Geothermal energy

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Krafla Geothermal Station in northeast Iceland
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Renewable energy

Geothermal power (from the Greek words geo, meaning earth, and therme, meaning heat) is energy generated by heat stored beneath the Earth's surface or the collection of absorbed heat in the atmosphere and oceans. Prince Piero Ginori Conti tested the first geothermal generator on 4 July 1904, at the Larderello dry steam field in Italy.[1] The largest group of geothermal power plants in the world is located in The Geysers, a geothermal field in California.[2] As of 2007, geothermal power supplies less than 1% of the world's energy.[3]

Advantages

The Nesjavellir Geothermal Power Plant in Iceland

Geothermal energy offers a number of advantages over traditional fossil fuel based sources. From an environmental standpoint, the energy harnessed is clean and safe for the surrounding environment.[4] It is also sustainable because the hot water used in the geothermal process can be re-injected into the ground to produce more steam. In addition, geothermal power plants are unaffected by changing weather conditions.[5] Geothermal power plants work continuously, day and night, making them base load power plants. From an economic view, geothermal energy is extremely price competitive in some areas and reduces reliance on fossil fuels and their inherent price unpredictability.[6] It also offers a degree of scalability: a large geothermal plant can power entire cities while smaller power plants can supply more remote sites such as rural villages.[7]

Disadvantages

There are several environmental concerns behind geothermal energy. Construction of the power plants can adversely affect land stability in the surrounding region. This is mainly a concern with Enhanced Geothermal Systems, where water is injected into hot dry rock where no water was before.[8] Dry steam and flash steam power plants also emit low levels of carbon dioxide, nitric oxide, and sulfur, although at roughly 5% of the levels emitted by fossil fuel power plants.[7] However, geothermal plants can be built with emissions-controlling systems that can inject these gases back into the earth, thereby reducing carbon emissions to less than 0.1% of those from fossil fuel power plants.[9]

Although geothermal sites are capable of providing heat for many decades, eventually specific locations may cool down. It is likely that in these locations, the system was designed too large for the site, since there is only so much energy that can be stored and replenished in a given volume of earth. Some interpret this as meaning a specific geothermal location can undergo depletion, and question whether geothermal energy is truly renewable, but if left alone, these places will recover some of their lost heat, as the mantle has vast heat reserves. An assessment of the total potential for electricity production from the high-temperature geothermal fields in Iceland gives a value of about 1500 TWh or 15 TWh per year over a 100 year period. The electricity production capacity from geothermal fields is now only 1.3 TWh per year. [10]

Potential

If heat recovered by ground source heat pumps is included, the non-electric generating capacity of geothermal energy is estimated at more than 100 GW (gigawatts of thermal power) and is used commercially in over 70 countries.[4] During 2005, contracts were placed for an additional 0.5 GW of capacity in the United States, while there were also plants under construction in 11 other countries.[11]

Estimates of exploitable worldwide geothermal energy resources vary considerably. According to a 1999 study, it was thought that this might amount to between 65 and 138 GW of electrical generation capacity 'using enhanced technology'.[12]

A 2006 report by MIT, that took into account the use of Enhanced Geothermal Systems (EGS), concluded that it would be affordable to generate 100 GWe (gigawatts of electricity) or more by 2050 in the United States alone, for a maximum investment of 1 billion US dollars in research and development over 15 years.[11]

The MIT report calculated the world's total EGS resources to be over 13,000 ZJ. Of these, over 200 ZJ would be extractable, with the potential to increase this to over 2,000 ZJ with technology improvements - sufficient to provide all the world's energy needs for several millennia.[11]

The key characteristic of an EGS (also called a Hot Dry Rock system), is that it reaches at least 10 km down into hard rock. At a typical site two holes would be bored and the deep rock between them fractured. Water would be pumped down one and steam would come up the other. The MIT report estimated that there was enough energy in hard rocks 10 km below the United States to supply all the world's current needs for 30,000 years. [11]

Drilling at this depth is now routine for the oil industry (Exxon announced an 11 km hole at the Chayvo field, Sakhalin. Lloyds List 1/5/07 p 6). The technological challenges are to drill wider bores and to break rock over larger volumes. Apart from the energy used to make the bores, the process releases no greenhouse gases.

Other important countries are China, Hungary, Mexico, Iceland, and New Zealand. There are a number of potential sites being developed or evaluated in South Australia that are several kilometres in depth.

History of development

Geothermal steam and hot springs have been used for centuries for bathing and heating, but it wasn't until the 20th century that geothermal power started being used to make electricity.

Prince Piero Ginori Conti tested the first geothermal power generator on 4 July 1904, at the Larderello dry steam field in Italy. It was a small generator that lit four light bulbs.[13] Later, in 1911, the world's first geothermal power plant was built there. It was the world's only industrial producer of geothermal electricity until 1958, when New Zealand built a plant of its own.

