Assessment of sustainable biomass resource for energy use in China

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AssessmentofsustainablebiomassresourceforenergyuseinChina

XinpingZhoua,b,*,FangWanga,HongweiHuc,LieYangc,PenghengGuod,BoXiaocDepartmentofMechanics,SchoolofCivilEngineeringandMechanics,HuazhongUniversityofScienceandTechnology,LuoyuRoad1037,Wuhan,Hubei430074,PRChinabHubeiKeyLaboratoryforEngineeringStructuralAnalysisandSafetyAssessment,LuoyuRoad1037,Wuhan430074,ChinacSchoolofEnvironmentalScienceandEngineering,HuazhongUniversityofScienceandTechnology,LuoyuRoad1037,Wuhan,Hubei430074,PRChinadKunmingInstituteofEnvironmentalScience,Kunming,Yunnan650032,PRChina

aarticleinfo

Articlehistory:

Received13March2010Receivedinrevisedform6July2010

Accepted2August2010

Availableonline17September2010Keywords:

SustainablebiomassresourceAgriculturalresiduesForestresiduesMunicipalsolidwasteGreenhousegases

abstract

ThispaperassessesthesustainablebiomassresourceforenergyinChina.Assessmenthasbeencarriedoutforthefollowingresources:(i)agriculturalresidues,(ii)forestresidues,and(iii)municipalsolidwaste(MSW).Thepotentialofeachresourceisestimatedforthebaseyears2008,2008,and2007.Theenergypotentialsoftheseresourcesin2008,2008,and2007areestimatedtobe14.7,3.9,and0.2EJ,respectively.Thetotalpotentialincludingtheenergyof6.4EJfromtheproposedlow-inputhigh-diversity(LIHD)grasslandbiomassontheuntilledlandsforthebaseyears1996isequaltoabout30.2%ofChina’senergyconsumptionin2008.Furthermoreitisprojectedthatsustainablebiomassuseforenergywillreducenetemissionsofgreenhousegases(GHG)of3276.7milliontonnes,andhelpinemission-reductiontargetofChinaandtheworld.

ª2010ElsevierLtd.Allrightsreserved.

1.Introduction

ThecurrentrapiddevelopmentofglobaleconomyandincreaseinpopulationandlivingstandardshavebeenposinggreatpressureonenergyresourcesandtheenvironmentespeciallyinChina.TherecentrapidincreaseinChina’senergyconsumptionisdemonstratedinFig.1[1].Chinahasbeentheworld’stopcarbonemittersecondtotheUnitedStatesofAmerica.InDecember2009,China’sStateCouncilannouncedthatthecountrywillcutitscarbonemissionsby

40e45%from2005levelsby2020.ThiswouldhavesignificantimplicationsforChinaandtherestoftheworld[2].ThereisanurgencytoutilizelocalrenewableenergysourceseffectivelytosupportandpromotelocaldevelopmentinChina.Thiswillalsoreducecarbonemission.BiomassisanabundantandrenewableenergysourcewithlownetCO2emission.Biomasscontainslesssulfurandashbutmorehydrogenthancoal.Itsgaseousorliquidproductionisclean.BiofuelfrombiomassbecomesasinkforGHGbecausebiomassislowincarbonandcarbonisfixedduringthebiomassgrowth.ALIHDgrassland

*Correspondingauthor.DepartmentofMechanics,SchoolofCivilEngineeringandMechanics,HuazhongUniversityofScienceandTechnology,LuoyuRoad1037,Wuhan,Hubei430074,PRChina.Tel.:þ8627873838.

E-mailaddress:xpzhou08@mail.hust.edu.cn(X.Zhou).

0961-9534/$eseefrontmatterª2010ElsevierLtd.Allrightsreserved.doi:10.1016/j.biombioe.2010.08.006

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biomassandbioenergy35(2011)1e11

Fig.1eChina’senergyconsumptionduring1978e2008[1].

Table1eThebiomassresourcecategoriesdistinguishedtoassessthetheoreticallyavailablepotentialofbiomassforenergyuse[23,24].CategoryAgriculturalresiduesForestresiduesDescriptionTheresiduesreleasedtogetherwithfoodproductionandprocessingTheresiduesreleasedtogetherwithwoodproductionandprocessingThebiomassthatcanbeproducedondeforestedoragriculturallydegradedormarginallandthatisstillsuitableforgrassland,orreforestationuseBiomassreleasedafterhuman’smaterialuse,e.g.MSW,sludgefromsewagedisposalplant,wastewood,etc.Biomassfromanimalmanureordirectlyonusedasafeedstockformaterialend-useoptionslikepulpandpaper,orforpetrochemicalindustry,orsmall-quantitybiomassenergycrops,etc.BiomassproductiononsurplusdegradedlandOrganicwastesOthers,e.g.,animalmanure,bio-materials,small-quantitybiomassenergycropsbiomasscanevenproducecarbon-negativebiofuelssincethebiomassisabsorberofmoreatmosphericCO2thanGHGreleasedinbiofuelproductionandcombustionandresultsinsignificantreductionofatmosphericCO2[3].Biomassthere-foreislikelytobeanattractiveoptionforreducingGHGemissionbesidesbeinganalternativeenergyresource.Recently,biomassenergyconversiontechnologiesespeciallypyrolysisandgasificationhavebecomehotstudyareas[4-15].

Thesustainablebiomassresourceavailableforenergyusecanbedividedintofivecategories:agriculturalresidues,forestresidues,biomassproductiononsurplusdegradedland,organicwastes,andothers(seeTable1).Biomassproductiononsurplusdegradedlandisthebiomassthatcanbeproducedondeforestedoragriculturallydegradedormarginallandthatisstillsuitableforgrassland,orreforestationuse.Organicwastesarethebiomassreleasedafterhumanmaterialuse.TheseincludeMSW,sludgefromsewagedisposalplants,wastewoodandsoon.ThedominantproductisMSW,whichconsistsofcombustibleandincombustiblecomponents.MSWusuallycanbeharmlesslydisposedinthreemainmethods:landfill,compost,andincineration.Thecombustibleorganiccomponentssuchaswasterubbertyre,wasteplasticandwastepaper,canbedirectlycombustedinMSWincineratorsorblendedwithotherfuelsuchascoal.TheMSWincinerationdisposalprocessisbeingusedmoreandmoreinChina,becausethisprocesscanrecycletheenergyfromMSWbesidesreducinglargelandusedforthelandfilldisposalprocess.Thepartofenergycontainedinlandfillgascanalsobeobtainedbycollectingthemtocombustatsite.Otherbiomassresourcesincludebiomassfromanimalmanureordirectlyonusedasafeedstockformaterialend-useoptionslikepulpandpaper,orforpetrochemicalindustry,orsmall-quantitybiomassenergycrops,e.g.,shortrotationcrops,fast-growingenergytrees,andsomekindsofgrassspecies,etc.

