Geothermal power generation capacity worldwide rose from 7,972.7 MW in 2000 to 8,933 MW in 2005, with 8,035 MW running. This is about 0.2% of the total world installed power generating capacity.
The geothermal heat pump (GHP), also known as the Ground-Source Heat Pump (GSHP) or generically as geoexchange, is the fastest growing geothermal application today. GSHP is a highly efficient renewable energy technology that is gaining wide acceptance for both residential and commercial buildings, with 1.4 million installations worldwide by 2005, and growth from 1,854 MWt of capacity in 1995 to 15,284 MWt in 2005.
Ground-Source Heat Pumps are used for space heating and cooling, as well as water heating. The technology relies on the fact that the Earth (beneath the surface) remains at a relatively constant temperature throughout the year, warmer than the air above it during the winter and cooler in the summer. GSHP systems do work that ordinarily requires two appliances, a furnace and an air conditioner and use 25%-50% less electricity than conventional heating or cooling systems.
Geothermal technology is suitable for integrated regional energy systems, rural electrification and mini-grid applications, especially in distributed generation systems, in addition to national grid applications. It is being promoted as a regional resource, combining the exploitation of renewable energy resources together with environmental advantages.
Geothermal energy is contained in the heated rocks and fluid that fill the fractures and pores within the earth’s crust. It can be harvested in two ways, direct use of hot water or steam for space heating or industrial use such as aquaculture, thermal baths and hot springs, and to power electricity generation plants. Direct use is confined to low temperatures, usually below 150o C whereas, power generation employs high temperature resources over 150o C. 80 countries have developed direct use of geothermal energy and 20 exploit geothermal energy for power generation. Direct low-temperature use employs about twice the energy capacity as is used for power generation.
Direct use of geothermal heat has been used for thousands of years. The major direct use applications today are GSHP installations for space heating, presently estimated to exceed 500,000 and are the first in terms of global capacity but third in terms of output. Direct use of geothermal energy achieves 50-70% efficiency, compared with the 5-20% efficiency achieved with the indirect use of generating electricity.
Geothermal power started in 1904 with the Larderello field in Tuscany, which produced the world’s first geothermal electricity. Major production at Larderello began in the 1930s and by 1970; power capacity had reached 350 MW. The Geysers in California started in the 1960s is the largest geothermal plant in the world. Individual geothermal power plants can be as small as 100 kW or as large as 100 MW depending on the energy resource and power demand.
The three countries with the largest amount of installed direct heat use capacity are USA (5,366 MW), China (2,814 MW) and Iceland (1,469 MW), accounting for 58% of world capacity, which has reached 16,649 MW.
The global installed capacity of geothermal power generation at in December 2005 was 8,933 MW, of which 8,035 MW was operational. Six countries accounted for 86% of the geothermal generation capacity in the world. The USA is first with 2,564 MW (1,935 MW operational), followed by Philippines (1,931 MW, 1,838 MW operational); four countries (Mexico, Italy, Indonesia, Japan) had capacity at the end of 2005 in the range of 535-953 MW each. Mexico and Indonesia have grown 26% and 35% respectively between 2000 and 2005. Although on a smaller base, Kenya achieved the highest growth, from 45 MW to 129 MW.
In the last five years geothermal power generation has grown at an annual rate of 2.3% globally, a slower pace than the 3.25 in the previous five years, while direct heat use showed a strong increase. With current technology, the global potential capacity for geothermal generation is estimated at 72,500 MW and at 138,100 MW with enhanced technology.
A strong decline in the USA in recent years, due to over-exploitation of the Geysers steam field, has been partly compensated by important additions to capacity in several countries: Mexico, Indonesia, Philippines, Italy, New Zealand, Iceland, Mexico, Costa Rica, El Salvador and Kenya. Newcomers in the electric power sector are Ethiopia (1998), Guatemala (1998), Austria (2001) and Nicaragua.
In 2005 and 2006 the United States showed strong signs of renewed growth for geothermal power generation. Five states now have geothermal power generating facilities; California, Nevada, Utah, Alaska and Hawaii. The Richard Burdett Power Plant (formerly Galena I) in Nevada commenced generating power in 2005 and the first geothermal power plant in Alaska being installed in 2006 at Chena Hot Springs. A fairly extensive list of projects has been
announced for the next ten years, with new installations planned in Arizona, Idaho, New Mexico and Oregon, in addition to the existing five ‘geothermal’ states. Japan, Philippines and Nicaragua have all announced ambitious plans for further development of geothermal power.
