Uses of Coal
Coal is a combustible, organic rock composed primarily of carbon, hydrogen, and oxygen. Coal creates fuel that is used to heat buildings and to make various by-products. The main use of coal is in the production of electricity. About half of the electricity in the United States, and two-thirds of that in the world, is supplied by coal-burning power plants. Coke, a product left after heating coal, is used to manufacture iron and steel.
Coal was once the main source of energy in all industrial countries. However, petroleum and natural gas have become leading sources of energy. But, these supplies of fuel are being used up rapidly. The coal supply can last up to 400 years at the present rate. The use of coal, especially for producing electricity, could help relieve the shortage of gas and oil. However, some problems exist with the use of coal including air pollution and safety issues in mining deep underground.
Coal was created millions of years ago.   It was formed from trees and other plants that once flourished in swamps.  As this organic material died, it settled in the bottom of the swamp. Layers of sediment and mud accumulated, pressing down on the once living material.  The combination of a loss of oxygen and millions of years of weight from the earth pressing down resulted in rich veins of coal. The amount of pressure varies in places around the world.  The more pressure, the more carbon in the coal and the coal is harder. Less pressure results in less carbon and more moisture. The softest coal, with the least amount of carbon and most moisture, is peat. Peat is often associated with Ireland and is found near the top of the earth and cut out like bricks. The hardest coal is anthracite.  If the deposits of anthracite coal waited another million years, they would become diamonds.

The use of coal depends on its chemical composition and how much moisture it contains. It is usually classified according to the amount of fixed carbon in the coal. As the amount of moisture increases, the coal has a lower heating value.
Coal is useful as a fuel because it is abundant as well as having a relatively high heating value. However, impurities can cause air pollution which limits the usefulness of coal as a fuel.  Many manufacturers changed to natural gas in making their products but are now switching back to coal because it is less expensive. Coal is a non-renewable resource and must be conserved the same as petroleum and natural gas.
Coal is used for many things in addition to fuel for heating homes or running engines.  Products left after heating coal are coke and coal tar.  Coke is used as a fuel in steel mills and pencil lead is also made from coke.  Coal tar is a dark, sticky substance used in making plastics, perfumes, mothballs, medicine, dyes, explosives and flavorings.
Grades of Coal
Anthracite – this type of coal has the highest percentage of fixed carbon and a lower percentage of volatile material than all other coals, making it harder to ignite. However, when it is ignited, it burns relatively smokeless.  Anthracite coal is the most difficult to mine, since it is so hard.  In addition, there are not many accessible veins of anthracite coal. The most well-known anthracite mines in the United States are in western Pennsylvania.  While the use of anthracite as a fuel for heating has declined over the years, its high carbon and low sulfur content have increased its use for chemical and metallurgical purposes.
Bituminous – Bituminous coal is the most abundant and most widely used coal. This is the type of coal found in the Appalachian region. It has a higher heating potential and is used for making coke. It has a higher percentage of fixed carbon, greater heat value and better weathering characteristics than lignite and sub-lignite coals. According to geological estimates, seven feet or more of compacted plant life was required to form one foot of bituminous coal. All of the grades of coking coal that are used for metallurgical purposes fall within the bituminous classification. Most of the non-metallurgical grades of bituminous coal are burned in boilers or furnaces to obtain thermal energy for generating electricity. Because bituminous coal is softer than anthracite, it is often referred to as soft coal.  It does emit smoke as it burns, unlike anthracite. However, there is a region in Southern West Virginia where the bituminous coal burns relatively smokeless. The Smokeless Coal Fields of Southern West Virginia are unique in the world.
Sub-bituminous – A lesser grade of coal, it has more moisture and less carbon than bituminous.
Lignite - The lowest grade of coal, lignite is formed from layers of sediment that accumulates over peat. While it is more combustible than peat, it still has more moisture and less carbon than other grades of coal.