetideuncoveringthemudflatssothattheycanfeed.Therearefewsuitablesitesfortidalbarrages

26、.Onlyprovidespowerforaround10hourseachday,whenthetideisactuallymovinginorout.Renewableenergysources:4.HydropowerIntroductionWehaveusedrunningwaterasanenergysourceforthousandsofyears,mainlytogrindcorn.Thefirstuseofwatertogenerateelectricitywasin1882ontheFoxriver,intheUSA,whichproducedenoughpowertolig

27、httwopapermillsandahouse.Nowadaystherearemanyhydro-electricpowerstations,providingaround20%oftheworldselectricity.Thenamecomesfromhydro,theGreekwordforwater.HowitworksAdamisbuilttotrapwater,usuallyinavalleywherethereisanexistinglake.Waterisallowedtoflowthroughtunnelsinthedam,toturnturbinesandthusdri

28、vegenerators.Noticethatthedamismuchthickeratthebottomthanatthetop,becausethepressureofthewaterincreaseswithdepth.AdvantagesOncethedamisbuilt,theenergyisvirtuallyfree.Nowasteorpollutionproduced.Muchmorereliablethanwind,solarorwavepower.Watercanbestoredabovethedamreadytocopewithpeaksindemand.Hydro-ele

29、ctricpowerstationscanincreasetofullpowerveryquickly,unlikeotherpowerstations.Electricitycanbegeneratedconstantly.DisadvantagesThedamsareveryexpensivetobuild.However,manydamsarealsousedforfloodcontrolorirrigation,sobuildingcostscanbeshared.Buildingalargedamwillfloodaverylargeareaupstream,causingprobl

30、emsforanimalsthatusedtolivethere.Findingasuitablesitecanbedifficult-theimpactonresidentsandtheenvironmentmaybeunacceptable.Waterqualityandquantitydownstreamcanbeaffected,whichcanhaveanimpactonplantlifeRenewableenergysources:5.GeothermalIntroductionThecentreoftheEarthisaround6000degressCelsius-hoteno

31、ughtomeltrock.Evenafewkilometresdown,thetemperaturecanbeover250degreesCelsius.Ingeneral,thetemperaturerisesonedegreeCelsiusforevery36metresyougodown.Involcanicareas,moltenrockcanbeveryclosetothesurface.Geothermalenergyhasbeenusedforthousandsofyearsinsomecountriesforcookingandheating.Thenamegeotherma

32、lcomesfromtwoGreekwords:geomeansEarthandthermalmeansheat.HowitworksHotrocksundergroundheatwatertoproducesteam.Wedrillholesdowntothehotregion,steamcomesup,ispurifiedandusedtodriveturbines,whichdriveelectricgenerators.Theremaybenaturalgroundwaterinthehotrocksanyway,orwemayneedtodrillmoreholesandpumpwa

33、terdowntothem.AdvantagesGeothermalenergydoesnotproduceanypollution,anddoesnotcontributetothegreenhouseeffect.Thepowerstationsdonottakeupmuchroom,sothereisnotmuchimpactontheenvironment.Nofuelisneeded.Onceyouvebuiltageothermalpowerstation,theenergyisalmostfree.Itmayneedalittleenergytorunapump,butthisc

34、anbetakenfromtheenergybeinggeneratedDisadvantagesThebigproblemisthattherearenotmanyplaceswhereyoucanbuildageothermalpowerstation.Youneedhotrocksofasuitabletype,atadepthwherewecandrilldowntothem.Thetypeofrockaboveisalsoimportant,itmustbeofatypethatwecaneasilydrillthrough.Sometimesageothermalsitemayrunoutofsteam,perhapsfordecades.Hazardousgasesandmineralsmaycomeupfromunderground,andcanbedifficulttosafelydisposeof.ConclusionThoughtherearemoreandmorerenewableenergysources,savingenergyisveryimportant.