Someworkwasperformedonthepotentialofbiomassbasedononeortwokindsofbiomassbasedonolderstatisticaldata.

Table2eYieldsofmainagriculturalproductsduring1991to2008(Unit:104tonnes).YearGrainRiceWheatCornOtherBeansTubersSugarcaneOilCottonHempgrainscropsTotalPercentofgrainbiomasstototalagriculturalbiomass/%75.274.774.674.274.375.273.973.173.971.770.468.467.568.970.371.670.469.319911992199319941995199619971998199920002001200220032004200520062007200839566.340169.0517.4393.141611.5127.144349.345624.745304.140522.4398.239798.737428.741157.242776.045099.245632.447847.418381.318622.217751.417593.318522.619510.320073.519871.319848.718790.817758.017453.916065.617908.818058.818171.818603.4191.69595.310158.710639.09929.710220.711056.912328.910972.611388.09963.69387.39029.088.195.29744.510846.610929.811246.49877.39538.310270.49927.511198.612747.110430.913295.412808.610600.011408.812130.811583.013028.713936.515160.315230.016591.41712.41850.41856.61938.61669.71812.81516.11485.41258.71168.01094.11185.11131.31024.61036.1920.5869.1820.01247.11252.01950.42095.61787.51790.31875.52000.614.02010.02052.82241.22127.52232.12157.72003.71720.12043.32715.92844.23181.13025.43262.63536.03192.33604.230.63685.23563.13665.93513.33557.73468.52701.32807.82980.267.87301.119.46092.761.76818.778.78343.87470.36828.07566.39010.79023.584.98663.709.211295.112415.21638.311.21803.919.62250.32210.62157.42313.92601.229.828.927.22811.03065.93077.120.32568.72952.8567.50.8373.9434.1476.8420.3460.3450.1382.9441.7532.4491.86.0632.4571.4753.3762.4749.288.493.6.074.7.779.574.949.7.252.968.196.485.3107.4110.5.172.862.552613.453752.7342.253101.256020.259982.559999.362386.861340.1595.056295.758201.6575.359737.560825.062996.1859.369050.7biomassandbioenergy35(2011)1e11

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Table3eYieldsofmainagriculturalproductsinregionsofChinain2008(Unit:104tonnes).RegionTotalareaGrain/millionha151.91.61.218.815.7114.579.214.819.145.380.90.810.710.514.012.416.715.7101.616.618.621.218.023.83.5232.88.248.417.638.3120.2304.420.0.471.85.2166.55755.7121.5147.32758.5948.31780.0RiceWheatCornOtherBeansTubersCottonOilSugarcaneHempTotalgrainscrops137.00.310.555.60.170.51714.132.752.51221.9253.01.096.24.91.8.243.118.2998.221.21167.91.51.92034.23384.13051.0329.23.20.20.5636.658.2426.842.883.125.81172.2391.5268.142.0.1406.53707.988.084.31442.2682.81410.75094.011.02083.01822.02410.42.1203.011.1286.613.66.61887.42247.01615.0226.4128.063.5207.27.01806.0246.0637.0391.2529.62.21326.0483.6265.41.8149.9425.3196.60.50.138.912.4144.8173.760.1.272.0111.14.274.113.38.81.51.77.1.217.111.96.13.92.00.2138.15.5.211.93.163.4159.420.9.810.92.525.4239.62.11.345.934.8155.7826.552.9106.6667.0334.61.686.630.6130.017.326.741.9219.296.245.035.218.023.01.8305.037.8116.336.2112.12.7118.450.036.810.94.116.7344.21.90.3101.444.9195.7132.447.528.456.75.30.341.739.046.6109.759.1179.0568.2143.081.0104.51.6.430.71069.5276.3408.1214.8169.80.5390.782.0214.636.242.315.693.10.18.373.710.70.30.80.20.5187.30.332.62.836.311.2104.1141.365.151.324.70.21.61.60.1291.92.20.5152.619.1117.5128.848.551.828.5880.43.6150.341.3228.025.491.2340.61052.6505.3285.7133.881.537.58.7390.435.7249.968.430.46.0208.9.553.535.213.656.80.02.26726.7127.8157.73132.21057.82251.39071.61909.022.269.915293.0120.63367.4905.23320.0748.62126.04705.224491.95961.02595.53051.12523.999.2711.19565.71201.83514.61298.43450.0101.13901.51170.99.8137.0342.81296.0NorthofChinaBeijingTianjinHebeiShanxiInnerMongoliaNortheastofChinaLiaoningJilinHeilongjiangEastofChinaShanghaiJiangsuZhejiangAnhuiFujianJiangxiShandongCentralsouthofChinaHenanHubeiHunanGuangdongGuangxiHainanSouthwestofChinaChongqingSichuanGuizhouYunnanNorthwestofChinaShanxiGansuQinghaiNingxiaSinkiang0.12.20.016.70.216.5259.51.08.885.529.270.9.210057.520.726.577.01198.88215.6518.82098.011.2116.371.818.70.30.34.80.30.13.21.321.14.44.810.60.11.10.110.91.76.80.12.36.60.10.57966.52602.61760.0505.62705.0579.03501.51518.013151.0113.83047.2706.02846.7525.41872.34039.612432.05126.32101.22665.31070.91317.3151.06386.5.31771.9660.41383.5508.81862.1110.46759.43.11533.72528.01003.31107.6143.85690.33109.6839.1529.42615.61497.6907.0461.11236.7621.091.90.52851.9979.0637.1.7282.98.2194.383.13.866.441.0325.010.112.3302.66.1Zengetal.[16]estimatedthedistributionandquantityofcropstrawinChinain2002.WangandFeng[17]discussedthesupplyofbiomassenergyresourcesmainlybeingcrop-strawintheruralareaandtheeffectofthedischargeofnoxiousgasesfromuseofbiofuels.Liuetal.[18]studiedthedistribution,utilizationstructureandpotentialofcropresiduebiomassresourcesinruralChinabasedonthedatafrom1995to2005.Bydevelopingasystemaccountofbiomassresource,Jiangetal.[19]calculatedtheaggregatefluxesandindicatorsforagricul-turalbiomassresourceexploitationinChinain2004.LiandHu[20]estimatedthepotentialofusingafforestationforsustain-ablebiomassproductionforenergyinChina,basedonthe1998yeardataaboutthelandareaavailableforforestdevelopmentinthiscountry.ZhaoandZhou[21]estimatedthebiomassandnet

