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Geothermal Energy and the Environment

Geothermal energy does little damage to the environment. Another

advantage is that geothermal plants don’t have to transport fuel,

like most power plants. Geothermal plants sit on top of their fuel

source. Geothermal power plants have been built in deserts, in the

middle of crops, and in mountain forests.

Geothermal plants produce almost no emissions because they do

not burn fuel to generate electricit

ƒ High Temperature Resources: Electricity

Hydrothermal resources at high temperatures (300 to 700 degrees

Fahrenheit) can be used to make electricity.

These high-temperature resources may come from either dry

steam wells or hot water wells. We can use these resources by

drilling wells into the Earth and piping the steam or hot water to

the surface. Geothermal wells are one to two miles deep.

In a dry steam power plant, the steam from the geothermal

reservoir is piped directly from a well to a turbine generator to

make electricity. In a hot water plant, some of the hot water is

turned into steam. The steam powers a turbine generator just like a

dry steam plant. When the steam cools, it condenses to water and

is injected back into the ground to be used over and over again.

Geothermal energy produces only a small percentage of U.S.

electricity. Today, it produces about 15 billion kilowatt-hours, or

less than one percent of the electricity produced in this country

Hydrothermal Resources

There is more than one type of geothermal energy, but only one

kind is widely used to make electricity. It is called hydrothermal

energy. Hydrothermal resources have two common ingredients:

water (hydro) and heat (thermal). Depending on the temperature of

the hydrothermal resource, the heat energy can either be used for

making electricity or for heating.

ƒ Low Temperature Resources: Heating

Hydrothermal resources at low temperatures (50 to 300 degrees

Fahrenheit) are located everywhere in the United States, just a few

feet below the ground. This low temperature geothermal energy is

used for heating homes and buildings, growing crops, and drying

lumber, fruits, and vegetables.

In the U.S., geothermal heat pumps are used to heat and cool homes

and public buildings. In fact, approximately 750,000 geothermal

exchange systems are installed in the U.S. Almost 90 percent of the

homes and businesses in Iceland use geothermal energy for space

heating