煤制天然气碳排放全生命周期分析及横向比较

在中国天然气市场需求旺盛、供需缺口快速扩大的大背景下，煤制天然气（SNG）迎来了大规模的投资与发展热潮。然而，随着“低碳经济”发展模式的转变预期，SNG又面临着“低碳”与否的争议。为此，采用全生命周期（LCA）评价方法对SNG项目从原煤开采到转化为煤制天然气、直至进入终端消费全过程的直接和间接二氧化碳排放及其温室气体排放进行了清单分析。同时，对SNG与煤层气、液化天然气、管输天然气的全生命周期二氧化碳排放清单进行了横向比较，将相关产业链划分为国外和国内两个环节并进行分析，结果认为LNG在国际贸易中具有明显的碳减排优势。结合美国大平原SNG工厂碳减排对我国的启示，提出中国发展SNG的“低碳”途径与选择，并呼吁应从多方面谨慎对待具体SNG项目的前期规划和研究。

Life cycle assessment of carbon emission from synthetic natural gas (SNG) and its horizontal comparison analysis

While the present demand for natural gas is rapidly increasing and the supply demand gap is being enlarged in China, the synthetic natural gas (SNG) is coming into its high time of scale investment and fast development. However, from the perspective of low carbon economy, a controversial issue is presented before the fast development of the SNG. Therefore, a life cycle assessment (LCA) is adopted to make a checklist analysis of direct or indirect CO2 and greenhouse gas emission involved in the whole process of SNG projects from the mining of raw coal to the production of SNG and even to the fuel of end users. Furthermore, a horizontal comparison is made of the CO2 emissions listed altogether from the SNG, coalbed methane（CBM）, LNG, and pipeline natural gas （PNG）respectively. And through a study of the related industrial chain divided into the foreign and the domestic part, it is thought that LNG trade has the obvious advantage in carbon emission reduction over the other three gases in the global trade. In combination with the practical experience gained in carbon emission reduction during the operation of the Great Plains Coal gasification in the U.S.A, it is suggested that more options of low carbon emission should be made for the fast development of SNG in China and the pre planning and investigations of a concrete SNG project should be carefully handled with.