Moving HDR technology toward commercialization

Conventional geothermal resources are currently being developed in many parts of the world where naturally occurring steam or hot water can be extracted from the earth. These hydrothermal resources, however, provide access to only a small fraction of the energy contained within the crust of the earth. In most regions, the heat of the earth is contained in hot rock at depth. The total amount of energy available in the form of hot dry rock (HDR) is extremely large. Estimates place the magnitude of the accessible HDR resource base worldwide at greater than 10 million quads (Armstead and Tester 1987) (1 quad equals 15 quadrillion Btu, or the energy content of about 180 million barrels of oil). For the past two decades, the Hot Dry Rock Program sponsored by the United States Department of Energy at the Los Alamos National Laboratory has been directed toward the development of methods to extract the vast amounts of energy which exist in HDR. The stated Level 1 Department of Energy objective for the Hot Dry Rock (HDR) Heat Mining Geothermal Energy Development Program is to {hor ellipsis} provide the technology to enable industrial hot dry rock projects to generate power at 5--8c/kWh bymore » 1997.'' (USDOE 1989) Fundamental to this objective is the ultimate goal of bringing HDR technology to commercial fruition. Indeed, all of the work done in this exciting research and development area will be for naught if we fail to move as rapidly as possible toward the utilization of this abundant and clean energy resource as one of the important elements in the future energy supply of the world. The purpose of this paper is to outline a path toward the commercialization of HDR heat mining technology, to discuss the potential obstacles in such a path, to propose techniques for overcoming those obstacles, and finally, to present a picture of what a commercial HDR facility may look like near the beginning of the next century. 14 refs., 3 figs., 2 tabs.« less