More than 150 years ago, wood supplied up to 90 percent of the nation’s energy needs.

More than half of renewable energy sources are devoted to producing electricity.

In 2009, consumption of renewable sources in the United States totaled about 8 percent of all energy used nationally.

Fossil fuels formed in similar ways hundred,hundred of millions of years ago, before the dinosaurs. Then the earth was mostly shallow seas and swampy forests

Fossil fuels are a valuable source of energy. They are relatively cheaply to extract. They can also be stored, piped, or shipped anywhere in the world.

About half the electricity in the United States comes from coal.

When coal is burned, it releases many toxic gases and pollutants into the atmosphere.