Survey of Energy Resources 2007
Geothermal - Utilisation
Geothermal utilisation is commonly divided into two categories, i.e. electricity production and direct application. Conventional electric power production is commonly limited to fluid temperatures above 150°C, but considerably lower temperatures can be used with the application of binary fluids (outlet temperatures commonly about 70°C). The ideal inlet temperature into houses for space heating is about 80°C, but by application of larger radiators or the application of heat pumps or auxiliary boilers, thermal water with temperatures only a few degrees above the ambient temperature can be used beneficially.
It is of great interest to note that among the top fifteen countries producing geothermally-generated electricity, there are ten developing countries (Fig. 11-4 ). Among the top fifteen countries in the direct use of geothermal, six are developing and transitional countries.