The first Geothermal power plant in the United States was made in 1922 by John D. Grant at The Geysers Resort Hotel. After drilling for more steam, he was able to generate enough electricity to light the entire resort. Eventually the power plant fell into disuse, as it was not competitive with other methods of energy production.[14]

In 1960, Pacific Gas and Electric began operation of the first successful geothermal power plant in the United States at The Geysers. The original turbine installed lasted for more than 30 years and produced 11 MW net power. The Geysers are currently owned by the Calpine corporation and the Northern California Power agency; and it currently produces over 750 MW of power. [14]

Development around the world

Geothermal power is generated in over 20 countries around the world including Iceland, the United States, Italy, Germany, France, Samogitia (Lithuania), New Zealand, Mexico, Nicaragua, Costa Rica, Russia, the Philippines, Indonesia, the People's Republic of China, Japan and Saint Kitts and Nevis. Chevron Corporation is the world's largest producer of geothermal energy. Canada's government (which officially notes some 30,000 earth-heat installations for providing space heating to Canadian residential and commercial buildings) reports a test geothermal-electrical site in the Meager Mountain-Pebble Creek area of British Columbia, where a 100 MW facility could be developed.

Africa

Geothermal power is very cost-effective in the Rift area of Africa. Kenya was the first African country to build geothermal energy sources. Kenya's KenGen has built two plants, Olkaria I (45 MW) and Olkaria II (65 MW), with a third private plant Olkaria III (48 MW). Plans are to increase production capacity by another 576 MW by 2017, covering 25% of Kenya's electricity needs, and correspondingly reducing dependency on imported oil. Hot spots have been found across the continent, especially in the Great Rift Valley.

Australia

Main article: Geothermal energy exploration in Central Australia

Iceland

Main article: Geothermal power in Iceland

Iceland is situated in an area with a high concentration of volcanoes, making it an ideal location for generating geothermal energy. 19.1% of Iceland's electrical energy is generated from geothermal sources[15]. In addition, geothermal heating is used to heat 87% of homes in Iceland. Icelanders plan to be 100% non-fossil fuel in the near future.[16]

Mexico

Mexico has the third greatest geothermal energy production with an installed capacity of 959.50 MW by December 2007, this represents 3.24% of its total electricity generated.[17][18][19]

New Zealand

New Zealand has operated geothermal power stations since the 1950s. Frist developements were at Wairakei and Kawerau (durect heat and power). Other stations are Ohaaki,Rotokawa,Poihipi, Nagwha and Mokai.

See: Kawerau geothermal power station
See: Wairakei geothermal power

Geothermal power plant in Valencia, Negros Oriental, Philippines

New Zealand geothermal feilds [2]

North Dominica

North Dominica recently installed a geothermal power plant near the city of Opravy.

Portugal

Portugal has a geothermal power plant on São Miguel Island, in the Azores islands.

Philippines

The US Geothermal Education Office and a 1980 article entitled "The Philippines geothermal success story" by Rudolph J. Birsic published in the journal Geothermal Energy (vol. 8, Aug.-Sept. 1980, p. 35-44) note the remarkable geothermal resources of the Philippines. [20][21] During the World Geothermal Congress 2000 held in Beppu, Ōita Prefecture of Japan (May-June 2000), it was reported that the Philippines is the largest consumer of electricity from geothermal sources and highlighted the potential role of geothermal energy in providing energy needs for developing countries.[22]

According to the International Geothermal Association (IGA), worldwide, the Philippines ranks second to the United States in producing geothermal energy. As of the end of 2003, the US has a capacity of 2020 megawatts of geothermal power, while the Philippines can generate 1930 megawatts. (Mexico is third with 953 MW according to IGA). [23] Early statistics from the Institute for Green Resources and Environment stated that Philippine geothermal energy provides 16% of the country's electricity.[24] By 2005, geothermal energy accounted for 17.5% of the country's electricity production. [25]. More recent statistics from the IGA show that combined energy from geothermal power plants in the islands of Luzon, Leyte, Negros and Mindanao account for approximately 27% of the country's electricity generation. Leyte is one of the islands in the Philippines where the first geothermal power plant started operations in July 1977.[21]

Saint Kitts and Nevis

The island of Nevis, long known for its numerous hot springs, commenced drilling for the construction of a geothermal powerplant at Spring Hill, Nevis, in January 2008. When completed (estimated 2010), the plant will supply 50 megawatts of electricity, enough to fulfill all of Nevis' demand (approximately 10 megawatts), and also enough to export to neighbouring Saint Kitts as well as other nearby islands via submarine electrical transmission cables. The project, being undertaken by West Indies Power, will make Saint Kitts and Nevis the first country in the Caribbean to utilize large-scale Geothermal energy, and, when complete, will make Saint Kitts and Nevis one of the least dependent nations in the world on fossil-fuels.[26]

