Dirty fuels

   Coal is the cheapest and most abundant energy source in the United States. However, coal is a dirty fuel. The smoke from burning coal contains large amounts of sulfur and carbon dioxide. Surface mining destroys the land environment. Drainage from surface mining pollutes water.
   Oil is the major source of gasoline and other liquid fuels used for transportation and heat. The United States must import 40 to 45 percent of its oil supply. Burning oil also adds pollutants to the atmosphere, such as carbon dioxide, sulfur dioxide, and other gases. The production and transportation of oil can also pollute the environment, especially if an oil spill occurs.
   Natural gas is the cleanest-burning fossil fuel. It generates fewer air pollutants and less carbon dioxide than other fossil fuels do. Gas is an efficient fuel and is used a great deal in industry, transportation, and power generation.