Table4eEstimatedagriculturalbiomassproduct-residuecoefficients[23,25].RiceWheatCornOthergrainsResiduesStrawStrawCoefficient0.6231.366StalksStalks21.366aBeansStemsandleaves1.5TubersSugarcane0.5Leaves0.1OilcropsCottonHempStemsandleaves2.5StemsandleavesStalks23aAnintermediatevalueamongthecoefficientsofthreemaingrainsisusedat1.366foragriculturalbiomassproduct-residuecoefficientsofothergrains.4

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Table5eYieldsofagriculturalbiomassresiduesduring1991to2008(Unit:104tonnes).Year199119921993199419951996199719981999200020012002200320042005200620072008Rice11451.511601.611059.110960.611539.6121.912505.812379.812365.811706.611063.310873.710008.811157.211250.711321.1115.911955.1Wheat13107.213876.814532.9135.013961.515103.716841.314988.615556.013610.312823.112333.611814.312560.613311.014816.414930.115362.6Corn197.619076.6200.819855.022397.2294.220861.726590.825617.321200.022817.524261.523166.026057.427873.130320.630460.133182.8Othergrains1703.51710.226.22862.62441.72445.52561.92732.82587.12745.72804.13061.52906.23049.02947.42737.12349.72791.1Beans1870.71878.02925.63143.42681.32685.52813.33000.92840.93015.03079.23361.83191.33348.13236.53005.62580.230.9Tubers1358.01422.11590.61512.71631.31768.01596.11802.11820.31842.61781.51832.91756.61778.81734.31350.61403.91490.1Sugarcane679.0730.11.9609.36.2681.97.0834.4747.0682.8756.6901.1902.38.5866.4970.91129.51241.5Oilcrops3276.63282.33607.93979.24500.74421.24314.84627.75202.35909.75729.85794.45622.06131.861.35280.65137.55905.6Cotton1702.51352.51121.81302.31430.31261.01380.81350.31148.71325.21597.11474.91457.917.11714.32259.82287.12247.6Hemp757.8874.7862.9559.5578.5808.51062.8591.0617.3638.1587.4611.65.4601.5670.8613.9598.9709.6Total55124.7551.8524.857975.961461.966214.663851.868431.268003.362170.262622.5136.461038.767146.9693.072285.572050.077397.6primaryproductivityofmajorplantedforestsinChinabasedonthefourthforestinventorydata(19e1993).Tangetal.[22]estimatedsome45millionhm2ofmarginallandtobebroughtintohighpotentialbiomassenergyproduction,andcarriedoutacasestudyonmarginallandinNingnanCounty,SichuanProvincewithpercapitacroplandof0.07ha.Thecasestudyindicatedthatdrybiomassofsome0.38milliontonnescouldbeproducedeachyearfromannualpruningofmulberrytrees.Liaoetal.[23]estimatedthequantityofagriculturalandforestresiduebiomassresourceinChinabasedonthe1999yeardatawhileZhouetal.[3]estimatedthepotentialofusingenergyfromlow-inputhigh-diversity(LIHD)grasslandbiomassondegradedlandsinChina.

Withtheseworksinmind,weassessinthispaperthedistributionandquantityofsustainablebiomassresourcesinChinaincludingthemainbiomassresidueswhichare:(i)agriculturalresidues,(ii)forestresidues,and(iii)MSWbasedontheavailablelatestdata.WealsoestimatethebiomassenergypotentialincludingenergyfromtheproposedLIHDgrasslandbiomassontheuntilledlandsforthebaseyear1996levelanditsdistributioninregionsofChina,byconsideringtheunuseddegradedlandswhichcanbeusedforLIHDgrasslandbiomass.

2.

2.1.

Biomassresource

Agriculturalresidues

Residuesofagriculturalcropsarethepotentialbiomassresourceforenergy.Weestimatetheagriculturalbiomassresidues(drybasis)basedonyieldofmainagriculturalprod-uctsmultipliedbytheestimatedagriculturalbiomasspro-ducteresiduecoefficients.Theyieldsofmainagriculturalproductsduring1991e2008arepresentedinTable2[1].Inthepresentwork,grainsaretakentoincluderice,wheat,corn,andothergrains(e.g.,grainsorghum),whileoilcropsincluderape,sunflower,peanut,sesamecrops,andothers.Thetotalagriculturalyieldincreasedalittlefrom52613.4Â104tonnes

in1991to69050.7Â104tonnesin2008.Theyearlyaverageincreaseisfoundtobe966.9Â104tonnes,whichisequalto1.4%ofthevaluein2008.Grainyieldsdominatetheyieldsofthemainagriculturalproductswithyearlyaveragepercentofgrainyieldtothetotalbeing72.1%.

Table3presentsyieldofmainagriculturalproductsinalltheregionsofChinain2008[1].ThemostagriculturalproductyieldsareinCentralsouthandEastofChina,accountingfor35.5%,and22.1%,respectivelyofthenationalyield.SouthwestofChina,Northeast,NorthofChina,cover13.9%,13.1%,and9.7%,respectively.Theleastyieldreaching5.7%isobtainedinNorthwestofChinawherethepopulationissparseandmostoflandsareagriculturallydegraded,thoughthisregionhasanareaof304.4millionha,accountingfor32%ofthenationalland.SugarcanefocusisinCentralsouthandSouthwestofChina,andalittleintheEastofChinabecauseofrainyweatherintheseregions.CottonyieldsinNorthwest,East,andCentralsouthofChinareached87.2%ofthenationalyieldat749.2Â104tonneswithavalue43.4%inNorthwestofChina.TheCentralsouthandEastofChinainthisregardisconsideredtobetheagriculturalbaseofChina.

