Sources of Energy

We may use many different energy sources to do work for us. They are classified into two groups - renewable energy and nonrenewable energy .

In the United States, most of our energy comes from nonrenewable energy sources. Coal, petroleum, natural gas, propane and uranium are nonrenewable energy sources. They are used to make electricity, heat our homes, move our cars and manufacture all kind of products. These energy sources are called nonrenewable because their supplies are limited. Petroleum, for example, was formed millions of years ago from the remains of ancient sea plants and animals. We can't make more crude oil deposits in a short time.

Renewable energy sources include biomass, geothermal energy, hydropower, solar energy and wind energy. They are called renewable because they are replenished in a short time. Day after day, the sun shines, the wind blows and the rivers flow. We use renewable energy sources mainly to make electricity.