Iceland is rich in geothermal resources due to the volcanic activity, and heat flow through the crust is several times higher than the world average. Traditionally the geothermal fields are divided into high- temperature fields, where temperature above 200°C is found at 1 km depth, and low-temperature fields, in which temperature is lower than 150°C in the uppermost kilometre. Some 30 high temperature fields have been identified in Iceland, all within the active volcanic zone as shown in Figure 1. Geothermal energy has become the main source of energy in Iceland supplying over 65% of the primary energy used in the country. The United States have the highest installed capacity, followed by the Philippines and Indonesia. Three European countries are amongst the TOP 10: Turkey, Italy, and Iceland.