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1、NaturalgasDifferenceEngine:Fuelforthefuture?May27th2013,21:13byN.V.
2、LOSANGELES··TweetAMERICA’Sunexpected,andmostwelcome,bonanzaofnaturalgasfromitsvastshaledepositsseemstobedoingasmuchtoreducepollutionasmanyoftheeffortsintroducedovertheyearstorestrictemissionsfromvehicles,powerstationsandot
3、hersources.Thebiggestbreakthroughtheenergyindustryhasseenindecades,hydraulicfracturing(“fracking”)combinedwithhorizontaldrilling,hasreleasedunprecedentedquantitiesofgasfromthisshale.Asaconsequence,thespotpriceofdomesticallyproducednaturalgashastumbledfromahighofover$12permillionBritishTher
4、malUnitsin2008tolessthan$2in2012,beforesettlingataround$4today(amillionBTUsisroughlyequivalenttoagigajouleofenergy).Increasinguseofthischeap,cleangasmeanspowerstationsacrossthecountryhavereducedtheircarbondioxideemissionstolevelsnotseensince1992—despiteservingapopulationthathasgrownbyalmos
5、taquartersincethen.Onapercapitabasis,carbondioxideemissionsfrompowerstationsarenowattheirlowestsincePresidentEisenhowerleftofficein1961.Thisisbecause,whenpurgedofimpurities,naturalgas(whichismoreorlesspuremethane)isthecleanestfossilfuelaround.Itproduces30%lesscarbondioxideperunitofheatthan
6、petroldoes,and45%lessthancoal.Conventionalcoal-firedpowerstationschurnout900kg(1,980pounds)ofthegasforeverymegawatt-hourofelectricitytheygenerate.Natural-gasplantsemitlittlemorethanhalfthatamount.Givensuchremarkablycheapnaturalgas,theoutlookforcoalisdire.Onaverage,coal-firedpowerstationsst
7、illproducethecheapestelectricity.Andbetweenthem,theystillaccountfor37%oftheelectricitygeneratedinAmerica(comparedwith30%fromnaturalgas,19%fromuranium,7%fromhydro,5%fromrenewablesand1%fromoil).Butcoal-firedstations,withtheirbelchingsmokestacks,arenotoriouspolluters,andfacetoughnewair-qualit
8、ystandardsthatwillrendermanyolderonesuneconomic.Atpresent,natural-gasplantshaveloweroperatingcoststhanonly9%ofcoal-firedstations.ButthetougheremissionstandardsproposedbytheEnvironmentalProtectionAgency(EPA)willmakenatural-gasplantsaseconomicallyattractiveas65%
