Characteristics and trends in geothermal development and use, 1995 to 2020

Abstract

Production of electricity using geothermal energy started in 1904 at Larderello, Italy with an experimental 10 kWe generator. This was followed by a 250 kWe commercial unit in 1913. Italy was the world's only industrial generator of geothermally fueled electricity until 1958 when New Zealand came on-line with a 11.2 MWe unit built at Wairakei. By 1967, power plants were constructed in Mexico, the United States and Russia, where the first binary cycle power plant was installed in Kamchatka. Other countries followed: by 1970, Japan, Iceland, and China. Since WWII geothermal power has grown at an average rate of 6.2% annually. Electric power from geothermal energy, originally using steam from resources above 150 °C, is now being produced from resources with temperatures as low as 90 °C using the organic Rankine cycle process in binary power units sometimes in combination with district heating projects. Geothermal energy capacity has grown to 15,950 MWe, and 95,098 GWh of electricity produced in 29 countries. These power plants operate with an average capacity factor of 73%, many of them “on-line” over 95% of the time, providing almost continuous base-load power. The geothermally fueled electricity currently being produced serves the equivalent of 63 million people throughout the world.Direct uses of geothermal energy are traditional and well established world-wide. The people of Japan have lived in harmony with the earth's heat for centuries, using it mainly for bathing. Other nations have similarly taken advantage of hot springs for bathing and agriculture/aquaculture uses. There are now many large-scale uses of geothermal energy including district heating in Iceland and China, greenhouse heating in Hungary, and process heating with steam in New Zealand. One of the main advantages of the direct use of geothermal energy is that it can use low-to-moderate resource temperatures. The other advantage is that it can be found, often at shallow depths, almost anywhere in the world. Using ground-source heat pumps extends the use of geothermal energy to temperatures as low as 10 °C. As of 2021, 88 countries have reported some direct applications of geothermal energy with at least 10 others suspected of using this resource. Thermal energy for direct use is used 58.5% for geothermal heat pumps, 18.0% for bathing and swimming, 16.0% for space heating, 3.5% for greenhouse and covered ground heating, 1.6% for industrial applications, 1.3% for aquacultural pond and raceway heating, 0.4% for agricultural drying, 0.2% for snow melting and cooling, and 0.2% for miscellaneous applications. The installed capacity and thermal energy available worldwide today are 107,727 MWt and 1,020,887 TJ/yr. (283,580 GWh/yr.), respectively.