IS GEOTHERMAL ENERGY?
earth's interior - like the sun - provides heat energy from nature. This
heat - geothermal energy - yields warmth and power that we can use
without polluting the environment.
heat originates from Earth's fiery consolidation of dust and gas over 4
billion years ago. At earth's core - 4,000 miles deep -
temperatures may reach over 9,000 degrees F.
WHAT DOES THE WORD "GEOTHERMAL" MEAN?
comes from the Greek words geo (earth) and therme (heat). So, geothermal
means earth heat.
DOES GEOTHERMAL HEAT GET UP TO EARTH'S SURFACE?
heat from the earth's core continuously flows outward. It transfers
(conducts) to the surrounding layer of rock, the mantle. When
temperatures and pressures become high enough, some mantle rock melts,
becoming magma. Then, because it is lighter (less dense) than the
surrounding rock, the magma rises (convects), moving slowly up
toward the earth's crust, carrying the heat from below.
the hot magma reaches all the way to the surface, where we know it as
lava. But most often the magma remains below earth's crust, heating
nearby rock and water (rainwater that has seeped deep into the earth) -
sometimes as hot as 700 degrees F. Some of this hot geothermal water
travels back up through faults and cracks and reaches the earth's
surface as hot springs or geysers, but most of it stays
deep underground, trapped in cracks and porous rock. This natural
collection of hot water is called a geothermal reservoir.
HAVE PEOPLE USED GEOTHERMAL ENERGY IN THE PAST?
earliest times, people have used geothermal water that flowed freely
from the earth's surface as hot springs. The oldest and most common use
was, of course, just relaxing in the comforting warm waters. But
eventually, this "magic water" was used (and still is) in
other creative ways. The Romans, for example, used geothermal water to
treat eye and skin disease and, at Pompeii, to heat buildings. As early
as 10,000 years ago, Native Americans used hot springs water for cooking
and medicine. For centuries the Maoris of New Zealand have cooked "geothermally,"
and, since the 1960s, France has been heating up to 200,000 homes using
DO WE USE GEOTHERMAL ENERGY TODAY?
we drill wells into the geothermal reservoirs to bring the hot water to
the surface. Geologists, geochemists, drillers and engineers do a lot of
exploring and testing to locate underground areas that contain this
geothermal water, so we'll know where to drill geothermal production
wells. Then, once the hot water and/or steam travels up the wells to the
surface, they can be used to generate electricity in geothermal power
plants or for energy saving non-electrical purposes.
IS ELECTRICITY GENERATED USING GEOTHERMAL ENERGY?
geothermal power plants steam, heat or hot water from geothermal
reservoirs provides the force that spins the turbine generators
and produces electricity. The used geothermal water is then returned
down an injection well into the reservoir to be reheated, to
maintain pressure, and to sustain the reservoir.
are three kinds of geothermal power plants. The kind we build
depends on the temperatures and pressures of a reservoir.
"dry'" steam reservoir produces steam but very little water.
The steam is piped directly into a "dry" steam power plant
to provide the force to spin the turbine generator. The largest dry
steam field in the world is The Geysers, about 90 miles north of San
Francisco. Production of electricity started at The Geysers in 1960, at
what has become the most successful alternative energy project in
reservoir that produces mostly hot water is called a "hot water
reservoir" and is used in a "flash" power plant.
Water ranging in temperature from 300 - 700 degrees F is brought up to
the surface through the production well where, upon being released from
the pressure of the deep reservoir, some of the water flashes into steam
in a 'separator.' The steam then powers the turbines.
with temperatures between 250 - 360 degrees F is not hot enough to flash
enough steam but can still be used to produce electricity in a "binary"
power plant. In a binary system the geothermal water is passed
through a heat exchanger, where its heat is transferred into a
second (binary) liquid, such as isopentane, that boils at a lower
temperature than water. When heated, the binary liquid flashes to vapor,
which, like steam, expands across and spins the turbine blades. The
vapor is then recondensed to a liquid and is reused repeatedly. In this
closed loop cycle, there are no emissions to the air.
