Geothermal Direct Use
Geothermal reservoirs of hot water, which are found a few miles or more beneath the Earth's surface, can be used to provide heat directly. This is called the direct use of geothermal energy.
Geothermal direct use has a long history, going back to when people began using hot springs for bathing, cooking food, and loosening feathers and skin from game. Today, hot springs are still used as spas. But there are now more sophisticated ways of using this geothermal resource.
In modern direct-use systems, a well is drilled into a geothermal reservoir to provide a steady stream of hot water. The water is brought up through the well, and a mechanical system—piping, a heat exchanger, and controls—delivers the heat directly for its intended use. A disposal system then either injects the cooled water underground or disposes of it on the surface.
Geothermal hot water can be used for many applications that require heat. Its current uses include heating buildings (either individually or whole towns), raising plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes, such as pasteurizing milk.