ABSTRACT
Ancient people and even primitive people of today have regarded the depths of the earth with horror, as the seat of hell and of malignant gods, due to natural phenomena like earthquakes and volcanic eruptions—a result of the heat energy present in the earth's crust. The Larderello field in Tuscany, Italy first began to produce electricity in 1904 and developed over the next 10 years to a capacity of 250 kW. Pioneering in the geothermal production of electricity, the Italians had tried operating reciprocating engines with this steam in the 1890s and today are the world leaders with respect to geothermal energy utilization. The natural heat of the earth is geothermal energy. It includes all the heat contained in about 260 billion cubic miles of rocks and metallic alloys at or near their melting temperatures, constituting the entire volume of earth except for a relatively thin, comparatively cool outer surface.
