Mining Geothermal Energy From Hot Dry Rock

by Roland A. Pettitt, (A.M.ASCE), Staff Member; Earth and Space Sic. Div., Los Alamos National Lab., Los Alamos, N.M. 87545,
Naomi M. Becker, (A.M.ASCE), Staff Member; Health Div., Los Alamos National Lab., Los Alamos, N.M. 87545,

Serial Information: Journal of Technical Topics in Civil Engineering, 1984, Vol. 110, Issue 1, Pg. 70-83

Document Type: Journal Paper


Geothermal energy is commonly considered to be available only in areas characterized by hot springs and geysers. However, the rock of the earth is hot at accessible depths everywhere, and this energy source is present beneath the surface in almost any location. The energy-extraction concept of the Hot Dry Rock (HDR) Geothermal Program, as initially developed by the Los Alamos National Laboratory, is to mine this heat by creating a man-made reservoir in low-permeability, hot basement rock. This concept has been successfully proven at Fenton Hill in northern New Mexico by drilling two holes to a depth of approximately 3 km (10,000 ft) and a bottom temperature of 200°C (392°F), then connecting the boreholes with a large diameter, vertical hydraulic fracture. Water is circulated down one borehole, heated by the hot rock, and rises up the second borehole to the surface where the heat is extracted and the cooled water is reinjected. A second-generation system, recently drilled to 4.5 km (15,800 ft) and temperatures of 320°C (608°F), entails creating multiple, parallel fractures between a pair of inclined boreholes. This system should produce 5 to 10 MW(e) for 20 years without adverse environmental impact.

Subject Headings: Thermal power | Boring | Water circulation | Rocks | Drilling | Temperature effects | Hydraulic fracturing | Reservoirs | New Mexico | United States

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