Theyieldsofagriculturalresiduebiomassduring1991e2008andthoseinregionsofChinain2008areestimatedwiththeagriculturalbiomassproduct-residuecoefficients[25](Table4)andpresentedinTables5and6.Withanincreaseintimefrom1991to2008,thetotalagriculturalresidueincreasedslowlyfrom55124.7Â104tonnesin1991to72050.0Â104tonnesin2007,andsuddenlyroseto77397.6Â104tonnesin2008.Ontheotherhand,theagriculturalbiomassresiduesinEast,Centralsouth,Northeast,NorthandSouthwestofChinareached18153.2Â104tonnes,17828.0Â104tonnes,14677.3Â104tonnes,11570.3Â104tonnes,and8850.6Â104tonnes,respectively.TheamountofagriculturalresiduesinNorthwestofChinareaching6317.7Â104tonnesranksleastduetofewagriculturalcropsintheregion.TheagriculturalresiduesinNortheastofChinaisclosetothetwohighestvaluesinEastandCentralsouthofChina,resultingfromtheconcentrationofabout1/3ofnationalcorncropsinNortheastofChinaandahighvalueofagriculturalbiomassproduct-residuecoefficientof2forcorn.

biomassandbioenergy35(2011)1e11

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Table6eQuantityofagriculturalresiduesin2008(Unit:104tonnes).RegionNorthofChinaBeijingTianjinHebeiShanxiInnerMongoliaNortheastofChinaLiaoningJilinHeilongjiangEastofChinaShanghaiJiangsuZhejiangAnhuiFujianJiangxiShandongCentralsouthofChinaHenanHubeiHunanGuangdongGuangxiHainanSouthwestofChinaChongqingSichuanGuizhouYunnanNorthwestofChinaShanxiGansuQinghaiNingxiaSinkiangRice85.40.26.534.60.143.91621.4315.0360.7945.73978.855.61103.9411.4861.9317.01160.168.84211.2276.1955.51574.9625.1690.0.61937.3329.33.0287.3386.90.3121.051.82.40.041.425.5Wheat2341.4.771.71669.2345.6210.4131.46.72.4122.35796.024.91363.629.01595.42.02.62778.74622.74167.7449.74.40.30.70.0869.679.5583.058.5113.435.21601.3534.8366.257.487.5555.3Corn7415.9175.9168.62884.31365.62821.410188.02378.04166.034.04820.84.2405.922.2573.227.313.23774.84494.13230.0452.8256.0126.9414.413.93612.0492.11274.0782.41059.14.52652.0967.2530.83.6299.9850.6OthergrainsBeansTubersSugarcaneOilcropsCottonHemp327.32.81.762.747.5212.61128.972.2145.6911.1457.12.2118.341.7177.523.636.557.2299.4131.461.448.124.631.42.16.751.6158.949.4153.23.6161.768.250.214.95.622.8359.43.11.968.852.1233.51239.779.3159.91000.5501.92.4129.945.8194.925.940.162.9328.8144.367.552.827.034.52.7457.556.7174.5.3168.24.0177.674.955.116.36.225.0172.10.90.250.722.597.866.223.714.228.3237.60.120.819.523.3.829.6.5284.171.0.552.377.327.215.4534.8138.2204.1107.484.90.3195.441.0107.318.121.17.80.00.00.00.00.00.00.00.00.00.025.90.10.98.52.97.16.40.01005.72.12.67.7119.9821.651.9209.81.111.67.21.90.00.00.00.00.00.00.0583.84.31.0305.238.2235.1257.697.0103.757.01760.87.2300.682.56.150.8182.4681.32105.31010.7571.5267.6163.175.117.4780.871.4499.9136.860.812.1417.398.9107.170.427.1113.7279.40.424.9221.232.00.92.30.71.60.0562.01.097.88.5109.00.033.6312.2423.9195.31.074.00.00.60.04.90.04.70.30.00.0974.930.237.00.00.0907.77.20.00.01.52.13.3.98.116.319.578.90.00.10.96.334.811.924.71.266.829.8.312.37.20.0393.821.457.199.5215.90.021.618.12.60.20.50.1Total11570.3232.4276.45296.91903.63861.014677.32972.9.86749.918153.297.732.3669.002.2508.51507.67825.417828.09239.92767.523.311.32098.4193.68850.61224.53860.51483.72222.059.96317.71867.31257.3180.7488.82523.62.2.Forestresidues

Since1973,ChinahasperformedsevenNationalForestrySurveyswithaperiodoffiveyearsexceptafour-yearperiodatthefirstNationalForestrySurvey(Table7)[26e29].OnNovember17,2009,InformationOfficeoftheStateCouncil

announcedthedataoftheseventhNationalForestrySurveyduring2004e2008.Theforestareareached19500Â104hawithcoverrateof20.36%,whichincreasedby20.3Â104hafromthevalueof17490.92Â104haatthesixthSurveyduring1999-2003.Thetotalcarbonstorageforforestreached78.1Â108tonnes.Chinarealizedthatforestcoverrategoalof

Table7eSevenNationalForestrySurveydata[26e29].NumberofNationalForestrySurvey1st2nd3th4th5th6th7thDate1973e19761977e19811984e198819e19931994e19981999e20032004e2008Forestarea/104ha1218611527.7412465.2813370.351.117490.9219500Forestcoverrate/%12.71212.9813.9216.5518.2120.36Increment/104haeÀ658.26937.905.072523.751596.8320.36

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Table8eForestresiduesestimatedbasedondataofforestareafromseventhNationalForestrySurvey.TimberstandsForestarea[27,28]PercentofforestareatothetotalDryproductyieldsperhectare/tones[23,25]Product-residuecoefficient[23,25]Residues/tones1632.9%3.750.512030Protectionforests820842.1%3.750.26156Firewoodforests1750.9%3.751.0656.3Special-useforests11986.1%1.8750.1224.6Economicforests204110.5%1.8750.1382.7Others14627.5%1.8750.1274.1Total19500100%19723.7morethan20%fromtheyear2005leveltwoyearsaheadofscheduledtime(theyear2010)andismakinggreatereffortstoachievetheyear2020goalofincreasingforestareaby4000Â104hafromtheyear2005level.Theincreaseinforestareaisdrivenbystronggovernmentsupport.Thegovernmentpumped2538Â108Yuanintoforestreconstructionduringtheperiod2004e2008[30].Forestresourcesmainlyincludetimberstands,protectionforests,firewoodforests,forestsforspecialuses,andotherforestssuchaseconomicforests.

BasedonthedataofforestareafromtheseventhNationalForestrySurvey[27,28],thequantitiesofbiomassresiduebiomassofthesixforestsareestimatedaccordingtoforestproductyields(drybasis)perhectareandtheestimatedforestbiomassproduct-residuecoefficients[23,25]andpresentedinTable8.Productyields(drybasis)perhectareforforestinChinaarelessthanthevaluesinaEuropeanclimate[31].Thetotalforestresiduebiomasscanbeestimatedtobe197.2milliontonnes.

