Carbon emission reduction with high pressure underground coal gasification

Abstract

This chapter describes the work that has been done on high-pressure underground coal gasification (UCG), and outlines how a combination of UCG and CO2 capture and storage (CCS) could be a practical and cost effective route towards near zero emission power generation from coal. UCG is a process which lends itself to CO2 capture both from the high-pressure product gas and from subsequent downstream processing, using existing process technology. UCG as a power generating technology is likely to fall under the Greenhouse Gas Emissions Trading Directive, which would provide an early incentive for UCG to be developed in association with CCS. Many processes are available for the capture of CO2 based on physical or chemical absorption and separation membranes. CO2 capture in pre-combustion syngas is more energy efficient than the post-combustion process that removes CO2 from the flue gases of the combined cycle. The chapter considers three options for CO2 capture from UCG product gas. The comparative costs of electricity and CO2 capture have been undertaken as a preliminary scoping exercise for UCG power plant. UCG product gas can be readily converted into hydrogen and CO2, through the shift and capture processes. UCG with CCS is a practical alternative to natural gas reforming as a source of zero emission hydrogen for stationary or transportation fuel cells.