Introduction to Geothermal Energy

Abstract

This paper was prepared for the 43rd Annual California Regional Meeting of the Society of Petroleum Engineers of AIME to be held in Bakersfield, Calif., Nov. 8–10, 1972. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers Office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Briefly touches on the present status of development and future potential of geothermal energy. Compares production and reserve estimates including the units and terminology employed in energy calculations of the infant geothermal energy industry with those of the petroleum industry. Discusses the importance of basic thermodynamics to obtain an understanding of the part that steam and hot water play in geothermal energy. Energy is the capacity for doing work. Heat is energy. Geothermal heat is a common source of extractive energy quite widely distributed like oil, gas and coal. The heat is largely stored in rock, sometimes referred to as magma or magmatic rock. Water and steam provide the means of transferring the heat at depth to shallower measures. Both conduction and convection of heat are evidenced in the transfer process. Water and steam are also the agents through which geothermal heat escapes to the surface in hot springs and fumaroles. The geothermal energy industry is just now in its infancy. Some liken it to the state of the oil industry just after the turn of this century - about the time of the Lucas gusher at Spindletop. Geothermal electric power is now being produced in 6 countries - the United States, Italy, New Zealand, Japan, Russia and Iceland - and generating plants are under construction in Mexico and El Salvador. A half dozen other countries are rapidly developing their steam and hot water resources. The Geysers Area, in Sonomo Co., California, about 80 miles north of San Francisco, is the only geothermal field presently supplying commercial electric power in North America. Three companies, Magna and Thermal Power and Union Oil of California, act Power and Union Oil of California, act together to sell steam to the Pacific Gas and Electric company. At the present time, about 192 megawatts of electricity are being generated and plans are to provide an additional 110 MW per year to the system. 192 megawatts is 192,000 kilowatts. This amount would supply the electrical power requirements of a city of 200,000 population, about the size of Sacramento.