燃煤电厂(Coal-fired power plants)

时间:2021-12-16 08:41:23 考研英语作文

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theinventionoftheincandescentlightbulbbythomasa.edisonin1879createdademandforacheap,readilyavailablefuelwithwhichtogeneratelargeamountsofelectricpower.coalseemedtofitthebill,anditfueledtheearliestpowerstations.(whichweresetupattheendofthenineteenthcenturybyedisonhimself).

asmorepowerplantswereconstructedthroughoutthecountry,therelianceoncoalincreasedthroughoutthecountry,therelianceoncoalincreased.sincethefirstworldwar,coal-firedpowerplantshadacombinedintheunitedstateseachyear.in1986suchplantshadacombinedgeneratingcapacityof289,000megawattsandconsumed83percentofthenearly900milliontonsofcoalminedinthecountrythatyear.

giventheuncertaintyinthefuturegrowthofthenearly900milliontonsofcoalminedinthecountrythatyear.giventheuncertaintyinthefuturegrowthofnuclearpowerandinthesupplyofoilandnaturalgas,coal-firedpowerplantscouldwellprovideupto70percentoftheelectricpowerintheunitedstatesbytheendofthecentury.

yet,inspiteofthefactthatcoalhaslongbeenasourceofelectricityandmayremainonformanyyears(coalrepresentsabout80percentofunitedstatesfossil-fuelreserves),ithasactuallyneverbeenthemostdesirablefossilfuelforpowerplants.coalcontainslessenergyperunitofweightthanweightthannaturalgasoroil;itisdifficulttotransport,anditisassociatedwithahostofenvironmentalissues,amongthemacidrain.sincethelate1960'sproblemsofemissioncontrolandwastedisposalhavesharplyreducedtheappealofcoal-firedpowerplants.thecostofamelioratingtheseenvironmentproblemsalongwiththerisingcostofbuildingafacilityaslargeandcomplexasacoal-firedpowerplant,havealsomadesuchplantslessattractivefromapurelyeconomicperspective.

changesinthetechnologicalbaseofcoal-firedpowerplantscouldrestoretheirattractiveness,however.whereassomeofthesechangesareintendedmainlytoincreasetheproductivityofexistingplants,completelynewtechnologiesforburningcoalcleanlyarealsobeingdeveloped.