Flue-Gas Desulfurization

Flue gas desulfurization is a set of technologies that remove sulfur dioxide from the exhaust gases of fossil fuel power plants, incinerators, refineries and kilns, most commonly by scrubbing the gas with an alkaline slurry of limestone, lime or seawater; a well run installation at a coal fired power station can remove 90 percent or more of the sulfur dioxide present. Early concepts date to around 1850 in England, and the first major utility scale installation went into service at Battersea Power Station in London in 1931, but large scale adoption did not resume until the 1970s, driven mainly by the United States and Japan and, in the American case, by the Clean Air Act of 1970. By around 1999 to 2000, roughly 678 flue gas desulfurization units were operating worldwide with about 229 gigawatts of combined capacity, some 45 percent of it in the United States, 24 percent in Germany and 11 percent in Japan; about 79 percent of that capacity used wet limestone or lime scrubbing and about 18 percent used spray dry scrubbing or sorbent injection.