| Geothermal power generation capacity
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| | capacity in several countries: Mexico,
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| worldwide rose from 7,972.7 MW in 2000 to
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| | Indonesia, Philippines, Italy, New
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| 8,933 MW in 2005, with 8,035 MW running.
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| | Zealand, Iceland, Mexico, Costa Rica, El
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| This is about 0.2% of the total world
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| | Salvador and Kenya. Newcomers in the
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| installed power generating capacity.
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| | electric power sector are Ethiopia
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| The geothermal heat pump (GHP), also
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| | (1998), Guatemala (1998), Austria (2001)
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| known as the Ground-Source Heat Pump
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| | and Nicaragua.
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| (GSHP) or generically as geoexchange, is
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| | In 2005 and 2006 the United States showed
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| the fastest growing geothermal
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| | strong signs of renewed growth for
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| application today. GSHP is a highly
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| | geothermal power generation. Five states
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| efficient renewable energy technology
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| | now have geothermal power generating
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| that is gaining wide acceptance for both
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| | facilities; California, Nevada, Utah,
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| residential and commercial buildings,
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| | Alaska and Hawaii. The Richard Burdett
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| with 1.4 million installations worldwide
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| | Power Plant (formerly Galena I) in Nevada
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| by 2005, and growth from 1,854 MWt of
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| | commenced generating power in 2005 and
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| capacity in 1995 to 15,284 MWt in 2005.
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| | the first geothermal power plant in
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| Ground-Source Heat Pumps are used for
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| | Alaska being installed in 2006 at Chena
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| space heating and cooling, as well as
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| | Hot Springs. A fairly extensive list of
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| water heating. The technology relies on
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| | projects has beenannounced for the next
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| the fact that the Earth (beneath the
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| | ten years, with new installations planned
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| surface) remains at a relatively constant
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| | in Arizona, Idaho, New Mexico and Oregon,
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| temperature throughout the year, warmer
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| | in addition to the existing five
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| than the air above it during the winter
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| | 'geothermal' states. Japan, Philippines
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| and cooler in the summer. GSHP systems do
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| | and Nicaragua have all announced
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| work that ordinarily requires two
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| | ambitious plans for further development
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| appliances, a furnace and an air
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| | of geothermal power.
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| conditioner and use 25%-50% less
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| | There are three basic technologies for
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| electricity than conventional heating or
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| | generating electricity from geothermal
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| cooling systems.
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| | energy. Dry steam power plants using dry
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| Geothermal technology is suitable for
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| | steam systems were the first type of
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| integrated regional energy systems, rural
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| | geothermal power generation plants to be
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| electrification and mini-grid
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| | built. They use the steam from the
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| applications, especially in distributed
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| | geothermal reservoir as it comes from
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| generation systems, in addition to
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| | wells and route it directly through
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| national grid applications. It is being
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| | turbine/generator units to produce
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| promoted as a regional resource,
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| | electricity. Flash steam plants are the
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| combining the exploitation of renewable
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| | most common type of geothermal power
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| energy resources together with
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| | generation plants in operation today.
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| environmental advantages.
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| | They use water at temperatures greater
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| Geothermal energy is contained in the
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| | than 182°C that is pumped under
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| heated rocks and fluid that fill the
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| | highpressure to the generation equipment
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| fractures and pores within the earth's
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| | at the surface. Upon reaching the
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| crust. It can be harvested in two ways,
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| | generation equipment, the pressure is
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| direct use of hot water or steam for
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| | suddenly reduced, allowing some of the
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| space heating or industrial use such as
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| | hot water to convert or "flash" into
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| aquaculture, thermal baths and hot
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| | steam.
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| springs, and to power electricity
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| | This steam is then used to power the
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| generation plants. Direct use is confined
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| | turbine/generator units to produce
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| to low temperatures, usually below 150o C
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| | electricity. Binary cycle geothermal
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| whereas, power generation employs high
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| | power generation plants differ from dry
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| temperature resources over 150o C. 80
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| | steam and flash steam systems in that the
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| countries have developed direct use of
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| | water or steam from the geothermal
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| geothermal energy and 20 exploit
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| | reservoir never comes in contact with the
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| geothermal energy for power generation.
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| | turbine/generator units but is used to
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| Direct low-temperature use employs about
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| | heat another "working fluid" which is
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| twice the energy capacity as is used for
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| | vaporised and used to turn the turbine
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| power generation.
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| | generator units.
