LCA-based environment and economic assessment of UCG coupled with CCS for methanol production

A coupled system that consists of underground coal gasification (UCG), carbon capture and storage (CCS), and syngas to methanol is of significant importance in solving the problems, such as the difficulty of deep coal mining and inability to utilize in-situ, as well as high carbon emissions during the mining and utilization process. However, there is a lack of sufficient data support for the environmental and economic assessment on this system, and the dynamic analysis of carbon reduction potential and core device CCS operating benefits of this system is rarely reported. This paper quantitatively evaluates environmental and economic benefits of the system by LCA method, discusses the influences of CCS on the characteristic indicators, and analyzes the dynamic characteristics of carbon reduction by CCS and the changes of CCS operating profits with carbon reduction. The results reveal that CCS has a significant impact on the key environmental indicators and external cost of the system, and its return ratio is more than 100 % after running 6 years when considering carbon credit pricing. This article provides important references for deep coal mining and utilization, as well as the field of coal chemical industry.