ARE SOME OF THE ADVANTAGES OF USING
MUCH ELECTRICITY IS FROM GEOTHERMAL ENERGY?
the first geothermally-generated electricity in the world was produced
at Larderello, Italy, in 1904 the use of geothermal energy for
electricity has grown worldwide to about 7,000 megawatts in
twenty-one countries around the world. The United States alone produces
2700 megawatts of electricity from geothermal energy, electricity
comparable to burning sixty million barrels of oil each year.
ARE SOME NON-ELECTRIC WAYS WE CAN USE GEOTHERMAL ENERGY?
water is used around the world, even when it is not hot enough to
generate electricity. Anytime geothermal water or heat are used
directly, less electricity is used. Using geothermal water 'directly' conserves
energy and replaces the use of polluting energy resources with
clean ones. The main non-electric ways we use geothermal energy are
DIRECT USES and GEOTHERMAL HEAT PUMPS.
Animals have always known to burrow into the earth, where the
temperature is relatively stable compared to the air temperature, to get
shelter from winter's cold and summer's heat. People, too, have sought
relief from bad weather in earth's caves. Today, with geothermal heat
pumps (GHP's), we take advantage of this stable earth temperature -
about 45 - 58 degrees F just a few feet below the surface - to help keep
our indoor temperatures comfortable. GHP's circulate water or other
liquids through pipes buried in a continuous loop (either horizontally
or vertically) next to a building. Depending on the weather, the system
is used for heating or cooling.
Earth's heat (the difference between the earth's temperature and the
colder temperature of the air) is transferred through the buried pipes
into the circulating liquid and then transferred again into the
During hot weather, the continually circulating fluid in the pipes
'picks up' heat from the building - thus helping to cool it - and
transfers it into the earth.
use very little electricity and are very easy on the environment.
the U.S., the temperature inside over 300,000 homes, schools and offices
is kept comfortable by these energy saving systems, and hundreds of
thousands more are used worldwide. The U.S. Environmental Protection
Agency has rated GHP's as among the most efficient of heating and
PARTS OF THE WORLD HAVE GEOTHERMAL ENERGY?
geothermal heat pumps,
use can be almost world-wide. The earth's temperature a few feet
below the ground surface is relatively constant everywhere in the
world (about 45 - 58 degrees F), while the air temperature can
change from summer to winter extremes. Unlike other kinds of
geothermal heat, shallow ground temperatures are not dependent upon
tectonic plate activity or other unique geologic processes. Thus
geothermal heat pumps can be used to help heat and cool homes
MUCH GEOTHERMAL ENERGY IS THERE?
more megawatts of power than are currently being produced could be
developed from already-identified hydrothermal resources. With improvements
in technology, much more power will become available. Usable
geothermal resources will not be limited to the "shallow"
hydrothermal reservoirs at the crustal plate boundaries. Much of the
world is underlain (3-6 miles down), by hot dry rock - no water,
but lots of heat. Scientists in the U.S.A., Japan, England, France,
Germany and Belgium have experimented with piping water into this deep
hot rock to create more hydrothermal resources for use in geothermal
power plants. As drilling technology improves, allowing us to drill much
deeper, geothermal energy from hot dry rock could be available anywhere.
At such time, we will be able to tap the true potential of the enormous
heat resources of the earth's crust.
All About Us | Our Products | Our Services | Our Equipment
Our Warranty Plans | How AC Works | How Contact Us | Facts on Central Air
HVAC Terms Used | FAQ's about HVAC | Ask Charles & Bill | Service Request
Intro to Geothermal | What is Geothermal? | How we install GEO | GEO Terms Used
FAQ's about GEO | Testimonials | Click here to email us
© Copyright 2002 -
All Rights Reserved.
Site Designed By: