Geothermal energy can also be captured from heat pumps. Heat pumps tap
into the heat near the Earth’s surface. This type of energy capturing can be
used to heat water supplies or heat/cool buildings. Geothermal heat pumps
transfer heat by pumping water or a refrigerant through pipes (also known as
heat exchangers) below the Earth’s surface. During the winter months the water
and refrigerants absorb heat from the Earth and deliver it to buildings and
such. During summer months pumps are able to run oppositely and facilitate with
cooling buildings. This requires indoor air to be removed into the heat
exchanger. Additionally the heat removed from the indoor air can be used to
heat water for free. Once heat is transferred the water or refrigerant is
pumped back underground where the whole process begins again.
In the United States the majority of geothermal reservoirs can be
found in western states, Alaska, and Hawaii. There are also only two known underground resources of steam in the
United States (that are capable of running dry steam power plants).
They are the Geysers in
California, and Old Faithful in Yellowstone National Park in Wyoming. However,
because Yellowstone National Park is protected from development, their
underground resource of steam cannot be used.
Today scientists are still searching for a technology that allows for
extracting heat directly from magma, which is considered the most powerful form
of geothermal energy.