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Underground coal gasification must also have carbon capture and storage
Trials of UCG (Underground Coal Gasification) under way globally from China to Queensland, and South Africa to Canada, the stakes are high. Not least for the atmosphere. Without a way to capture all the carbon and store it out of harm's way, it could raise the world's temperature by 10 degrees or more.
In the past decade, the focus has been on shale gas: methane tightly trapped in tiny pores and fractures in shale, a sedimentary rock made up of mud and clay mixed with minerals such as quartz. Capturing that gas required two crucial new technologies. Horizontal drilling launched from conventional vertical wells can penetrate for up to 3 kilometres along shale beds. And hydraulic fracturing, or fracking, blasts high-pressure water into the shale to fracture the rock and release the gas. As well as opening up the shale, these technologies open the door to a wide range of alternative sources of methane. They can release methane trapped within coal seams, for example, notably in the coalfields of Wyoming and Montana. Methane is often produced as seams develop, as the coal becomes compacted and heated deep underground. The gas has always been the bane of coal mining, but if collected and pumped to the surface, it becomes an asset.
Source: http://nextbigfuture.com/2014/02/underground-coal-gasification-must-also.html
