Agroforestry Residues And Energy Crops Resources Assessment And The Associated Greenhouse Gas Emission Reduction Potentials In China

Biomass,as the only carbon-contained renewable energy,was a significant part of combating climate change due to its potential to achieve negative carbon emission.An accurate assessment of the total biomass resources as well as spatial distribution can provide support for the development and distribution of biomass industry in China.Meanwhile,the analysis of biomass application potential under technical constrains and its associated greenhouse gas（GHG）emission reduction will provide basic data and useful information for the achievement of national emission reduction target as well as biomass industry expansion.There are abundant agricultural and forestry residues in China.In addition,energy crops which grow on marginal land can also be tremendous.Biomass resources have a huge utilization potential in China.However,recent resource potential evaluation studies only considered the geographic constraints and lacked the consideration of energy converting efficiency of different biomass technologies.Meanwhile,they used relatively rough collecting parameters in the assessment,which may not reflect the collecting characteristics of different kinds of biomass.All of these will reduce the accuracy of resources assessment and create barriers for the development of biomass industry and policy formulation.Based on the 2000²015 mean Net Primary Productivity（NPP）datasets in China,this study combined a crops collecting model to build the resource assessing model for agroforestry residues and energy crops based on Geographic Information System（GIS）.A set of collecting parameters which precisely embodied crops geographic properties,were adopted to improve the accuracy of resources assessment in this model.Besides,the biomass application potential in China was estimated considering the current biomass technologies status.In addition,combining scenario analysis and Life Cycle Assessment（LCA）,the biomass resource related GHG reduction potentials under both current technology pathways（traditional technology scenario）and BioEnergy with Carbon Capture and Storage（BECCS）pathways（negative emission scenario）were evaluated in this study.The main findings are as follows:（1）Within the geographic constraints,the total energy potential of agroforestry residues and energy crops was estimated at 10.75¹1.45 EJ/yr,in which energy potential of agricultural residues was dominated as 9.10 EJ/yr（about 83%）.When the crops collecting range was 10km,eastern Sichuang,western Chongqing,eastern Shandong and eastern Jiangsu were the optimal regions with plants capacity of 30 kt/yr for biomass industry distribution.As for 50km scenario,two regions,eastern Sichuang and eastern Jiangsu were the optimal regions,where the government could develop biomass plants with capacity of 600 kt/yr.（2）Considering the energy conversion efficiency of current biomass technologies,the total energy potential of agroforestry residues and energy crops was estimated at 3.36³.58EJ/yr in China,which can meet the bioenergy demand in 2020 as reported in the 13^th five-year plan for biomass energy development.However,there still will be a big gap（2.63³.97 EJ/yr）if compared with bioenergy demand in 2030.To fill this gap in the future,optimizing current biomass pathways and developing more advanced biomass technologies are suggested.（3）Considering the life cycle GHG emissions of current biomass technologies,the utilization of agroforestry residues and energy crops can reduction 405⁴31 Mt CO₂/yr in traditional technology scenario,accounting for 4.45⁴.74%of China`s total GHG emissions in 2016.There was a significant GHG cutting potentials in negative emission scenario,which can reduce 1.38¹.47 Gt CO₂/yr,occupied 15.18¹6.17%of total GHG emission in 2016.Evaluation results also shows the national GHG reduction target（150 million t CO₂/yr）in2020 can be achieved by using biomass energy as a substitute for fossil fuels.