Geothermal Water

Abstract From earliest times, hot geothermal water or geothermal springs have been used for bathing and cooking. The first technological success in using geothermal energy was in Italy in 1904 where the worlds first geothermally driven electrical plant was opened and operated. Today, applications of low‐ and moderate‐temperature (100 to 300°F) geothermal waters have expanded enormously to include heating large tracts of homes and buildings (district heating), heating greenhouses for growing vegetables and flowers, fish farming (aquaculture), drying foods and lumber, and many other uses. In the United States alone, there are 17 district heating systems, 38 greenhouse complexes, 28 fish farms, 12 industrial plants, and 218 spas that use geothermal waters to provide heat. The district heating system in Boise, Idaho, has been operating since the 1890s and continues to provide heat today. In Iceland, most of the homes and other buildings are connected to geothermal district heating systems, and in the Paris basin in France, many homes are heated by bringing geothermal water to the surface. Geothermal greenhouses are prominent in Italy and in the western United States. Worldwide, there are about 12,000 thermal megawatts of installed direct uses of geothermal fluids in nearly 30 countries, replacing the combustion of fossil fuels equivalent to burning 830 million gallons of oil or 4.4 million tons of coal per year. This illustrates the trend of countries switching to alternative energy sources such as geothermal energy. Geothermal water discharges from numerous springs located mostly in mountainous or plateau areas. The springs are connected by faults to deeply buried reservoirs that contain geothermal water, which moves upward along the fault zones to discharge at the land surface. Much geothermal water discharges as hot springs that flow steadily instead of erupting at intervals.