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About ten feet of plant debris will produce one foot of coal. Since plant debris accumulates very slowly, it could take thousands of years fifty feet of plant debris to turn into a five-foot-thick seam of coal. During that time, the water level must be stable. If too deep, the swamp will drown and if too shallow, the plants will decay. In order for a coal seam to be formed, the water level must be maintained for a long period of time.
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Anthracite is a shiny, hard, black coal that burns with a smokeless blue flame. Most forms of coal are associated with sedimentary rock, but anthracite undergoes metamorphism and is linked to metamorphic rocks.
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It is widely used today in power stations today to make electricity. With less polluting and lower cost technologies arising, coal is becoming less popular in power plants to hydroelectricity and natural gas.
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In the United States, coal is primarily used to produce electricity. It is transported to a power plant, crushed and then burned. The heat from the burning coal is used to produce steam. The steam is used to spin a turbine which is connected to an electrical generator. The mechanical energy transforms into electric energy.
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Most electricity consumed today in the United States is made by burning coal.
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When coal is heated under controlled conditions in the absence of air, coke is produced. This process drives off some of the volatile materials and concentrates on the carbon content. Coke is used for metal processing and for other uses when a hot burning flame is needed.
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Coal is used in manufacturing plastics, synthetic rubber, linoleum, insecticides, medicines, solvents and paint products to name a few.
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Coal can be converted into liquid form and gaseous fuels; however, these uses of coal are experimental and not common.
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The world's top producer of coal is China. Other large producers are United States, India, Europe and Australia.
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Up until a few decades ago, most coal was used for space heating. While it is still used that way, other fuels and coal-produced electricity are used instead.
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Coal mining and burning of coal can have bad effects on the environment. Examples of this include acid rain and smog. Those toxins leaked into the air then lead to numerous respiratory effects and increased risks of lung cancer for coal plant workers.
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