Deep coal beds underlie cities like Calgary and Edmonton in Alberta. The amount of energy in this coal rivals the energy contained in the oil sands. This energy can be realized at the surface through a process of “underground coal gasification”
Engineers have long known how to gasify coal above ground – turn it into syngas, a mixture of hydrogen, carbon monoxide and carbon dioxide. The same is accomplished with underground coal gasification, but without the mining or the gasifier machinery.
Air or oxygen is injected into wells that penetrate a deep coal seam, where controlled partial combustion drives gasification. The gases are brought to the surface, leaving behind many of the objectionable components, including roughly half the coal’s sulphur, ash, tar, mercury and arsenic. On the surface, this operation looks like nothing more than a network of wellheads and pipes. But the huge quantities of gas produced can either be burned to generate electricity on site or piped off to make hydrogen, heat or synthetic fuels.
UCG (underground coal gasification) has been used for a long time. Today UCG projects are being developed in Australia, China and Canada. As a source of power for generating electricity UCG is cheaper than natural gas.
Canada is a UCG leader. Ergo Exergy, based in Montreal, has operated a pilot project at industrial scale in Australia and is running the largest current pilot at the Majuba coalfield in South Africa. The company is also developing a project near Edmonton that will provide low-carbon electricity, steam and hydrogen to tar-sands upgraders, as well as carbon dioxide for sequestration and enhanced recovery from exhausted oil fields. So is Calgary’s Swan Hills Synfuels, which is exploiting the deep Manville coal seam near Edmonton in partnership with the Alberta Energy Research Institute. http://www.theglobeandmail.com/servlet/story/RTGAM.20090501.wcocoal04/BNStory/specialComment/home