2.3.MSWorganics

Table9presentsthedisposedquantityandtheharmlessdisposedquantityofMSWorganicsduring1999e2007[32].QuantityofharmlessdisposalMSWbasicallyincreasedwithtime,by2201.3Â104tonnesfrom7232Â104tonnesin1999to9433.3Â104tonnesin2007,however,harmlessdisposalratedecreasedfrom63.4%in1999to52.1%in2004,andthensuddenlyincreasedfrom52.2%2006to62.03%in2007.ThismeansthatharmlessdisposalfacilitycouldnotsatisfytheincreaseinMSWvolumeduring2000e2006.Table10presentsthedistributionandharmlessdisposalquantityofMSWanditsenergypotentialinregionsofChinain2007.Theharmlessdisposalratesareabove79%inthemostdevelopedregionsofChina,e.g.,Beijing,Tianjin,Shanghai,Jiangsu,Zhejiang,Fujian,Shandong,Chongqing,Yunnan,andthehighestvalueof95.7%isattainedinBeijing.TheMSWquantitydisposedwithsanitarylandfillmethodaccountsfor80.9%ofalltheharmlessdisposalMSWinChina.Compost,incineration,and

otherdisposalmethodsaccountfor2.65%,15.2%,and1.25%,respectively.OriginaltargetofChinesegovernmentwasannouncedthatby2010,sanitarylandfillshouldaccountfor70%,compostfor20%,andincinerationfor10%,respectively[33].TheMSWquantitydisposedbyincinerationisabout0.5timeslargerthanthecorrespondingoriginaltargetvalue.OnetonneMSWdisposedwithsanitarylandfillcanproducelandfillgasesof130.8m3,whichcontainsmethaneof0.0467tonneestimatedaccordingtomethane’svolumecontentof50%recommendedbyIPCC2006[34].Landfillgases(1m3)areestimatedtogenerateelectricityof1.53kWhwhenitisassumedthatlandfillgaspowergeneratingefficiencyisequalto31%[34].Incinerationof1tonneMSWcangenerateelectricityof200–300kWhbydeductingthepowerutilizationoftheIncinerationplant.Thelowervalueof200kWhisusedinthispaper[35].

AsshowninTable10,theenergycanbeobtainedfromtheMSWincinerationandlandfillgascombustion.Thepotentialelectricitysupplycanreach18862.6GWh.Thehighestvalueof70.1GWhhasbeenachievedinEastofChina,accountingfor37.5%ofthenationaltotalelectricpowerfromMSW,4715.3GWhinCentralsouthofChina,2655.3GWhinNorthofChina,1788.3inSouthwestofChina,1721.1GWhinNortheastofChina,and917.6GWhinNorthwestofChina.Thepotentialenergydistributionshowsthatthereisbasicproportionalitytotheeconomicdevelopmentlevelintheregionsstudied.MoreMSWisproducedandhigherharmlessdisposalrateisseenindevelopedanddenselypopulatedregions.Forexample,thepotentialelectricityinCentralsouthofChinais4715.3GWhlowerthanthatofEastofChinaat70.1GWh,thoughtheirMSWdisposalquantitiesarealmostequal.ThisresultsfromthelowerMSWdisposalrateof57.2%inCentralsouthofChinacomparedtoavalueof76.5%inEastofChina.

2.4.Grassbiomassondegradedlands

Comparedtoconventionalbiofuelsbeingnetcarbonsources,LIHDbiofuelbelongstocarbon-negativebiofuelwhich

Table9eQuantityofharmlesslydisposedMSWorganicsduring1999to2007.ItemVolumeofdisposal/104tonnesHarmlessdisposalrate/%Quantityofharmlesslydisposed/104tonnes199911415.263.4723220001181961.4725520011347058.27839.200213650.274042003eee20041550952.18080.120051557751.78053.30920061484152.27747.00220071521562.09433.3Table10eMSWquantityanditsenergypotentialinregionsofChina.RegionVolumeofQuantityofSanitaryCompost/104Incineration/104ProportionLandfillElectricityElectricityTotal/GWhMSWharmlesslandfill/104tonnestonnesofharmlesslygases/104m3fromfromdisposed/104disposaltonnesdisposedmethane/GWhincinerationtonnesMSW/104MSW/%/GWhtonnesTotal15214.59437.77632.7250.01435.162.01527486.515274.93587.818862.6NorthofChina2167.41423.91199.4107.5102.066.9240028.72400.3255.02655.3Beijing600.9575.3535.139.11.095.7107086.41070.92.51073.4Tianjin165.01.0113.240.793.3226.0226.5101.8328.3Hebei686.5366.4277.946.142.353.455614.5556.1105.8661.9Shanxi365.1139.3121.318.038.224275.0242.845.0287.8InnerMongolia349.9188.9151.922.3.030398.8304.00.0304.0NortheastofChina2302.8874.2821.321.931.039.21361.813.677.51721.1Liaoning771.4436.0399.521.914.656.579949.5799.536.5836.0Jilin568.2216.9200.516.438.240124.9401.241.0442.2Heilongjiang963.2221.3221.323.044287.4442.90.0442.9EastofChina4334.63445.921.761.8791.076.5508655.25086.61977.570.1Shanghai690.76.7377.358.7108.079.275506.8755.1270.01025.1Jiangsu8.4780.9577.8203.086.9115631.61156.3507.51663.8Zhejiang772.0674.4401.7266.187.4803.8803.9665.31469.1Anhui400.2196.4176.710.9.135361.9353.626.3379.9Fujian376.1307.0167.53.1136.381.633520.8335.2340.8676.0Jiangxi252.2177.8177.870.535582.0355.80.0355.8Shandong945.0762.7662.967.180.7132662.21326.6167.81494.4CentralsouthofChina40.92335.41802.345.4443.457.2360683.53606.81108.715.3Henan737.04.9337.835.630.8.967601.9676.077.0753.0Hubei673.2282.0269.041.953833.4538.30.0538.3Hunan511.2269.7269.752.853973.4539.70.0539.7Guangdong1833.81155.8735.63.663.0147211.21472.1974.02446.1Guangxi246.4168.5140.29.818.568.428057.4280.6.3326.8Hainan87.8.550.04.562.110006.2100.111.3111.3SouthwestofChina1211.4900.5811.413.365.874.1162380.61623.81.51788.3Chongqing200.5165.1111.0.182.322213.8222.1135.3357.4Sichuan8.5383.5361.811.769.972404.9724.029.3753.3Guizhou183.9130.9130.971.226196.2262.00.0262.0Yunnan256.6206.4193.113.380.4383.9386.40.0386.421.914.614.666.72921.829.20.029.2NorthwestofChina1108.4458.1456.50.01.650.1356.6913..0917.6Shanxi333.6174.9173.31.652.434681.5346.84.0350.8Gansu259.968.468.426.313688.5136.90.0136.9Qinghai.761.461.494.912287.6122.90.0122.9Ningxia110.057.657.652.411527.1115.30.0115.3Sinkiang340.295.5.828.219171.9191.70.0191.7biomassandbioenergy35(2011)1e117Table11eLandresourcesfromChina’sfirstwidespreadinvestigationoflandresourcesandpotentialLIHDgrasslandbiomassenergyin1996[3].RegionTotalWasteSalinaWetlandSandlandBarrenRockyRibbingOthersTotalPotentialPercentPotentialareagrasslandland/million/millionsoillandlandland/millionuntilledareaLIHDgrasslandofuntilledenergy/PJ/million/million/millionhaha/million/million/millionha/million/millionhaareatohahahahahahahathetotal/%Total950.6849.2510.174.350.493.93103.5312.4710.94245.0970.571006351.0NorthofChina151.866.040.481.357.420.266.751.011.1324.458.4610761.2Beijing1.0.130000.010.060.0100.220.140.112.3Tianjin1.190.040.01000000.010.070.0504.8Hebei18.842.510.130.010.030.020.930.280.134.052.701.7242.9Shanxi15.672.650.0600.010.060.840.0.815.062.912.1261.7InnerMongolia114.510.720.281.337.380.184.920.080.1815.062.666.1239.6NortheastofChina79.183.780.432.130.060.020.110.080.386.996.152.8553.8Liaoning14.811.120.020.020.010.010.070.080.181.511.190.6107.3Jinli19.110.440.390.140.040.010.010.010.091.130.940.484.6Heilongjiang45.262.220.021.970.0100.0300.114.3.021.8361.9EastofChina80.842.420.260.010.050.060.1.790.215.342.922.2263.0Shanghai0.820000000000.0000.1Jiangsu10.670.050.020000.020.030.020.150.080.16.9Zhejiang10.0.340.01000.010.070.240.030.70.380.334.2Anhui14.010.21000.0100.070.420.040.750.270.323.9Fujian12.410.0000.010.110.280.010.960.580.452.5Jiangxi16.690.67000.020.030.10.240.051.130.740.466.4Shandong15.710.590.2400.0100.170.580.061.650.880.779.1CentralsouthofChina101.595.920.010.020.060.23.472.420.3112.416.425.1578.0Henan16.550.880.010.010.040.070.440.240.191.871.000.0.0Hubei18.591.310000.050.240.5102.121.410.9127.3Hunan21.190.60000.050.40.930.052.040.750.867.9Guangdong17.980.57000.010.020.090.250.030.970.630.456.3Guangxi23.762.30000.012.30.490.045.162.372.1213.6Hainan3.0.2500000.01000.260.250.122.9SouthwestofChina232.7717.180.550.140.460.5322.885.736.86.3319.6122.217.9Chongqing8.230.340000.020.230.910.011.520.450.0.9Sichuan48.410.7300.080.230.052.51.980.25.771.082.497.4Guizhou17.620.550000.011.041.102.70.671.160.2Yunnan38.324.530000.220.851.660.037.34.933443.4120.2111.020.550.060.220.2318.270.086.6237.0512.4815.11123.1NorthwestofChina304.4213.928.440.62.452.8669.781.432.04141.5727.0057.72430.0Shanxi20.580.750.0300.130.030.10.1301.170.820.573.7Gansu40.411.780.410.041.820.3810.551.070.0716.112.756.6247.2Qinghai71.751.083.910.296.141.5710.520.121.2124.846.8110.1612.9Ningxia5.20.080.0700.1500.10.080.330.820.190.317.2Sinkiang166.4910.234.020.3234.210.8848.510.030.4298.6216.4340.21479.08biomassandbioenergy35(2011)1e11biomassandbioenergy35(2011)1e11

