Coal is a fossil fuel that is primarily composed of carbon, hydrogen, sulfur, nitrogen, and oxygen. It forms from the accumulation of organic material, primarily dead plants, in low-oxygen environments over millions of years. The organic material is subjected to high pressure and temperature over time, which causes the formation of coal.
There are four main types of coal: bituminous, sub-bituminous, lignite, and anthracite. Bituminous coal is the most abundant type and is used for energy production. Sub-bituminous coal is a lower grade of coal and is often used for electricity generation. Lignite is the lowest grade of coal and is typically used for energy production near the site of mining. Anthracite is the highest grade of coal and is used for heating and industrial purposes.
Coal is primarily found in sedimentary rocks and is typically associated with coal basins, which are regions of the Earth's crust where coal has formed and accumulated. These basins are found in several countries, including the United States, China, Australia, and Russia. The extraction of coal involves removing the rock layer above the coal seam and then removing the coal itself.
Coal has been an important energy source for centuries, but its use has decreased in recent years due to environmental concerns, such as the emission of greenhouse gases and air pollution. However, it remains a significant source of energy, particularly in developing countries.