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Secunda CTL is a synthetic fuel plant owned by Sasol at Secunda, Mpumalanga in South Africa. It uses coal liquefaction to produce petroleum-like synthetic crude oil from coal. The process used by Sasol is based on the Fischer–Tropsch process. It is the largest coal liquefaction plant and the largest single emitter of greenhouse gas in the world.
Underground coal gasification (UCG) is an industrial gasification process, which is carried out in non-mined coal seams. It involves injection of a gaseous oxidizing agent , usually oxygen or air, and bringing the resulting product gas to the surface through production wells drilled from the surface.
Newly built coal-fired power plants can be made to immediately use gasification of the coal prior to combustion. This makes it much easier to separate off the CO 2 from the exhaust fumes, making the process cheaper. This gasification process is done in new coal-burning power plants such as the coal-burning power plant at Tianjin, called "GreenGen".
Typically coal liquefaction processes are associated with significant CO 2 emissions from the gasification process or as well as from generation of necessary process heat and electricity inputs to the liquefaction reactors, [10] thus releasing greenhouse gases that can contribute to anthropogenic global warming.
Air pollution in Africa is coming to the forefront and must not be ignored. For example, in South Africa the mercury levels are severe due to coal combustion and gold mining. Mercury is absorbed from the air into the soil and water. [19] The soil allows the crops to absorb the mercury, which humans ingest.
Air pollution emission factors are usually expressed as the weight of the pollutant divided by a unit weight, volume, distance, or duration of the activity emitting the pollutant (e.g., kilograms of particulate matter emitted per megagram of coal burned). The factors help to estimate emissions from various sources of air pollution.
The mining and processing of coal causes air and water pollution. [124] Coal-powered plants emit nitrogen oxides, sulfur dioxide, particulate pollution, and heavy metals, which adversely affect human health. [124] Coal bed methane extraction is important to avoid mining accidents. The deadly London smog was caused primarily by the heavy use of ...
The underground coal gasification process. Underground coal gasification converts coal to gas while still in the coal seam (in-situ). Gas is produced and extracted through wells drilled into the unmined coal seam. Injection wells are used to supply the oxidants (air, oxygen) and steam to ignite and fuel the underground combustion process ...