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| Direct use of geothermal heat has been
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| | Geothermal power projects require high
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| used for thousands of years. The major
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| | capital investment for exploration,
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| direct use applications today are GSHP
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| | drilling wells and installation of plant,
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| installations for space heating,
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| | but have low operating costs because of
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| presently estimated to exceed 500,000 and
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| | the low marginal cost of fuel. Return on
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| are the first in terms of global capacity
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| | investment is not achieved as quickly as
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| but third in terms of output. Direct use
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| | with cheaper fossil fuel power plant, but
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| of geothermal energy achieves 50-70%
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| | longer term economic benefits accrue from
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| efficiency, compared with the 5-20%
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| | the use of this indigenous fuel source.
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| efficiency achieved with the indirect use
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| | Construction costs of geothermal plants
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| of generating electricity.
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| | can vary widely, depending on local
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| Geothermal power started in 1904 with the
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| | conditions and range from a minimum of
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| Larderello field in Tuscany, which
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| | $1.1 million to $ 3 million per megawatt.
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| produced the world's first geothermal
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| | The DOE has calculated an average cost of
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| electricity. Major production at
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| | $1.68 million for geothermal plants built
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| Larderello began in the 1930s and by
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| | in the Northwest of America in the last
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| 1970; power capacity had reached 350 MW.
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| | two years, where the bulk of US plants
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| The Geysers in California started in the
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| | are situated or planned. However, while
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| 1960s is the largest geothermal plant in
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| | this is high incomparison with gas power,
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| the world. Individual geothermal power
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| | which can be as low as $460,000 per
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| plants can be as small as 100 kW or as
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| | megawatt, the operating cost can be lower
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| large as 100 MW depending on the energy
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| | because there is no cost of fuel.
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| resource and power demand.
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| | The leaders in developing geothermal
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| The three countries with the largest
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| | technology and installing new plants are
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| amount of installed direct heat use
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| | three American companies - Calpine,
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| capacity are USA (5,366 MW), China (2,814
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| | Unocal and Ormat, and one Japanese
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| MW) and Iceland (1,469 MW), accounting
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| | company- Marubeni. These companies have
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| for 58% of world capacity, which has
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| | been active in establishing joint
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| reached 16,649 MW.
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| | ventures in the Philippines and Indonesia
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| The global installed capacity of
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| | and more recently in Central America.
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| geothermal power generation at in
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| | USA
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| December 2005 was 8,933 MW, of which
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| | In December 2005 the installed geothermal
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| 8,035 MW was operational. Six countries
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| | capacity in the USA was 2,564 MW, of
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| accounted for 86% of the geothermal
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| | which 1,935 MW was usable. The
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| generation capacity in the world. The USA
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| | considerable difference between installed
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| is first with 2,564 MW (1,935 MW
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| | capacity and operating capacity in the
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| operational), followed by Philippines
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| | USA was due to lack of steam caused by
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| (1,931 MW, 1,838 MW operational); four
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| | over-exploitation of the Geysers
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| countries (Mexico, Italy, Indonesia,
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| | geothermal field in California. On this
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| Japan) had capacity at the end of 2005 in
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| | site, available steam can now only supply
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| the range of 535-953 MW each. Mexico and
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| | 888 MW out of the 1,421 MW installed
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| Indonesia have grown 26% and 35%
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| | capacity.
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| respectively between 2000 and 2005.
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| | Current geothermal resources using
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| Although on a smaller base, Kenya
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| | today's technology are estimated at 6,520
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| achieved the highest growth, from 45 MW
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| | MW and at 22,000 MW with enhanced
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| to 129 MW.
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| | technology.
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| In the last five years geothermal power
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| | Over the last three decades, the US
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| generation has grown at an annual rate of
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| | geothermal power-generation industry has
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| 2.3% globally, a slower pace than the
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| | grown to be the largest in the world,
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| 3.25 in the previous five years, while
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| | with over 2,445 MW of installed
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| direct heat use showed a strong increase.
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| | electrical capacity. Growth during the
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| With current technology, the global
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| | first two decades (1960-1980) was due to
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| potential capacity for geothermal
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| | a single utility's development of one
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| generation is estimated at 72,500 MW and
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| | dry-steam resource. After 1983, growth
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| at 138,100 MW with enhanced technology.
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| | shifted toward independent power
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| A strong decline in the USA in recent
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| | producers and development of
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| years, due to over-exploitation of the
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| | waterdominated geothermal resources at
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| Geysers steam field, has been partly
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| | several locations.
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| compensated by important additions to
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