Underground coalgasification: Moving towards commercialisation

Powering the future is the greatest environmental, economic and social challenge we face today. Despite the current trends towards shifting to renewable energy, fossil fuels and in particular coal, will continue to be a major source of energy for a period of time in the future – a 20% increase in coal demand is predicted between 2008 – 2035 [1]. Underground coal gasification (UCG) is an emerging process which permits access to coal seams which either lie too deep underground, or are otherwise too costly to be exploited using conventional mining technologies (i.e. open cast). The process involves the injection of an oxidation agent (H2O, O2, N2, CO2, or a mixture of these) into an underground coal seam, ignition and combustion of coal in-situ to produce a synthesis gas that can be used as a fuel for power generation or chemical feedstock. Many studies proved its potential advantages over the conventional mining methods, like increase in coal utilisation efficiency and the improvement of economic performance with simultaneous minimisation of environmental emissions as compared to the currently employed coal utilisation technologies. Although the idea of the underground coal gasification is not new and dates back about 100 years, renewed interest in UCG technology has recently occurred in most coal producing regions of the world. The present study reviews where UCG development has reached around the world and the role it could play in energy supplies, taking into account the current initiative for moving to a low carbon future.