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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
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
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.
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