Seminarium Fizyki Ciała Stałego

Underground coal gasification (UCG) is a gasification process used to produce gas from coal in situ (underground in the coal seam) by injecting air or oxygen, with or without steam, into coal seams and extracting the product gas via surface wells. The resulting synthetic gas (“syngas”) can be used to produce electricity, as well as chemicals, liquid fuels, hydrogen and synthetic natural gas. Oxygen is injected to feed the combustion and drive the gasification reactions that produce a gas mixture made chiefly of hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), and some amount of methane (CH4). These gases are then forced out a second borehole to be harnessed at the surface. The gasification of coal in this manner creates an empty cavity below ground, the size of which depends on the rate of water influx from the water table, the heat content of the coal, the location and shape of the injection and production wells, and the thickness of the coal seam.Underground coal gasification presents certain environmental advantages over conventional coal mining. By not requiring mining, UCG avoids issues such as acid mine runoff, mine safety, overuse of groundwater, and land reclamation. During gasification, approximately half of the sulfur, mercury, arsenic, tar and particulates from the used coal remain below ground. UGC syngas also has a higher hydrogen concentration than surface produced syngas, giving it a potential cost advantage when producing electricity.