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II.CarbonSequestrationandManagementLecture7:Overview–TerrestrialEcosystemsLecture8:CarbonSequestrationinForestryLecture9:CarbonSequestrationinAgricultureTheProblemTheChallengeTheobjectiveofArticle2oftheUnitedNationsFrameworkConventiononClimateChange(UnitedNations,1992)is

“toachievestabilisationofgreenhousegasconcentrationsintheatmosphereatalevelthatwouldpreventdangerousanthropogenicinterferencewiththeclimatesystem.”WRE550Projectionsofclimatemodels

IS92a:businessasusualWRE550:ascenarioofCO2(550ppm)(Source:Wigley,Richels,andEdmonds,1996.Nature:397:240-243)Carbonmanagementisthecontrolofcarbonemissionswithintheeconomic,social,technicalandpolicyconstraintsthroughthereductionsofcarbonsourcesandtheenhancementsofcarbonsinks.

•NosingletechnologyorpolicyinstrumentcanprovideacompletesolutiontotheproblemofrisingatmosphericCO2concentrations.Anarrayofnewtechnologiesandresourceusepracticesmustbedeployed.

WhatistheCarbonManagement?•

Itfocusesondevelopingbreak-throughtechnologiesforthelargescalereduction(e.g.alternative,lowcarbon,energysources),removal(e.g.gasseparationfromflueemissions)andsequestration(e.g.longtermstorageingeological,terrestrial,andoceansystems)ofCO2.(Source:/carbon.htm#top)TheGoalsofCarbonManagementToincreasetheefficiencyofprimaryenergyconversionandendusesothatfewerunitsofprimaryfossilenergyarerequiredtoprovidethesameenergyserviceTosubstitutelower-carbonorcarbon-freeenergysources(e.g.renewableenergy,nuclearpower)forourcurrentsourcesToremoveCO2fromtheatmosphereandlockitawayandstoreintheterrestrialecosystemsoroceans(called“carbonsequestration”)RawindustrialemissionsentersmokestackCO2-richeffluentgasstreamentersatmosphereNaturalCO2separationandcaptureprocess(photosynthesis)LongTermSoilCarbonStorage1tonCO2=1CERCNoindustrialCO2separationprocessEnhancedEcologicalCarbonStorageCO2storage-enhancementpracticesadoptedsince1990areeligibleforCERCgenerationIndustrypaysthirdpartytostoreemittedCO2Separationprocess(removalofCO2)$$Rawindustrialemissionsentersmokestack“Scrubbed”effluentgasstreamentersatmosphereIndustrialCO2

captureprocess$$LongTermIndustrialCarbonStorage1tonCO2=1CERCIndustrialCarbonStorageIndustrymakesinternalinvestmentstolimitCO2emissions($$)SeparationandCaptureofCO2fromtheEnergySystemLecture7:CarbonSequestrationinTerrestrialEcosystems

1.Whatisthecarbonsequestration?CarbonsequestrationcanbedefinedasthenetremovalofCO2

fromtheatmosphereintolong-livedpoolsofcarbon.Itisimportanttoemphasizethatincreasingphotosyntheticcarbonfixationaloneisnotenough.Thiscarbonmustbefixedintolong-livedpools.Otherwise,onemaybesimplyalteringthesizeoffluxesinthecarboncycle,notincreasingcarbonsequestration.2.WhyisCarbonSequestrationImportant?Carbonsequestration(CS),representingoneofthreekeyapproachestocarbonmanagement,whichhasreceivedmuchlessattentiontodate

Severalreasons:•

CScouldbeamajortoolforreducingcarbonemissionsfromfossilfuels.(GiventhemagnitudeofcarbonemissionreductionsneededtostabilizetheatmosphericCO2concentration,multipleapproachestocarbonmanagementwillbeneeded)•

CSiscompatiblewiththecontinuedlarge-scaleuseoffossilfuels,aswellasgreatlyreducedemissionsofCO2totheatmosphere•

CScouldofferotherbenefitssuchas:improveagriculturalpracticesthatcouldreducesoilerosionincreasethesustainabilityoffoodproduction,conservewater,andbiodiversitythedevelopmentofexportabletechnologiestohelptheeconomy3.MainCharacteristicsforCarbonSequestrationSystemsAnyviablesystemforsequesteringcarbonmusthavethefollowingcharacteristics:•Capacityandprice

Thetechnologiesandpracticestosequestercarbonshouldbeeffectiveandcost-competitive.•Environmentallybenignfate-needtolookatenvironmentalsideeffects(e.g.,thelong-termeffectsofsequestrationonthesoilorvegetationoroceans)•StabilityThecarbonshouldresideinstorageforarelativelylongduration4.CarbonSequestrationinTerrestrialEcosystems

1).PotentialforCSinTerrestrialEcosystem•Totalamountofcarbonstoredinterrestrialecosystemislarge(2000±500PgC).•CSinterrestrialecosystemswillbeenhancedbyincreasingtheamountsofcarbonstoredinlivingbiomass,roots,soilcarbonandinlong-livedmaterialsthatcontainwoodymatter.•Computermodelsestimatethatterrestrialecosystems

(e.g.forests,vegetation,soil,farmcrops,pastures,tundra,andwetlands)–haveanetcarbonaccumulationofabout25-30%(1.5to2.0PgC)ofthe6-7PgCemittedannuallyintotheatmospherebyfossilfuelcombustionandlandusechanges2).Globalpotentialcarbonsequestrationrates(CSR)wereestimatedthatmightbesustainedoveraperiodof25to50yearsBiomesPotentialCSR(PgC/year)Agriculturallands(soilonly) 0.85-0.9Grasslands 0.5Rangelands 1.2Forests 1-3Desertsanddegradedlands 0.8-1.3Terrestrialsediments 0.7-1.7Borealpeatlandsandotherwetlands 0.1-0.7Total 5.7-10.1(Source:USDOEReport,1999)3).QuantifyingthePotentialCarbonSequestrationAssumingthatCSsystemshasthreeobjectives:increasethecarboninabove-groundbiomassincreasetheamountofcarboninbelow-aroundsystems(soilandsediment)managelandareawithanemphasistowardcarbonsequestrationThepotentialcarbonsequestration(PCS)isestimatedas:

PCS=[(aiAGCi+biBGCi)

ci

LAi]Where

ai=potentialincreaseinabove-groundcarbonintheithecosystembi=potentialincreaseinbelow-groundcarbonintheithecosystemci=potentialchangeinlandareaduetomanagementforcarbonsequestrationintheithecosystemAGCiandBGCiareabove-groundcarbonandbelow-groundcarbon(rootbiomass+soilcarbon)intheithecosystemLA=landareaofeachecosystemintheindexyear

4.

PotentialCarbonSequestrationAnalysis

Fourwaystoincreaseabove-groundcarbonsequestrationsystem:

•Increasetherateofaccumulationofabove-groundbiomass(PgC/yr)•Increasethedensityoftotalbiomassperareaandor/densityofcarbonintheabove-groundbiomass(PgC/area)•Increasebeneficialuseofbiomasscarboninlong-livedproducts

Fourwaystoincreasebelow-groundcarbonsequestrationsystem:

•Increasethedepthofsoilcarbon•Increasethedensityofcarbon(organicandinorganic)