玉米秸秆基纤维素乙醇生命周期能耗与温室气体排放分析

Life cycle assessment of energy consumption and greenhouse gas emissions of cellulosic ethanol from corn stover

摘要:

生命周期评价是目前分析产品或工艺的环境负荷唯一标准化工具，利用其生命周期分析方法可以有效地研究纤维素乙醇生命周期能耗与温室气体排放问题。为了定量解释以玉米秸秆为原料的纤维素乙醇的节能和温室气体减排潜力，利用生命周期分析方法对以稀酸预处理、酶水解法生产的玉米秸秆基乙醇进行了生命周期能耗与温室气体排放分析，以汽车行驶1 km为功能单位。结果表明：与汽油相比，纤维素乙醇E100 (100％乙醇) 和E10 (乙醇和汽油体积比=1∶9) 生命周期化石能耗分别减少79.63％和6.25％，温室气体排放分别减少53.98％和6.69％；生物质阶段化石能耗占到总化石能耗68.3％，其中氮肥和柴油的生命周期能耗贡献最大，分别占到生物质阶段的45.78％和33.26％；工厂电力生产过程的生命周期温室气体排放最多，占净温室气体排放量的42.06％，提升技术减少排放是降低净排放的有效措施。

Abstract:

Life Cycle Assessment (LCA) is the only standardized tool currently used to assess environmental loads of products and processes. The life cycle analysis, as a part of LCA, is a useful and powerful methodology for studying life cycle energy efficiency and life cycle GHG emission. To quantitatively explain the potential of energy saving and greenhouse gas (GHG) emissions reduction of corn stover-based ethanol, we analyzed life cycle energy consumption and GHG emissions of corn stover-based ethanol by the method of life cycle analysis. The processes are dilute acid prehydrolysis and enzymatic hydrolysis. The functional unit was defined as 1 km distance driven by the vehicle. Results indicated: compared with gasoline, the corn stover-based E100 (100% ethanol) and E10 (a blend of 10% ethanol and 90% gasoline by volume) could reduce life cycle fossil energy consumption by 79.63% and 6.25% respectively, as well as GHG emissions by 53.98% and 6.69%; the fossil energy consumed by biomass stage was 68.3% of total fossil energy input, N-fertilizer and diesel were the main factors which contributed 45.78% and 33.26% to biomass stage; electricity production process contributed 42.06% to the net GHG emissions, the improvement of technology might reduce emissions markedly.