Geothermal
energy has been used throughout the world for thousands of years. Hot
springs were used by the both the Romans and the Native Americans. In
1904, the first geothermal power plant was built in Larderello, Italy.
This plant powered five light bulbs, demonstrating that geothermal power
was possible. In 1960, the Geysers in California were developed to generate
electricity. Another wave of geothermal development occurred in the
1980s, fueled by high electricity costs, and expensive fossil fuels.
With today’s concern about energy, there is a renewed interest
in geothermal power.
Geothermal energy is literally “heat from the ground.” The
deeper one goes beneath the earth’s surface, the hotter it becomes.
When water from the earth’s surface seeps into the earth, it absorbs
the heat of the ground around it. This forms a geothermal reservoir.
If the reservoir source is very hot (200C+) flash technology is used.
When water is under very high pressure, the boiling temperature rises.
When pumped to the surface where the pressure is lower, the superheated
water boils and turns into steam, which is used to drive a turbine.
For lower temperature geothermal sources, there is not enough energy
in the steam to effectively drive a turbine. For these lower temperature
resources, binary systems are used to extract the energy and convert
it to electricity. A binary system uses a secondary fluid that boils
at a lower temperature. The process is similar to running a refrigerator
in reverse. The geothermal water is run through a heat exchanger with
the secondary fluid. The secondary fluid vaporizes when heated, and
this vapor drives the turbine. The vapor condenses and the secondary
fluid is circulated back into the heat exchanger, repeating the process.
The first geothermal power plant was started in 1904 in Larderello,
Italy. It is still in operation today. Geothermal energy can be used
to provide both electricity and heat.
Geothermal energy is reliable, clean, and renewable.
When compared to other types of power plants, geothermal power plants
have a very small footprint on the local area in which they are situated.
Geothermal electricity plants provide a steady source of power, operating
more than 95% of the year.
Iceland generates 17% of its electricity, and 87% of its heating from
geothermal energy.
Geothermal energy is used in more than 20 countries to generate electricity,
including Iceland, USA, Japan, Italy, Indonesia, New Zealand, Mexico,
the Philippines, Kenya, Costa Rica, and Nicaragua.
BACK TO TOP
