Millions of years ago, the remains of plants and animals decayed and built up in thick layers. Over time, this organic material changed into coal, oil and natural gas.
Coal is by far the most abundant fossil fuel on earth. It is mainly used as a combustion fuel. The large-scale use of coal began with the Industrial Revolution in the 19th century. As the number of industries increased, demand for more sources of energy grew.
There are three main types of coal: lignite, bituminous, and anthracite. Lignite and bituminous have a lesser percentage of carbon in them and therefore burn faster. They release a great deal of pollutants into the atmosphere. Anthracite has about 98 percent carbon and therefore burns slowly and releases much less smoke.
Power plants burn coal to generate electricity. When coal is baked in hot furnaces, it is used to smelt iron ore into iron needed for making steel. Coal can also be used to produce plastics, tar, synthetic fibers, fertilizers and medicine.