Underground coal gasification
Underground coal gasification (UCG) is an industrial process which converts coal into product gas. UCG is an in-situ gasification process, carried out in non-mined coal seams using injection of oxidants and steam. The product gas is brought to the surface through production wells drilled from the surface.
| Process type | chemical |
|---|---|
| Industrial sector(s) | oil and gas industry coal industry |
| Feedstock | coal |
| Product(s) | coal gas |
| Leading companies | Africary Linc Energy Carbon Energy |
| Main facilities | Angren Power Station (Uzbekistan) Majuba Power Station (South Africa) Chinchilla Demonstration Facility (Australia) |
| Inventor | Carl Wilhelm Siemens |
| Year of invention | 1868 |
| Developer(s) | African Carbon Energy Ergo Exergy Technologies Skochinsky Institute of Mining |
The predominant product gases are methane, hydrogen, carbon monoxide and carbon dioxide. Ratios vary depending upon formation pressure, depth of coal and oxidant balance. Gas output may be combusted for electricity production. Alternatively, the gas output can be used to produce synthetic natural gas, or hydrogen and carbon monoxide can be used as a chemical feedstock for the production of fuels (e.g. diesel), fertilizer, explosives and other products.
The technique can be applied to coal resources that are otherwise unprofitable or technically complicated to extract by traditional mining methods. UCG offers an alternative to conventional coal mining methods for some resources. It has been linked to a number of concerns from environmental campaigners.