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. 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. 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. The earliest recorded mention of the idea of underground coal gasification was in 1868, when Sir William Siemens in his address to the Chemical Society of London suggested the underground gasification of waste and slack coal in the mine. Russian chemist Dmitri Mendeleyev further developed Siemens' idea over the next couple of decades. In 1909–1910, American, Canadian, and British patents were granted to American engineer Anson G. Betts for 'a method of using unmined coal'. The first experimental work on UCG was planned to start in 1912 in Durham, the United Kingdom, under the leadership of Nobel Prize winner Sir William Ramsay. However, Ramsay was unable to commence the UCG field work before the beginning of the World War I, and the project was abandoned. In 1913, Ramsay's work was noticed by Russian exile Vladimir Lenin who wrote in the newspaper Pravda an article 'Great Victory of Technology' promising to liberate workers from hazardous work in coal mines by underground coal gasification. Between 1928 and 1939, underground tests were conducted in the Soviet Union by the state-owned organization Podzemgaz. The first test using the chamber method started on 3 March 1933 in the Moscow coal basin at Krutova mine. This test and several following tests failed. The first successful test was conducted on 24 April 1934 in Lysychansk, Donetsk Basin by the Donetsk Institute of Coal Chemistry. The first pilot-scale process started 8 February 1935 in Horlivka, Donetsk Basin. Production gradually increased, and, in 1937–1938, the local chemical plant began using the produced gas. In 1940, experimental plants were built in Lysychansk and Tula. After World War II, the Soviet activities culminated in the operation of five industrial-scale UCG plants in the early 1960s. However, Soviet activities subsequently declined due to the discovery of extensive natural gas resources. In 1964, the Soviet program was downgraded. As of 2004 only Angren site in Uzbekistan and Yuzhno-Abinsk site in Russia continued operations. After World War II, the shortage in energy and the diffusion of the Soviets' results provoked new interest in Western Europe and the United States. In the United States, tests were conducted in 1947–1960 in Gorgas, Alabama. From 1973–1989, extensive testing was carried out. The United States Department of Energy and several large oil and gas companies conducted several tests. Lawrence Livermore National Laboratory conducted three tests in 1976–1979 at the Hoe Creek test site in Campbell County, Wyoming.