10 - Coal mine methane: Control, utilization, and abatement

Abstract

World coal production in recent years has reached almost 8 billion tonnes per year. At this rate, coal and methane gas released from coal are likely to remain a dominant source of energy for decades. Raw coal includes impurities; however, methane gas does not. Coal mine methane (CMM) is the term given to methane gas emitted due to coal mining activities either from the coal seam or from other gassy rock formations. Capturing CMM offers a unique opportunity to mitigate greenhouse gas emissions and simultaneously increase available energy supply. CMM emissions can adversely affect both safety and productivity of underground coal mines. Ventilation is essential to circulate fresh air across active faces of underground coal mines. It is also a universal methane control technique. When ventilation systems cannot dilute CMM emissions to levels below statutory limits, supplemental methane drainage systems must be used. These coal mine degasification systems were developed to improve worker safety in mines. Apart from environmental concerns and productivity improvements, capturing CMM has many economical benefits that can justify and offset investment costs. CMM is most often used for power generation, district heating, or boiler fuel; but it can also be used as town gas or sold to natural gas pipeline companies. Moreover, CMM has the potential to provide a clean burning fuel for use at the mine site. Hence, CMM that was once a waste product and solely a miner's curse, is now a valuable byproduct, provided that it can be properly controlled and managed.