Thermal economy analysis of utilizing coalmine methane energy

Coal is the primary energy resource in China, with the raw coal production reaching 2.8 billion tons in 2008. However, great amount of coalmine methane is released during coal exploitation, which runs up to over 3.5 billion cubic meters. To minimize environmental pollution caused by coalmine methane and to promote resource utilization, various systems for utilizing coalmine methane energy are developed in China. Common types of such systems include power generation system utilizing coalmine methane, combined-heat-and-power system of coalmine methane, thermal energy provision system of coalmine methane, and fuel-gas provision system, etc. This paper describes elements, characteristics, and applicability of these systems and presents thermal economy analysis to specific system. Thermal economic indexes, such as exergic efficiency and exergic losses of specific coalmine methane energy utilization system are obtained. These data are very useful in finding the way to make further progress in improving thermal economy of coalmine methane energy utilization systems as well as providing technical support to make tradeoffs among those systems. In addition, the possibility of serving coalmine methane energy utilization systems as distributed energy resource is discussed and potential problems summarized. Generally speaking, these efforts are practical to promote coalmine methane energy utilization in China.