垃圾热化学转化利用过程中碳排放的两种计算方法

为了明确城市生活垃圾焚烧和热解两种热化学方式处理过程中温室气体的排放量(简称"碳排放"或GHG),分别采用生命周期评价方法(LCA)和政府间气候变化专门委员会(IPCC)制定的2006国家温室气体排放清单指南(简称"IPCC2006指南")进行了核算,并计算了两种垃圾热化学处理方式相对于填埋处理的GHG减排量.结果表明,两种核算方法计算所得的不同垃圾处理方式的碳排放趋势基本一致,但基于IPCC2006指南计算出的GHG减排量高于LCA方法的计算结果.相对填埋处理而言,焚烧处理的GHG减排量从LCA法的597～660kg(以CO2当量计,下同)提高到IPCC2006指南法的648～747kg;垃圾热解发电的GHG减排量从LCA法的535kg提高到IPCC2006指南法的589kg.同时,对这两种核算方法的特点及在我国的适用性进行了分析,研究认为LCA法和IPCC2006指南可以结合使用以促进我国GHG核算机制的完善.

Two calculation methods for greenhouse gas emissions from municipal solid waste thermo-chemical conversion and utilization processes

Different greenhouse gas (GHG) accounting methods may lead to different outcomes. In this work life-cycle assessment (LCA) and IPCC 2006 guidelines were applied to calculate GHG emissions from a municipal solid waste (MSW) landfill and two MSW thermo-chemical conversion processes: incineration and pyrolysis. Similar trends were found for the results from the two accounting methods, which show that both incineration and pyrolysis are more environmentally favorable than landfilling without landfill gas collection. Under LCA estimation, incineration and pyrolysis lead to 597~660 kg CO2-eq and 535 kg CO2-eq GHG savings, respectively; while calculated by the IPCC 2006 guidelines, incineration and pyrolysis lead to 648~747 kg CO2-eq and 589 kg CO2-eq GHG savings respectively. This increase related to the IPCC 2006 guidelines was analysed based on the calculation mechanism and the adaptabilities of both accounting methods in China were evaluated and compared. Joint use of IPCC 2006 Guidelines and LCA method in different cases is recommended for improvement of the accounting method and provision of default data for new technology such as pyrolysis.