Geothermal energy uses the heat from under the earth's surface.

Have you ever seen pictures of a volcano or a geyser? If so, then you've seen geothermal energy in action!

"Geo" means "from the earth," and "thermal" means "heat," so this type of energy is found under the earth. The hot lava from a volcano and the hot steam from a geyser both come from underground heat. We can use that same type of heat in our homes.

illustration of a geothermal system

Here's how it works:

About four feet underground, the temperature of the earth stays the same all year long, about 55 degrees.

A geothermal heating system uses pipes buried more than four feet deep in the earth. The system pumps a liquid through the pipes to absorb the heat and brings it back indoors. A device called a heat exchanger takes the heat from the liquid and uses it to heat the air inside the home.

A geothermal system can cool your house during the summer, too! It just works in reverse, absorbing the heat from the air inside your home and moving it back into the earth.

A geothermal heater is very energy-efficient. Almost none of the energy used is wasted, so it helps keep heating bills very low during the winter.

Geothermal at school

Schools all over the Midwest are using geothermal energy for heating and air conditioning. Geothermal is great for schools because it uses a lot less energy than other types of heating and cooling equipment.

Electricity from under the earth

We can also use geothermal energy to make electricity. A geothermal power plant works by tapping into steam or hot water reservoirs underground. The heat is used to drive an electrical generator.

Most geothermal plants are located in the western United States, where hot water reservoirs are common. The Geysers power plant in northern California is the world's largest geothermal power plant, producing enough electricity to light up more than 22,000 homes.

Want to learn more about geothermal energy?

Check out the Energy Information Administration's Energy Kids website.