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Journey
to the center of the earth (well...not quite) to explore more about
one of the hottest energy resources around. Geothermal power takes
advantage of the Earth’s core heat to produce useable energy.
How will your energy mix use geothermal?
Geothermal
energy is energy we capture from heat stored in the Earth.
Uses
Geothermal
power is used in two main ways: (1) for heating and cooling (2)
to generate electricity. Underground temperature determines which
of the applications is used.
Heating
and Cooling
 At
a certain depth, the underground temperature remains relatively
constant. Using geothermal heat pumps, these stable temperatures
(55-60° F) can be tapped, and used in heating and cooling applications.
In heating mode, heat is extracted from the earth by the geothermal
heat pump and distributed to the home or building—typically
through a system of air ducts. Cooler air from the building is returned
into the ground to be reheated. In cooling mode, the process is
reversed.
Producing
Electricity
In some
regions, including the United States’ West Coast and the West
Coast of South America, underground temperatures are much higher
because magma
or molten rock is much closer to the earth’s surface. These
regions can use the extreme temperatures to actually generate electricity.
 To
produce electric power from geothermal resources, underground reservoirs
of steam or hot water are tapped by wells, and this steam is used
to rotate turbines that generate electricity. Typically, water is
returned to the ground to recharge the reservoir and reheat, completing
the renewable energy cycle.
In some areas,
water is already in steam form when it’s extracted through
the wells. The world’s largest geothermal area is called "The
Geysers",
an area north of Napa Valley, California. Steam wells fuel twenty-one
separate electric plants in this region, pumping out a total of
1000 MW
of electricity.
Benefits
Electrical
Generation
However geothermal is
used, there are many benefits. Geothermal produces no emissions.
The resource is naturally renewable. Using this resource can help
reduce the demand for fossil fuels – the only outside energy
source you would need for heating/cooling air is for energy to run
the heat pumps.
Limitations
 The
biggest limitations of using geothermal to generate electricity
is related to geography and geology – there are relatively
few places on earth that have magma close enough to the earth’s
crust to create the conditions necessary for generating electricity
in an economical way. These locations are in regions where there
are young volcanoes, crustal shifts, and recent mountain building.
See a clickable
map of geothermal hotspots at the Geothermal
Education Office site.
 Cost
is another limitation. Like some other types of electrical generation,
the costs of drilling the wells and building the plants can be very
expensive. Once all that initial money is spent, the cost of producing
geothermal electricity is quite competitive with other forms of
electrical generation. A geothermal heating/cooling system is more
expensive to install than other systems. Over time though, experts
say the savings in heating and cooling costs more than pay for the
system. People who live in extreme climates can see the return on
their investment within three to five years.
 Check
it out!
The
thermal energy in the uppermost six miles of the earth’s
crust amounts to 50,000 times the energy of all the oil
and gas resources in the world.
The
first experimental generation of electricity from natural
steam happened at Laderello, Italy, in 1904. In 1913, a
250 kW
generating station started generating electricity. It is
still producing electricity today.
The
Science
Geek at ABC News online answers questions about geothermal
power.
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Sources
- Electric
Power Research Institute. (Online)
HTTP://www.epri.com. June 2001.
- Geothermal
Education Office. "Geothermal Facts."
http://geothermal.marin.org/GEOpresentation/sld067.htm.
June 2001.
- National
Renewable Energy Laboratory (NREL). "Geothermal Energy." (Online)
HTTP://www.nrel.gov/documents/geothermal_energy.html.
June 2001.
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Places
Around the World that Use Geothermal Energy
 Iceland’s
capital city of Reykjavik (rayk-yah-vick) gets 90 % of its heat
for homes and public buildings by directing hot water from the earth
into a system of pipes under the streets. More
Geothermal
Iowa
 Geothermal
heating reduces noise, is a cleaner energy source, and is easier
to maintain than the old system. More
Web
Links
Where in the
world is geothermal energy being used? Find
out.
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