Geothermal energy has been produced commercially for nearly a century, and on the scale of hundreds of MW for over four decades both for electricity generation and direct use. The world direct-use energy production is about 37 TWh/ a (installed capacity of 10,000 MWt in nearly forty countries), and is, with the exception of China, mainly in the industrialized, and central and eastern European countries. Fourteen countries have installed capacities over 100 MWt. The main uses are space heating (33%), heat pumps (12%) for heating and cooling, bathing (19%), greenhouses (14%), aquaculture (11%) and industry (10%). The application of the ground source heat pump opens a new dimension in the scope for using the earth's heat, as heat pumps can be used basically everywhere and are not site specific as conventional geothermal resources