Geothermal Direct-Heat Utilization

Abstract

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 60 countries, and the estimated installed thermal power is 15,145 MWt utilizing over 52,000 kg/s of fluid. The worldwide thermal energy used is estimated to be at least 190,700 TJ/yr (53,000 GWh/yr)--saving 13.5 million TOE/yr. The majority of this energy use is for space heating (37%), and swimming and bathing (22%). In the USA, the installed thermal power is 5,366 MWt, and the annual energy use is 20,300 TJ (5,640 GWh). The majority of the use (59%) is for the heat pumps (both ground coupled and water source), with bathing and swimming, and fish farming each supplying about 13%.