The Ohio State University

Abstract:

Geothermal energy may become a practical global heat energy source when engineers and earth scientists focus upon the widespread existence of warm or hot subsurface rock in regions other than those with active volcanism. There are numerous regions where significant Tertiary, Quaternary and Recent igneous intrusive complexes have occurred and active volcanism has ceased or is dormant. These regions contain significant subsurface heat and are relatively safe for investment of the resources and technological development for heat energy recovery. Examples of the former active regions are the southeastern Hawaiian Islands, Mt. Vesuvius, Stromboli and the Central American Volcanic Chain. Examples of the latter are Yellowstone NP, the Snake River Plain and the Cascade Mtns. of the Pacific Northwest. This seminar concerns geothermal heat recovery from closed recirculation systems, not heat recovery from release of subsurface steam or hot brines in volcanically active regions.

Heat content of intrusive magma depends upon magma type (hence temperature), magma volume, and latent heat of crystallization. Cooling time following emplacement depends upon the thermal conductivities of magma, latent heat of crystallization, thermal conductivity of country rock and shape of the intrusive body. For this seminar only tabular intrusive bodies (dikes and sills) are considered. The thermal history of tabular bodies versus their thickness and rock type are considered. Total cooling time from intrusion temperature to ambient country rock temperature and heat energy release through time will be described. This heat energy release from cooling of intrusive bodies represents a major potential time dependent energy source.