The letters following each Review Question refer to the corresponding Learning Objective from the Chapter Opener. What is coal-bed methane and how is it extracted? (C)

Coal-bed methane (CBM) is a type of natural gas, specifically methane, found in coal deposits. It is formed during the process of coalification, where plant material is converted into coal over millions of years under specific conditions. The methane gas is adsorbed into the coal seams and held in place by water pressure.

Coal-bed methane is formed through the same geological processes as coal. Dead plant materials are subjected to heat and pressure under the Earth's surface over millions of years. During this time, coal goes through several stages of transformation from peat to lignite, bituminous coal, and eventually, anthracite coal. Throughout this process, methane is generated and trapped within the coal seams. The amount of methane held in the coal bed can vary, depending on the depth, rank, and composition of the coal seam.

The process of extracting coal-bed methane involves the following steps: 1. Identifying suitable coal seams: Exploration activities are carried out to identify the presence of methane in coal deposits. This involves analyzing geological data and using advanced technologies to identify the ideal coal seams for extraction. 2. Drilling wells: Once a suitable location is identified, vertical or horizontal wells are drilled into the coal seams to access the methane gas held within. 3. Dewatering: In order to release the methane gas from the coal seam, the water pressure holding the gas in place must be reduced. This is achieved by pumping out the water from the coal seam, a process called dewatering. As the water is removed, the pressure within the coal seam decreases, allowing the methane gas to desorb from the coal. 4. Gas collection and transportation: The released methane gas then flows to the surface through the wellbore. This collected gas is then treated to remove any impurities and transported through pipelines to be used as a clean energy source. 5. Environmental management: Throughout the extraction process, various steps are taken to minimize the environmental impact of coal-bed methane production. This includes proper wastewater management, monitoring of groundwater quality, and the implementation of safety measures to prevent methane leaks. In summary, coal-bed methane is a natural gas found in coal deposits, formed during the process of coalification. It is extracted by identifying suitable coal seams, drilling wells, dewatering to release the gas, and then collecting and transporting it to be used as an energy source.