The development of geothermal electricity:

Geothermal energy can be used directly for heating purposes, or it can be converted into electricity.

For heating buildings

Hydrothermal resources of low to moderate temperature (20 to 150 degrees Celsius) are utilised to provide direct heating for a range of applications in the residential, commercial and industrial sectors. These applications include space heating, water heating, greenhouse heating, heating for aquaculture, food dehydration, laundries, and textile processes. Such applications are common in Iceland, the United States, Japan and France, as well as in many other countries. Professor Carl Nielsen at Ohio State University invented the first geothermal heating system in 1948. In Iceland, most of the residential houses are heated by geothermal district heating systems.

Above - Prince Piero Ginori Conti established the world's first geothermal power station with a 10kW generator.

Direct-use geothermal systems usually consist of a production facility (e.g. a well) to convey the heated water to the surface, a mechanical system (e.g. piping, a heat exchanger, pump, controls) to convey the heat energy to where it is required, and a disposal system (e.g. injection well or storage pond) to receive the cooled fluid. Heat exchangers are generally required due to the salt and solids content of the geothermal fluid.

For more information, go to:
http://www.nrel.gov/docs/fy04osti/36316.pdf

Heat pumps are often used to deliver the heat energy. Geothermal heat pumps are devices which operate on the same principle as the refrigerator, but can move heat in either direction. The devices can therefore take advantage of the relatively constant temperature of the earth's interior for both heating and cooling. In summer, heat is extracted from a building and dissipated into the earth. In winter, heat is removed from the earth and pumped into the building. Such systems are used widely in Switzerland and the Scandinavian countries. Through the use of geothermal heat pumps, marginal geothermal resources with temperatures as low as 20 degrees Celsius can be utilised.

For more information about heat pumps, go to:
http://www.eere.energy.gov

The direct use of geothermal resources is a proven, mature technology and is commercially viable for many applications. The use of this resource can result in a net saving in energy costs for consumers in homes and commercial operations.

For electricity generation

High temperature geothermal resources can be used for electricity production. The first attempt to convert geothermal energy into electricity was conducted in Larderello, Italy, in 1904. The first geothermal power plant was opened in California in 1921. In many parts of the world, geothermal electricity is competitive with conventional energy sources. By the end of 2003, the installed generating capacity of geothermal power plants had grown to 8,402MW e in 25 countries . At this time, the countries with the most installed generating capacity included USA, the Philippines, Indonesia and Mexico but geothermal energy is also being used in many other countries.

For more information about the world’s geothermal electricity generation, go to:
http://iga.igg.cnr.it/geoworld/geoworld.php?sub=elgen

^ back to top ^