| Keywords |
direct-use, low enthalpy, spas, balneology, space heating, district heating, aquaculture, greenhouses, heat pumps, crop drying, industrial applications, snow melting |
| Abstract |
The worldwide application of geothermal energy for direct utilization is reviewed. This paper attempts to update the previous survey carried out in 2000, presented at the World Geothermal Congress 2000 (WGC2000) in Japan and subsequently updated (Lund and Freeston, 2001). This update also compares data from 1995 presented at the World Geothermal Congress 1995 (WGC95) in Florence, Italy (Freeston, 1996). As in 1995 and 2000, an effort was made to quantify geothermal (ground-source) heat pumps data. Final update papers were received from 68 countries, of which 60 reported some direct utilization of geothermal energy. Eleven additional countries were added to the list based on other sources of information. The 71 countries reporting direct utilization of geothermal energy, is a significant increase from the 58 reported in 2000 and the 28 reported in 1995. An estimate of the installed thermal power for direct-use at the end of 2004, from the current reports, is 27,825 MWt, almost a two-fold increase over the 2000 data, growing at a compound rate of 12.9% annually. The thermal energy used is 261,418 TJ/year (72,622 GWh/yr), almost a 40% increase over 2000, growing at a compound rate of 6.5% annually. The distribution of thermal energy used by category is approximately 33% for geothermal heat pumps, 29% for bathing and swimming (including balneology), 20% for space heating (of which 77% is for district heating), 7.5% for greenhouse and open ground heating, 4% for industrial process heat, 4% for aquaculture pond and raceway heating, <1% for agricultural drying, <1% for snow melting and cooling, and <0.5% for other uses. |