我国生物质能源现代化应用前景展望(四)——生物质能源转化生命周期分析

生物质种类不同,转化为运输燃料的途径也是多种多样,生命周期排放的温室气体和能耗也不相同。总结对比主要生物质转化途径的全生命周期分析(LCA)结果,有助于明确需要进一步改进的技术难题和方向。生物质转化为醇类燃料时,使用E85比使用传统汽油的碳排放明显下降,纤维素生化转化途径排放的二氧化碳当量值约为传统汽油的0.2~0.7倍,热化学途径约为传统汽油的0.6~0.9倍,玉米干法为传统汽油的0.8~1倍。油脂类生物质转化为酯类燃料时,生物柴油减排温室气体的效果,动物油脂地沟油、棕榈油豆油、椰子油菜籽油。动物油脂、地沟油生产生物柴油可减排温室气体70%~90%,以植物为原料的生物柴油可减排10%~90%。生物质转化为烃类燃料时,菜籽油基喷气燃料可减排温室气体13%~55%,F-T合成油比油脂加氢具有更好的减排效果,BTL通常可减排80%以上的温室气体,CBTL的减排效果与掺入生物质的比例有关,热解汽柴油的温室气体减排率为58%~70%。对于微藻生物燃料工艺过程,在微藻产率和含油量不太低的情况下,池子系统的温室气体排放低于石油柴油。

The Prospects for Modern Application of Biomass Energy in China （IV） --Analysis of Biomass Conversion Life Cycle

There are many different routes for converting biomass to transport fuels ,depending on the type of the biomass ,and the amounts of greenhouse gas emitted and energy used in conversion of different types of biomass during their life cycles also vary.A summarization and comparison between the results of full life cycle analysis for major biomass conversion routes helps identify technical challenges that need to be overcome as well as technical directions.When biomass is converted to alcohol fuels,E85 emits considerably lower amounts of carbon than traditional gasoline.The carbon dioxide equivalent emitted in cellulose biochemical conversion is about 0.2-0.7 times the carbon dioxide equivalent emitted in the process using traditional gasoline;that in the thermochemical route is about 0.6-0.9 times that emitted in the traditional gasoline route, and that in the dry maize method is 0.8-1 time that in the traditional gasoline route.When oil and grease biomass is converted to ester fuels,the efficiencies of reducing greenhouse gases by biodiesel derived from the following sources are ranked： animal fat 〉 gutter oil,palm oil 〉 soybean oil,and coconut oil 〉 rapeseed oil.Using animal fat and gutter oil to make biodiesel fuel can reduce greenhouse gas emissions by 70%-90% and using plant as raw material to make biodiesel fuel can reduce greenhouse gas emissions by 10%-90%. When biomass is converted to hydrocarbon fuels,using rapeseed oil to produce jet fuel can reduce greenhouse gas emissions by 13%-55%.The F-T synthetic oil process has better emission reduction effect than the grease hydrogenation process.The BTL process can usually reduce greenhouse gas emissions by over 80%. The emission reduction effect of the CBTL process is related to the proportion of biomass blended in.Gasoline and diesel fuel pyrolysis processes reduce greenhouse gas emissions by 58%-70%.In the microalgae biofuel process ,when the yield and oil content of microalgae are not too low,the greenhouse gas emissions of the pond system are lower