Underground coal gasification (UCG) has been around for a very long time, but just as it was about to surface as a potentially commercially viable alternative to traditional coal mining, the shale revolution stole the limelight.
But now we’re back to coal gasification again, because the new drilling technology that brought us the shale boom can be applied to UCG as well. Some even think it could outpace coal-bed methane in 2015 and have a palpable impact on global oil prices if it were to replace oil significantly in the US and China.
Underground coal gasification—also known as in-situ coal gasification or ISCG--is the process of converting raw coal that is still in the ground into a combustible gas that can be used for high value products like industrial heating, power generation, fertilizers or other chemical feedstocks, and manufacturing of syngas (synthetic natural gas or diesel fuel) or hydrogen.
Syngas—a mixture of hydrogen, carbon monoxide, carbon dioxide and methane--contains about 80% of coal’s initial energy content.
How It Works
As opposed to surface gasification, underground coal gasification uses the coal cavity itself as the reactor for the process. This involves the drilling of two wells into the coal bed. The first well is for injecting oxidants such as water or oxygen mixtures. The coal left at the base of the first well is heated and separated into syngas, which is drawn out of the second well.…