There are three basic technologies for generating electricity from geothermal energy. Dry steam power plants using dry steam systems were the first type of geothermal power generation plants to be built. They use the steam from the geothermal reservoir as it comes from wells and route it directly through turbine/generator units to produce electricity. Flash steam plants are the most common type of geothermal power generation plants in operation today. They use water at temperatures greater than 182°C that is pumped under high
pressure to the generation equipment at the surface. Upon reaching the generation equipment, the pressure is suddenly reduced, allowing some of the hot water to convert or “flash” into steam.
This steam is then used to power the turbine/generator units to produce electricity. Binary cycle geothermal power generation plants differ from dry steam and flash steam systems in that the water or steam from the geothermal reservoir never comes in contact with the turbine/generator units but is used to heat another “working fluid” which is vaporised and used to turn the turbine/generator units.
Geothermal power projects require high capital investment for exploration, drilling wells and installation of plant, but have low operating costs because of the low marginal cost of fuel. Return on investment is not achieved as quickly as with cheaper fossil fuel power plant, but longer term economic benefits accrue from the use of this indigenous fuel source.
Construction costs of geothermal plants can vary widely, depending on local conditions and range from a minimum of $1.1 million to $ 3 million per megawatt. The DOE has calculated an average cost of $1.68 million for geothermal plants built in the Northwest of America in the last two years, where the bulk of US plants are situated or planned. However, while this is high in
comparison with gas power, which can be as low as $460,000 per megawatt, the operating cost can be lower because there is no cost of fuel.
The leaders in developing geothermal technology and installing new plants are three American companies – Calpine, Unocal and Ormat, and one Japanese company- Marubeni. These companies have been active in establishing joint ventures in the Philippines and Indonesia and more recently in Central America.
In December 2005 the installed geothermal capacity in the USA was 2,564 MW, of which 1,935 MW was usable. The considerable difference between installed capacity and operating capacity in the USA was due to lack of steam caused by over-exploitation of the Geysers geothermal field in California. On this site, available steam can now only supply 888 MW out of the 1,421 MW installed capacity.
Current geothermal resources using today’s technology are estimated at 6,520 MW and at 22,000 MW with enhanced technology.
Over the last three decades, the US geothermal power-generation industry has grown to be the largest in the world, with over 2,445 MW of installed electrical capacity. Growth during the first two decades (1960-1980) was due to a single utility’s development of one dry-steam resource. After 1983, growth shifted toward independent power producers and development of waterdominated geothermal resources at several locations.
The steady growth of geothermal development in the United States from 1960 to 1979 was led by activities at The Geysers, where the field developments of the partnership of Union Oil Company of California, Magma Energy Company, and Thermal Power Company were greatly expanded toprovide steam to the Pacific Gas and Electric Company (PG&E) electrical-generation system.
This construction made The Geysers field the largest geothermal development in the world. Production from The Geysers peaked in 1988 but pressure declines in the reservoir limited any further expansion of the field. In December 2006, it was announced that the 55 MW Bottle Rock Geothermal Power Plant at The Geysers will reopen after being dormant since 1990. It will operate initially at 20 MW with plans to expand.
Geothermal well drilling has tapered off in the US since the 1980s. In California, four wells were drilled in 1996 (one at The Geysers and three at Salton Sea), nine in 1997 (four at Coso, two at The Geysers and three at Salton Sea) and seven in 1998 (three at Coso, one at The Geysers and three in the Salton Sea). In all, between 1996 and 1998, only 13 production and seven injection wells were drilled in California. The most promising new areas for geothermal
exploration are in Hawaii and the Cascade Mountains of Washington, Oregon, and northern California.
Future developments are planned, with projects being considered in some 55 stages. Not all of these will happen since some are in the pre-planning phase and others are awaiting approval. The opinion in the geothermal industry in the US is up-beat for future expansion.
The Philippines is the second largest geothermal power generating country in the world after the USA, with installed capacity of 1,930 MW at the end of 2005, of which 1,838 MW was operational.
The Philippines now leads the world in terms of wet steam field capacity and ranks just behind the US in terms of geothermal power generation.
The Philippines is located in the Pacific Rim of Fire, a volcanic region which extends in a crescent from Sumatra in Indonesia at the western end, across the 3,000 mile archipelago of Indonesia, through the Philippines archipelago to Japan in the east. It has a considerable number of high quality geothermal resources. These are all island arc volcanic systems as typically found in the Circum-Pacific region, and show close similarities with geothermal systems in Indonesia and Japan. The widely distributed nature of the geothermal resources in the Philippines has long been an impediment to geothermal power development.
