Wind|Solar|Nuclear|Geothermal

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.

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