United Kingdom

Main article: Geothermal power in the United Kingdom
The West Ford Flat power plant is one of 21 power plants at The Geysers

United States

Main article: Geothermal energy in the United States

The United States of America is the country with the greatest geothermal energy production.[27]

The largest dry steam field in the world is The Geysers, 72 miles (116 km) north of San Francisco. The Geysers began in 1960, has 1360 MW of installed capacity and produces over 750 MW net. Calpine Corporation now owns 19 of the 21 plants in The Geysers and is currently the United States' largest producer of renewable geothermal energy. The other two plants are owned jointly by the Northern California Power Agency and the City of Santa Clara's municipal Electric Utility (now called Silicon Valley Power). Since the activities of one geothermal plant affects those nearby, the consolidation plant ownership at The Geysers has been beneficial because the plants operate cooperatively instead of in their own short-term interest. The Geysers is now recharged by injecting treated sewage effluent from the City of Santa Rosa and the Lake County sewage treatment plant. This sewage effluent used to be dumped into rivers and streams and is now piped to the geothermal field where it replenishes the steam produced for power generation.

Another major geothermal area is located in south central California, on the southeast side of the Salton Sea, near the cities of Niland and Calipatria, California. As of 2001, there were 15 geothermal plants producing electricity in the area. CalEnergy owns about half of them and the rest are owned by various companies. Combined the plants have a capacity of about 570 megawatts.

The Basin and Range geologic province in Nevada, southeastern Oregon, southwestern Idaho, Arizona and western Utah is now an area of rapid geothermal development. Several small power plants were built during the late 1980s during times of high power prices. Rising energy costs have spurred new development. Plants in Nevada at Steamboat near Reno, Brady/Desert Peak, Dixie Valley, Soda Lake, Stillwater and Beowawe now produce about 235 MW.

See also

Look up geothermal in Wiktionary, the free dictionary.

References

  1. ^ THE CELEBRATION OF THE CENTENARY OF THE GEOTHERMAL-ELECTRIC INDUSTRY WAS CONCLUDED IN FLORENCE ON DECEMBER 10th, 2005 in IGA News #64, April - June 2006. Publication of UGI/Italian Geothermal Union.
  2. ^ [1] Calpine Corporation page on The Geysers
  3. ^ January 2007 IEA Fact sheet: "Renewables in Global Energy Supply"
  4. ^ Geothermal Energy
  5. ^ Kenya Looks Underground for Power
  6. ^ Overview, U.S. Department of Energy
  7. ^ a b Geothermal Energy
  8. ^ Engeler, Eliane; Higgins, Alexander G. (2007-08-06). "Energy search goes underground". Yahoo! News. Associated Press. Retrieved 2007-09-11.
  9. ^ Golob, Richard & Brus, Eric. (1993) The Almanac of Renewable Energy. New York: Henry Holt & Co. ISBN 0-8050-1948-0
  10. ^ Sverrisdottir, Valgerdur. Energy in Iceland: The Resource, its Utilisation and the Energy Policy. Presentation at the Iceland National Hydrogen Association's 11th Annual U.S. Hydrogen Meeting and Exposition, 1 March 2000. Retrieved on 31 October 2007
  11. ^ a b c d The Future of Geothermal Energy, Idaho National Laboratory
  12. ^ "Geothermal Energy Association - Washington, DC" (http). Retrieved 2007-02-07.
  13. ^ Tiwari, G. N.; Ghosal, M. K. Renewable Energy Resources: Basic Principles and Applications. Alpha Science Int'l Ltd., 2005 ISBN 1842651250
  14. ^ a b "A History of Geothermal Energy in the United States". U.S. Department of Energy, Geothermal Technologies Program. Retrieved 2007-09-10.
  15. ^ "International Energy Agency, Energy Statistic - Electricity/Heat in Iceland in 2005". Retrieved 2007-04-24.
  16. ^ "Energy Statistics in Iceland" (PDF). Orkustofnun (Iceland Energy Authority). Retrieved 2006-09-20.
  17. ^ Federal Comission of Electricity of Mexico/Geothermal-electric production 2007
  18. ^ Main aspects of geothermal energy in Mexico
  19. ^ IGA electricity generation for Mexico
  20. ^ Geothermal Education Office - The Philippines
  21. ^ a b Birsic, R.J. The Philippines geothermal success story Geothermal Energy (vol. 8, Aug.-Sept. 1980, p. 35-44)
  22. ^ World Geothermal Congress 2000
  23. ^ IGA electricity generation for Mexico
  24. ^ Institute for Green Resources and Environment: Asian Geothermal Symposium
  25. ^ "International Energy Agency, Energy Statistic - Electricity/Heat in Philippines in 2005". Retrieved 2007-04-24.
  26. ^ Geothermal Development Drilling Begins on Nevis
  27. ^ "All About Geothermal Energy - Current Use". Geothermal Energy Association. Retrieved 2007-01-25.

External links

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