9

Table12ePotentialenergyfromsustainablebiomassresourcesandnetreductionofGHGemissionsperyear.AllthebiomassAgriculturalresiduesForestresiduesMSWorganicsLIHDgrasslandbiomassOtherenergyresources2008yearenergyresiduesPotentialenergy/EJ25.214.73.9Percentto2008year30.2%17.6%4.7%energyconsumptionNetreductionof3276.71449.4388.8GHGemissions/milliontonnesabsorbsmoreatmosphericCO2thanGHGreleasedinbiofuelproductionandcombustion,thusleadingtogreatreductioninatmosphericCO2[3,36].Zhouetal.proposedutilizationofcarbon-negativebiofuelsfromLIHDgrasslandbiomassondegradedlandsforenergyinChina.TheinvestigationshowsthattheenergyoutputofLIHDbiomassondegradedsoilisnearlyequaltothatofethanolfromconventionalcorngrainonfertilesoilbytakingintoconsiderationenergyequivalenttoGHGcaptureandstorage.TheLIHDbiofuelisfarmoreeconomicalthantheconventionalbiofuelssuchascornethanolorsoybeanbiodiesel[3,36].

Accordingtoallthewastegrasslandandthebarrensoilland,90%ofthewetlandandthesalineland,and10%ofribbinglandandotherlands,and4%ofsandlandbeingavailableforLIHDgrasslanddevelopment,thelandareaavailableforLIHDgrasslanddevelopmentcanbeestimatedtobe70.6millionhafromthebaseyear1996asshowninTable11,accountingfor29%oftotaluntilledland[3,37].

TheresultsshowthatthepotentialenergyproductionofLIHDbiomassondegradedsoilsreached6.35EJyearÀ1afigurebasedonbiomassproductivityof90GJhaÀ1yearÀ1byneglectingperformancedifferenceamongallthetypesofavailabledegradedlands[36].Thisvalueaccountsforabout7.6%ofChina’senergyconsumptionin2008.TheyearlypotentialenergyproductionsinNorthwest,andSouthwestofChinareach2.43and1.75EJ,respectively.Thesumofthesevaluesinthetworegionsaccountsfor65.8%ofthenationaltotal,wherethepopulationissparseandmostofthelandsof195.9millionha(i.e.79.9%ofnationaluntilledlandsof245.1millionha)areagriculturallydegraded.

2.5.Energypotential

Table12presentsalltheenergypotentialofthefourmainkindsofsustainablebiomassresourcesandcomparesthemtoChina’senergyconsumptionin2008.Lowererheatvalueofstandardcoalisusedfor29.27MJ/kg[1],whiletheheatvalueofagriculturalandforestbiomass(drybasis)uses19and20MJ/kg,respectively[6,38].Withimprovementofcoalcombustionsystemefficiency,thestandardcoalconsumptionofgenerating1kWhofelectricityinChinagraduallydecreased,forexamplefrom383gin2002[38]to345gduringJanuarytoNovember2008andto339gduringJanuarytoNovember2009[39].InthisworkofestimatingthepotentialenergyfromMSWorganics,theMSWorganicsareequivalenttostandardcoalsaccordingtopotentialelectricity.Inorderto

ondegradedconsumptionsoils0.26.458.283.40.2%7.6%69.8%18.41420[3]generatetheequalpotentialelectricityof18862.6GWhfromMSW,thestandardcoalswithenergyofabout0.2EJwouldbeneededin2009.Withimprovementofcoalcombustionsystemefficiency,thestandardcoalconsumptionofgenerating1kWhofelectricityinChinagraduallydecreased,forexamplefrom383gin2002[39]to345gduringJanuarytoNovember2008andto339gduringJanuarytoNovember2009[40].InthisworkofestimatingthepotentialenergyfromMSWorganics,theMSWorganicsareequivalenttostandardcoalsaccordingtopotentialelectricity.Inordertogeneratetheequalpotentialelectricityof18862.6GWhfromMSW,thestandardcoalswithenergyofabout0.2EJwouldbeneededin2009.

