| Keywords |
direct-use, low enthalpy, spas, balneology, space heating, aquaculture, greenhouses, heat pumps, crop drying, industrial, 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 1995 by one of the co-authors (Freeston) and presented at the World Geothermal Congress in Florence, Italy. For each of these updates since 1975, the recording of data has been similar, but not exactly the same. As in 1995, an effort was made to quantify geothermal heat pump data and the investment in geothermal energy development. Final update papers were received from 60 countries, of which 55 reported some form of geothermal direct utilization. An estimate of the installed thermal power at the end of 1999 (1995 in brackets) from the current reports is 16,209 MWt [8,660 MWt] utilizing at least 64,416 kg/s [37,050 kg/s] of fluid, and the thermal energy used is 162,009 TJ/yr [112,441 TJ/yr]. The distribution of the thermal energy used by category is approximately 37% for space heating, 22% for bathing and swimming pool heating, 14% for geothermal heat pumps, 12% for greenhouse heating, 7% for aquaculture pond and raceway heating, 6% for industrial applications, less than 1% each for agricultural drying, snow melting, air conditioning and other uses. The reported data for number of wells drilled was 1,028, work by professional over the five-year period was 3,363 pers on-years, and the total investment over the five years was 841 million US$, indicating minimum values. |