John W. Lund

WORLD-WIDE DIRECT USES OF GEOTHERMAL ENERGY 2000

Abstract The worldwide application of geothermal energy for direct utilization is reviewed. This paper attempts to update the previous survey carried out in 1995 (Freeston, 1995) and presented at the World Geothermal Congress 1995 in Florence, Italy. For each of these updates since 1975, the recording of data has been similar, but not exactly the same. As in 1995, an effort was made to quantify geothermal heat pump data and the investment in geothermal energy development. Final update papers were received from 60 countries, of which 55 reported some form of geothermal direct utilization. Three additional countries were added to the list based on other sources of information. An estimate of the installed thermal power at the beginning of 2000 (1995 values in brackets) from the current reports is 15,145 MWt [8664 MWt] utilizing at least 52,746 kg/s [37,050 kg/s] of fluid, and the thermal energy used is 190,699 TJ/yr [112,441 TJ/yr]. The distribution of the thermal energy used by category is approximately 42% for bathing and swimming pool heating, 23% for space heating, 12% for geothermal heat pumps, 9% for greenhouse heating, 6% for aquaculture pond and raceway heating, 5% for industrial applications, 2% for other uses, and less than 1% each for agricultural drying, snow melting, and air conditioning. The reported data for number of wells drilled was 1028, the work by professionals over the five-year period was 3363 person-years, and the total investment over the same five years was 841 million US

Direct heat utilization of geothermal resources

, indicating minimum values.

Direct-use of geothermal energy in the USA

Direct utilization of geothermal energy consists of various forms for heating and cooling instead of converting the energy for electric power generation. The major areas of direct utilization are (1) swimming, bathing and balneology, (2) space heating and cooling including district heating, (3) agriculture applications, (4) aquaculture applications, (5) industrial processes, and (6) heat pumps. Major direct utilization projects exploiting geothermal energy exist in about 38 countries, and the estimated installed thermal power is almost 9,000 MWt utilizing 37,000 kg/s of fluid. The world-wide thermal energy used is estimated to be at least 108,100 TJ/yr (30,000 GWh/yr) - saving 3.65 million TOE/yr. The majority of this energy use is for space heating (33%), and swimming and bathing (19%). In the USA the installed thermal power is 1874 MWt, and the annual energy use is 13,890 TJ (3,860 GWh). The majority of the use (59 %) is for heat pumps (both ground coupled and water source), with space heating, bathing and swimming, and fish and animal farming each supplying about 10%.

The USA geothermal country update

The direct utilization of geothermal energy in the United States includes the heating of pools and spas, greenhouses and aquaculture facilities, space heating and district heating, snow melting, agricultural drying, industrial applications and ground-source heat pumps. The installed capacity is 4200 MWt and the annual energy use is 21,700 TJ (6040 GWh). The largest application is ground-source (geothermal) heat pumps (59% of the energy use), and the largest direct-use for is in aquaculture. Direct utilization is increasing at about eight percent per year. A US Department of Energy program, GeoPowering the West, has been formulated to expand the production and use of geothermal electricity and heat in the western United States.

Development and Utilization of Geothermal Resources

Geothermal energy is used for electric power generation and direct utilization in the United States. The present installed capacity (gross) for electric power generation is about 2020 MWe, with 1902 MWe net delivering power to the grid, producing approximately 16,000 GWh per year for a 96% capacity factor. Geothermal electric power plants are located in California, Nevada, Utah and Hawaii. The two largest concentrations of plants are at The Geysers in northern California and the Imperial Valley in southern California. The latest development at The Geysers, due to recent declines in steam output, is the injection of recycled wastewater from two communities into the reservoir, which has at present permitted the recovery of 70 MWe of power generation. The direct utilization of geothermal energy includes the heating of pools and spas, greenhouses and aquaculture facilities, space heating and district heating, snow melting, agricultural drying, industrial applications and ground-source heat pumps. The installed capacity is about 4350 MWt and the annual energy use is 22,250 TJ, or 6181 GWh. The largest application is that of ground-source (geothermal) heat pumps (60% of the energy use), and the largest direct-use is that of aquaculture pond and raceway water heating. Direct utilization is increasing at about 6% per year, whereas electric power plant development is almost static. The energy savings from electric power generation, direct uses and ground-source heat pumps amount to 6.6 million tonnes of equivalent fuel oil per year and represents a reduction in air pollution of 5.8 million tonnes of carbon annually (compared to fuel oil).