ThetotalenergypotentialofChinacanreach25.2EJyearÀ1,andaccountsforabout30.2%ofChina’senergyconsumptionat83.4EJin2008,wherethepotentialagriculturalresidueshaveashareof17.6%,LIHDgrasslandbiomassondegradedsoils7.6%,forestresidues4.7%,andMSWorganicsonlyaccountsfortheleastshareof0.2%(Fig.2).Otherenergyresourceswithenergyof58.2EJwillbeneededfromthebaseyear2008levelbyassumingallthepotentialsustainablebiomassresourcesareusedforenergy.Thetotalenergypotentialalsoreaches22.6%oftheChina’senergyconsump-tionwhenthepotentialLIHDgrasslandbiomassondegradedsoilsisnottakenintoconsideration.PotentialuseofthesustainableresiduebiomassforenergyavoidsnetGHGemissions,whichwillhelpinemission-reductiontargetofChinaandtheWorld.BiofuelfromLIHDgrasslandbiomassondegradedsoilsactingasacarbon-negativebiofuelwillreducethenetGHGemissionsby1.42billiontonnesperyear[3].Helleretal.analyzedthelifecycleenergyandenvironmentalbenefitsofgeneratingelectricityfromwillowbiomass.Theyfoundataco-firingrateof10%biomass,thesystemnetglobalwarmingpotentialdecreasesby7e10%,netSO2emissionsare

Fig.2eStructureofenergyincludingpotentialenergyfromsustainablebiomassresources(Unit:EJ).

10

biomassandbioenergy35(2011)1e11

Table13eChangeofenergyconsumptionstructurefromthebaseyear2008whenpotentialenergyfrombiomassresiduesisconsidered.CoalOilOriginalenergystructure68.7%18.7%Modifiedenergystructurewithpotential38.5%18.7%bioenergyreducedby9.5%andasignificantreductioninNOxemissionsisexpected[38].Inthiswork,avalueof8.5%isusedforthedecreaseratioofnetglobalwarmingpotentialfortheresiduesbiomassexceptLIHDgrasslandbiomassondegradedsoils.Relatedto1kWhofusableelectricityfromcoalcombustioninChinain2002,theemissionsofCO2,SO2,NOx,CO,CH4,andNMVOC,were877,8.04,5.23,1.25,2.65,and0.395g,respec-tively[39].Duetoreductionofcoalconsumptionofgenerating1kWhofelectricityfrom2002to2009,theemissionsofCO2,SO2,NOx,CO,CH4,andNMVOCin2009,wereestimatedtobe776.248,7.116,4.629,1.106,2.346,and0.350g,respectively.TheGHGemissionsmainlyincludingCO2,CH4,andN2Ocanbeestimatedwiththeglobalwarmingcoefficientsrespectivelybeingequalto1,21and310[41,42].Inthiswork,0.978kgCO2eq.isassumedtobereleasedwhen1kWhofelectricityisgeneratedfromcoalalone[37].ThetotalnetGHGemissionsof3276.7milliontonnesarereducedduetothepotentialresiduebiomassforalternativeenergyofcoal.Thefiguresinthetablecangivethepolicy-makerareferencetosupporttheresearchanddevelopmentofbiomasscollectionandbiomassenergyconversiontechnologies.

3.Conclusion

Chinaisthelargestdevelopingagriculturalcountry,whereagriculturalresiduesareavailableinlargequantities(774milliontonnes)withpotentialenergyproductionof14.7EJ.Theforestcoverrateincreasedto20.36%undersupportofthegovernmentattheendof2008,andthisproducesmoreresi-dueswhichcangenerateenergyof3.9EJ.TheMSWorganicscanalsoproduceenergyofabout0.2EJ.ThepotentialLIHDgrasslandbiomassondegradedsoilscanaswellproduceenergyof6.4EJ.Thetotalenergypotentialisabout25.2EJyearÀ1,whichaccountsforabout30.2%ofChina’senergyconsumptionat83.4EJin2008;22.6%ofpowercanbeobtainedevenifthepotentialLIHDgrassondegradedsoilsisnottakenintoconsideration.ThesefactorswillchangetheenergyconsumptionstructureofChina.Thesustainableresiduebiomasscanbeusedforenergybyreplacingapartofcoalconsumption(Table14).Thesustainableresiduebiomasstogetherwithotherrenewableenergyresources(e.g.,hydro-energy,solarenergy,windenergy,nuclearenergy)accountsforabout40%ofthenationalenergyconsumptionfromthebaseyear2008,whichwillpromotethesustainabledevelop-mentofthecountry(Table13).Furthermore,totalnetreduc-tionofGHGemissionsof3276.7milliontonnescanbereached.Thiswilldefinitelyslowdownglobalwarmingconsiderablyontheearth’ssurface.

NaturalgasSustainableOtherrenewablebiomassenergyresources3.8%e8.9%3.8%30.2%8.9%Acknowledgements

ThisresearchhasbeensupportedbytheNationalNaturalScienceFoundationofChina(No.50908094andNo.20876066).

references

[1]NationalBureauofStatisticsofChina.Statisticsyearbookof

Chinain2008.Beijing,China:ChinaStatisticsPress;2009.[2]QiuJ.China’sclimatetarget:isitachievable?Nature2009;

462:550e1.

[3]ZhouXP,XiaoB,OchiengRM,YangJK.Utilizationofcarbon-negativebiofuelsfromlow-inputhigh-diversitygrasslandbiomassforenergyinChina.RenewSustainEnergyRev2009;13:478e85.

[4]S¢rumL,Gr¢nliMG,HustadJE.Pyrolysischaracteristicsand

kineticsofmunicipalsolidwastes.Fuel2001;80:1217e27.[5]McKendryP.Energyproductionfrombiomass(part2):

conversiontechnologies.BioresourTechnol2002;83:47e.[6]McKendryP.Energyproductionfrombiomass(part3):

gasificationtechnologies.BioresourTechnol2002;83:55e63.[7]FaaijA.Modernbiomassconversiontechnologies.Mitigat

AdaptStratGlobalChange2006;11:335e67.[8]AhoA,KumarN,LashkulAV,Era¨nenAV,ZiolekM,DecykP,

etal.Catalyticupgradingofwoodybiomassderivedpyrolysisvapoursoverironmodifiedzeolitesinadual-fluidizedbedreactor.Fuel2010;:1992e2000.

