Coal, a fossil fuel, is a combustible sedimentary rock composed mostly of carbon and hydrocarbons. Most coal is used to generate electricity, however, it’s also used as a basic energy source in many industries, including, steel, cement and paper.

What is coal?

Coal is a nonrenewable energy source because it takes millions of years to create. It is a combustible black or brownish-black sedimentary rock composed mostly of carbon and hydrocarbons. The energy in coal comes from the energy stored by plants that lived hundreds of millions of years ago, when the earth was partly covered with swampy forests. For millions of years, water and dirt buried layers of the dead plants at the bottom of the swamps, trapping the energy of the dead plants. The heat and pressure from the top layers helped the plant remains turn into what we today call coal. Coal is part of the fossil fuels family.

How is coal formed?

Coal formation began during the Carboniferous period (280 to 345 million years ago).  Much of the earth was covered with swamp during this time, and large amounts of plants and other organic matter grew. As the plants and other life forms died, they sank to the bottom of the swampy areas. They slowly decomposed, and formed peat—a soggy, dense, sponge-like material. Over time, the peat was buried and compressed under the earth’s surface. As the earth’s surface changed over millions of years, sand, clay and other minerals accumulated, burying the peat. Layer upon layer created heat and pressure, which compressed the peat into a hard substance we call coal.

Where is coal found?

Some coal beds lie within 200 feet of the earth's surface. These beds are mined by stripping the top soil off the coal. Then the coal is dug out. This is called surface mining. Deeper coal beds can be found up to one thousand feet below the earth. Miners tunnel underground to get this coal.The US has the largest coal reserves, followed by the Russian Federation, China, and Australia.

How is coal extracted?

Coal is extracted from the ground by mining underground or at the surface. Coal mines are many miles wide.  First, dirt above the coal deposit is removed. Coal is found in thick, flat layers. Explosives are then used to break the exposed coal into smaller pieces. The coal is then loaded into a wagon and lifted to the surface.

History of coal

Archiological evidence indicates that the Romans in England used coal in the second and third centuries (100-200 AD). It was used in the 1300s by Native Americans for cooking, heating and baking pottery. Read more.

Uses for coal

In some countries, coal may be burned directly for heat or cooking, but most coal is used in power plants to generate electricity. Coal-burning power plants can be sources of air emissions, generating substantial greenhouse gases. New technologies significantly reduce these emissions.

Demand for coal

Worldwide coal reserves are slightly more than one trillion tons—enough to last approximately 180 years at current consumption levels. The countries with the largest reserves of coal are the United States, Russia, China, and India. Together they make up 67% of the world’s coal reserves.

Coal provides 26% of global primary energy needs and generates 41% of the world's electricity, according to the World Coal Institute Coal Facts 2008. The US Energy Information Administration expects coal use to double by 2030 to meet rising world energy demand.

Coal pros and cons

Pros

• Abundant supply
• Currently inexpensive to extract
• Reliable and capable of generating large amounts of power

Cons

• Emits major greenhouse gases/acid rain
• High environmental impact from mining and burning, although cleaner coal-burning technology is being developed

More coal resources

World Coal Institute - Includes information on coal processes and technologies, careers, and environment and safety.

American Coal Council - Defines coal, offers career information and speaker resources

Coal Association of Canada - Discusses Canada's coal industry, coal quick facts, environmental impact and career information.