Balneological use of thermal and mineral waters in the U.S.A.

Geothermal energy has been used for centuries for bathing, cooking and space heating. More recently district heating and industrial processing along with geothermal heat pumps has become part of the direct-use mix. Geothermal electric power generation was started in Italy in 1904, with the first commercial plant on line in 1913. In 2005 the total installed capacity for direct use was 28,268 MWt producing 75,943 GWh/yr in 72 countries. Also the installed capacity for electric power was 8,933 MWe generating 56,786 GWh/yr in 24 countries. Energy savings amount to an equivalent 270 million barrels (41 million tonnes) of fuel oil. Since, geothermal energy is widespread and often located in remote areas; it is often used as distributed energy, providing a local and domestic source of renewable energy. This distributed use contributes to the energy security of the country.

Geothermal Direct Use

Abstract In the United States, natural springs, especially geothermal ones, have gone through three stages of development: (1) use by Indians as a sacred place, (2) development by the early European settlers to emulate the spas of Europe, and (3) finally, as a place of relaxation and fitness. The main reasons that people in the U.S.A. visit geothermal spas today are to improve their health and appearance, to escape stress, and to refresh and revitalize their bodies and minds. Unlike European spas, where medical cures of specific ailments are more important, U.S. spas place more emphasis on exercise, on reducing stress, on lifting depression, and on losing weight. Soaking in hot tubs and pools, as well as in natural primitive hot springs, is a favorite pastime. There are over 115 major geothermal spas in the U.S.A., and many more smaller ones, along with thousands of hot springs. The majority of these are located in the volcanic regions of the western states, but several famous ones still exist in the east. The major spas are estimated to have an annual energy use of 1.53 × 1012 kJ (46 × 103 TOE). Most of the geothermal heat is used in bathing, and very little for space heating.

Geothermal heating of greenhouses and aquaculture facilties

Direct or nonelectric utilization of geothermal energy refers to the immediate use of the heat energy rather than to its conversion to some other form such as electrical energy. The primary forms of direct heat use are for swimming, bathing, and balneology (therapeutic use); space heating and cooling, including district heating; agriculture (mainly greenhouse heating and some animal husbandry), aquaculture (mainly fish pond and raceway heating), and industrial processes; and heat pumps (for both heating and cooling). In general, the geothermal fluid temperatures required for direct heat use are lower than those for economic electric power generation.

Agriculture and aquaculture applications of geothermal energy

There are at least 44 greenhouse and 60 aquaculture sites using geothermal energy in the United States. The installed capacity is 93 and 140 MWt respectively. The annual energy use is 724 and 2,729 TJ (201 and 833 GWh/yr) respectively. Aquaculture has the largest use of geothermal energy in the U.S. at 33%, and greenhouses amounts to slightly over 8.5% of the total energy use, if geothermal heat pumps are not considered. The Geo-Heat Center in Klamath Falls has a technical assistance program to provide advice and preliminary engineering and economic analysis of projects for potential greenhouse and aquaculture developers. In response to numerous requests for information from prospective developers of greenhouse and aquaculture projects using geothermal energy, we prepared two comprehensive documents to assist these developers (Boyd and Rafferty 1997a; Boyd and Rafferty, 2006b). The documents have been updated this year and the contents of these are outlined below.

U.S.A. experience in direct heat use

Abstract Agriculture and aquaculture applications are particularly attractive for geothermal applications because they require heating at the lower end of the temperature range where there is an abundance of geothermal resources. Use of waste heat or the cascading of geothermal energy from power plants or other high-temperature uses also have excellent possibilities. A number of agribusiness applications can be considered such as greenhouses, aquaculture, animal husbandry, soil warming and irrigation, mushroom raising and biogas generation.