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