Coal is a fossil fuel formed from the remains of plants that lived and died hundreds of millions of years ago, when parts of the Earth were covered with huge swampy forests. Coal is called a nonrenewable energy source because it takes millions of years to form. The energy we get from coal today came from the energy that plants absorbed from the sun millions of years ago. All living plants store energy from the sun. After the plants die, this energy is usually released as the plants decay. Under certain conditions, however, the decay is interrupted, preventing the release of the stored solar energy. 100—400 million years ago, plants that fell to the bottom of the swamp began to decay as layers of dirt and water were piled on top. Heat and pressure from these layers caused a chemical change to occur, eventually creating coal over time.

Americans used coal long before the first settlers arrived in the New World. Hopi Indians used coal to bake the pottery they made from clay. European settlers discovered coal in North America during the first half of the 1600s. They used very little coal at first. Instead, they relied on water wheels and burning wood to power colonial industries. Coal became a powerhouse by the 1800s. People used coal to manufacture goods and to power steamships and railroad engines. By the time of the American Civil War, people also used coal to make iron and steel. And by the end of the 1800s, people began using coal to make electricity. Today, coal provides one-fifth (20.2 percent) of America’s energy needs. Almost 42 percent of our electricity comes from coal-fired power plants.