Abstract

Heat emanating from within the earth is one source of geothermal energy. This vast repository of energy is generated from the decay of natural radioisotopes and heat from the molten core of the earth.

Natural sources of geothermal fluids for heating and bathing have been utilized since prehistoric times. The useful applications of hydrothermal resources depend on the temperature of the extracted fluid. Relatively low temperature fluids can be effectively applied for purposes such as greenhouse heating, fish farming, and especially space heating. Waters at higher temperatures can be used for a variety of industrial processes and the generation of electricity. Transportation of hot fluid over more than a few kilometers is often economically impractical. It is then possible to apply the power generated by hydrothermal energy in a variety of ways and at distant locations. The effeciency of electrical generation is directly related to the thermal quality of the resource. To successfully compete with the multitude of energy sources available, geothermal energy must be available and retrievable in both a convenient and an economical manner. Conditions have only been met using hydrothermal geothermal resources in the form of hot water and steam but these particular hydrothermal resources are limited. Most of the world's accessible geothermal energy is found in rock that is hot but contains limited fluid. Although research and development have demonstrated success in extracting thermal energy on a limited basis, the vast deeper hot rock resource has not yet been shown to be an economically feasible source of energy on a scale large enough for practical use.