ABSTRACT
Heat is a form of energy and geothermal energy is literally the heat contained within the Earth that generates geological phenomena on a planetary scale. After the Second World War many countries were attracted by geothermal energy, considering it to be economically competitive with other forms of energy. Geothermal power can play a fairly significant role in the energy balance of some areas, and of the developing countries in particular. The geothermal gradient expresses the increase in temperature with depth in the earth’s crust. The mechanism underlying geothermal systems is by and large governed by fluid convection. The most common criterion for classifying geothermal resources is that based on the enthalpy of the geothermal fluids that act as the carrier transporting heat from the deep hot rocks to the surface. Direct heat use is one of the oldest, most versatile and also the most common form of utilization of geothermal energy.
