Coal the heat and pressure of deep burial causes the loss of water, methane and carbon dioxide and an increase in the proportion of carbon. Thus first lignite (also called "brown coal"), then sub-bituminous coal, bituminous coal, and lastly anthracite (also called "hard coal" or "black coal") may be formed. The wide, shallow seas of the Carboniferous Period provided ideal conditions for coal formation, although coal is known from most geological periods. The exception is the coal gap in the Permian–Triassic extinction event, where coal is rare. Coal is known from Precambrian strata, which predate land plants—this coal is presumed to
A. B. Brown Generating Station A. B. Brown Generating Station The A. B. Brown Generating Station is a four-unit, 700 megawatt (MW) power plant, located on the northern bank of Ohio River, east of Mount Vernon, Indiana and southwest of Evansville, Indiana just west of the Posey-Vanderburgh County Line. Each of the two coal-fired units has a name-plate capacity of 265.2 MW. Bituminous coal is used as a primary fuel type, which can be substituted for natural gas. There are also two gas turbine units, 88.2 MW of nameplate capacity each. The facility is owned by Vectren (formerly Southern Indiana Gas and Electric Company). In