Invention Of UCG

Coal is the predominant fossil fuel on the earth as measured by total heat content yet there is much coal that cannot be mined by conventional methods because of various physical, economical and/or safety factors. There has been limited success in recovering the heating value of some unmissable coals by the underground partial combustion and gasification of the coal and the delivery of the resulting combustible gas to the surface for use. However, it has been concluded by many workers in the field that underground coal gasification must be restricted to non-swelling coals because the expansion of a swelling coal induced by the heat from the underground combustion will plug the channels or linkage between the wells through which the combustion gases are flowing and stop the combustion