[9]BarnetoAG,CarmonaJA,BlancoMJD.Effectoftheprevious

compostingonvolatilesproductionduringbiomasspyrolysis.JPhysChemA2010;114:3756e63.

[10]SunSZ,TianHM,ZhaoYJ,SunR,ZhouH.Experimentaland

numericalstudyofbiomassflashpyrolysisinanentrainedflowreactor.BioresourTechnol2010;101:3678e84.

[11]Gomez-BareaA,LecknerB.Modelingofbiomassgasification

influidizedbed.ProgEnergyCombustSci2010;36:444e509.[12]SeoMW,GooJH,KimSD,LeeSH,ChoiYC.Gasification

characteristicsofcoal/biomassblendinadualcirculatingfluidizedbedreactor.EnergyFuels2010;24:3108e18.

[13]ArenaU,ZaccarielloL,MastelloneML.Gasificationofnatural

andwastebiomassinapilotscalefluidizedbedreactor.CombustSciTechnol2010;182:625e39.

[14]GuoXJ,XiaoB,ZhangXL,LuoSY,HeMY.Experimentalstudy

onair-streamgasificationofbiomassmicronfuel(BMF)inacyclonegasifier.BioresourTechnol2009;100:1003e6.

[15]LuoSY,XiaoB,GuoXJ,HuZQ,LiuSM,HeMY.Hydrogen-rich

gasfromcatalyticsteamgasificationofbiomassinafixedbedreactor:influenceofparticlesizeongasificationperformance.IntJHydrogenEnergy2009;34:1260e4.[16]ZengXY,MaYT,MaLR.Utilizationofstrawinbiomass

energyinChina.RenewSustainEnergyRev2007;11:976e87.[17]WangXH,FengZM.Biofueluseanditsemissionofnoxious

gasesinruralChina.RenewSustainEnergyRev2004;8:183e92.

biomassandbioenergy35(2011)1e11

11

[18]LiuH,JiangGM,ZhuangHY,WangKJ.Distribution,

utilizationstructureandpotentialofbiomassresourcesinruralChina:withspecialreferencesofcropresidues.RenewSustainEnergyRev2008;12:1402e18.

[19]JiangMM,ChenB,ZhouJB,TaoFR,LiZ,YangZF,etal.

EmergyaccountforbiomassresourceexploitationbyagricultureinChina.EnergyPolicy2007;35:4704e19.

[20]LiJF,HuRQ.Sustainablebiomassproductionforenergyin

China.BiomassBioenergy2003;25:483e99.

[21]ZhaoM,ZhouGS.Estimationofbiomassandnetprimary

productivityofmajorplantedforestsinChinabasedonforestinventorydata.ForestEcolManage2005;207:295e313.

[22]TangY,XieJS,GengS.Marginalland-basedbiomass

energyproductioninChina.JIntegratPlantBiol2010;52:112e21.

[23]LiaoCP,YanYJ,WuCZ,HuangHT.Studyonthedistribution

andquantityofbiomassresiduesresourceinChina.BiomassBioenergy2004;27:111e7.

[24]HoogwijkM,FaaijA,vandenBroekR,BerndesG,GielenD,

TurkenburgW.Explorationoftherangesoftheglobal

potentialofbiomassforenergy.BiomassBioenergy2003;25:119e33.

[25]MOA/DOEProjectExpertTeam.Assessmentofbiomass

resourceavailabilityinChina.Beijing,China:ChinaEnvironmentalSciencePress;1998.

[26]StatusandanalysisofgrowthanddeclineforForest

resource,http://sdinfo.forestry.ac.cn/000new/fzzl/5_1.cfm[accessed18.08.10].

[27]MaindataoftheSixthNationalForestrySurvey.http://www.

forestry.gov.cn/portal/main/s/65/content-90.html[accessed18.08.10].

[28]TheSeventhNationalForestrySurvey:increasingPressure

onprotectionmanagementofwoodland.http://www.farmer.com.cn/news/nyxw/201006/t20100612_5241.htm[accessed18.08.10].[29]Nationalforestareareached19500Â104hawithforestcover

rateat20.36%,http://www.gov.cn/wszb/zhibo3/content_1465744.htm[accessed18.08.10].

[30]Chinarealizedtheforestcoverareagoaltwoyearsaheadof

schedule,http://www.gov.cn/wszb/zhibo3/content_1465751.htm[accessed18.08.10].

[31]McKendryP.Energyproductionfrombiomass(part1):

overviewofbiomass.BioresourTechnol2002;83:37e46.

[32]NationalBureauofStatisticsofChina.Environmentalstatistics

yearbookofChinain2008.Beijing,China:StatisticsPress;2008.[33]StateEnvironmentalProtectionAdministrationofPollution

ControlDepartment.MSWmanagementandtreatmenttechnology.Beijing,China:ChinaPetroleumandChemistryPress;2000.

[34]ZhenX,YangY,LeiX.AnalysisofpowerpotentialfromMSW

sanitarylandfillgases.EnvironProt2009;414:19e22[inChinese].

[35]WangYJ.Discussionofmarketprospectofmunicipalsolid

wasteincineration.GuangdongScienceandTechnology2009;214:205e6[inChinese].

[36]TilmanD,HillJ,LehmanC.Carbon-negativebiofuelsfrom

low-inputhigh-diversitygrasslandbiomass.Science2006;314:1598e600.

[37]LiY.LandresourcesofChina.Beijing,China:DadiPress;2000.[38]HellerMC,KeoleianGA,MannMK,VolkTA.Lifecycleenergy

andenvironmentalbenefitsofgeneratingelectricityfromwillowbiomass.RenewEnergy2004;29:1023e42.

[39]DiX,NieZ,YuanB,ZuoT.Lifecycleinventoryforelectricity

generationinChina.IntJLifeCycleAssess2007;12:217e24.[40]http://www.chinapower.com.cn/newsarticle/1108/

new1108712.asp[accessed18.08.10].

[41]HuangY.EmissionsofgreenhousegasesinChinaandits

reductionstrategy.QuatSci2006;26:722e32[inChinese].[42]NationalClimateChangeStrategyCoordinatingGroup.People’s

RepublicofChinainitialnationalcommunicationonclimatechange.Beijing,China:ChinaPlanningPress;2004.13e22p.