With over 20 years of experience in geothermal development and power generation, the geothermal industry in the Philippines is now in a mature state and currently the Philippines Department of Energy is supervising the operations of nine geothermal service contract areas. In the early 1990s, there was a rapid upswing in geothermal power development and 1,000 MW of geothermal capacity was added between 1993 and 1997. This was largely due to BOT
legislation in the Philippines, which allowed international power utilities to enter the market and to fund and construct geothermal power plants. This enabled an increase in the much needed generating capacity without increasing national debt.
The Philippine government plans to add 526 MW of new capacity between 2002 and 2008.
Development of geothermal potential has proceeded very slowly in Indonesia and is currently facing difficult challenges and uncertainty. Over a span of 20 years, Indonesia has developed only 797 MW of geothermal power, approximately 4% of 20,000 MW geothermal potential. In the early 1990s, eleven contracts for development of geothermal power plants were awarded, with a total committed capacity of 3,417 MW and original completion dates between 1998 and 2002. As a result of the 1997-1998 financial crisis, which brought PLN, the state utility to technical bankruptcy, the Government suspended nine conventionally powered IPPs and seven geothermal projects. The government is now attempting to resuscitate the seven contracts but
with little progress.
The new oil and gas law, passed in October 2001, bars geothermal as an area of regulation, requiring the Indonesian Government to develop a new legislative basis quickly. PLN understands that the future of geothermal power will depend on its competitiveness against other means of electricity generation. High capital costs and the associated electricity tariff required remain core problems. In addition, unresolved decentralization issues, uncertainties in security and contracts, and the potential regulatory changes of a planned geothermal law
discourage investment in geothermal projects. In the long run, Indonesia still presents one of the world’s most attractive geothermal regions, but the Indonesian Government must develop new approaches to maximize its potential.
PLN is currently negotiating to bring down tariff rates on various geothermal ESCs, with the intent of lowering prices from US ¢ 6-8 cents/kWh agreed under Power Purchase Agreements (PPAs) to around US ¢4 cents/kWh. The original prices negotiated by the geothermal developers ranged between US ¢7.25-9.81/kWh, about double the viable rate.
Italy is one of the world’s leading countries in terms of geothermal resources. Commercial power generation from geothermal resources began in Italy in 1913 with a 250 kW unit at Larderello. Subsequently, the main emphasis has been on the production of power. Geothermal electric power generating capacity in Italy has reached 791 MW with four geothermal power plants in 2005.
The geothermal development has been almost entirely privately funded. Since 1985, $US 280 million has been spent on R&D and $US 1254 million on field development. Of these funds, 99% were obtained from private sources and only 1% was derived from public sources.
Mexico is one of the fastest growing geothermal producers in the world. Twenty-seven geothermal power plants are operating in the three Mexican fields, with total geothermal capacity of 953 MW in December 2005. There is a project to install 75 MW in 2006-2008 in the new area La Primavera pending resolution of some environmental matters. CFE has programmed to increase capacity in Cerro Prieto (100 MW) and Los Humeros (25 MW) in 2010.
Direct uses of geothermal heat are widespread in Mexico, including industrial laundries, refrigeration, district and greenhouse heating, and fruit and wood drying.
The first experimental geothermal power generation in Japan took place in 1925 in Beppu and capacity reached 535 MW in December 2005, which ranks Japan sixth in the world. The government target for the year 2010 is installed geothermal capacity of 2,800MW. The plants range in size from the 65 MW Yanaizu-Nishiyama unit to the 100 kW Kirishima International Hotel back- pressure generator in Beppu, Kyushu.
The Japanese government gives substantial support to the development of geothermal power. ANRE, the Agency for Natural Resources and Energy is playing a core role in development and utilisation of geothermal energy in Japan, such as providing subsidy. NEDO plays a central role to support renewables and after a slow start is now promoting geothermal development as an element of the concept of regional renewable integrated self-sufficient systems. The introduction and promotion of geothermal energy as an alternative for petroleum, has been its major task.
The organisation is also encouraging international cooperation relating to geothermal engineering.
A further 16 countries have geothermal generating facilities of varying size, ranging from under 500 kW in Argentina to 435 MW in New Zealand. Many of the smaller countries have higher direct use.