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Hydrological Problems Associated with Developing Geothermal Energy Systems a
Author(s) -
Pearl Richard Howard
Publication year - 1976
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1976.tb03092.x
Subject(s) - geothermal gradient , geothermal energy , hot spring , geology , volcano , earth science , hydrothermal circulation , geothermal heating , environmental science , hydrology (agriculture) , geochemistry , petroleum engineering , geophysics , geotechnical engineering , seismology
Geothermal energy–the naturally occurring heat of the earth's crust–has been used since earliest time by man for a variety of purposes. In recent times, wells have been drilled in close proximity to surface indicators of geothermal heat in an attempt to utilize this resource. The steam or hot water obtained from these wells has been used for agricultural and recreational purposes, to heat buildings, and to generate electricity. It has been estimated that by the year 2,000 between 30,000 Mw and 395,000 Mw of electricity can be generated in the United States with naturally occurring steam. Most geothermal systems of the world are located either in volcanic districts or at the margins of continental plates above subduction zones or spreading ridges. In addition, large quantities of heated ground water under pressure are found throughout the world in many large artesian basins. The various geothermal systems of the world can be divided into three major types based on the occurrence of associated ground waters: hydrothermal, geopressured and hot dry rock masses. In a hydrothermal system most of the heat energy is transferred by convective circulation of ground water and/or steam. Hydrothermal systems can be divided into three general types: vapor dominated, in which only dry steam is produced; wet steam, in which steam and hot water are produced; and hot‐water systems in which only hot water is produced. In the United States the most optimum location for the existence of a commercial geothermal deposit is either in the Gulf of Mexico artesian basin or in the mountainous States of the West where hydrothermal systems are found. At present, and probably for years to come, the primary geothermal exploration efforts will be aimed at discovering and developing high‐temperature hydrothermal systems to be used for generation of electricity. Typical problems that will be encountered in the exploration and development of such systems are: (1) Defining the type of hydrothermal system under investigation; (2) ground‐water flow direction, whether it is vertical or horizontal; (3) recharge rates and areas; (4) porosity and permeability determination; (5) water needs and consumptive usage; (6) disposal of waste fluids; and (7) legal and institutional considerations. A discussion of each problem area is presented. In order to solve many of these problems at the outset, it is believed that the geohydrologist should be an essential member of the exploration team.