| Abstract |
The Dry Hot Rock Geothermal Energy Program being conducted by the Basically we have proposed that man-made geothermal energy Los Alamos Scientific Laboratory has been described in detail by Smith et a1.lreservoirs can be created by drilling into relatively impermeable rock to a depth where the temperature is high enough to be useful; creating a large hydraulic fracture; and then completing the circulation loop by drilling a second hole to intercept the hydraulic fracture. Thermal power is extracted from this system by injecting cold water down the first hole, forcing the water to sweep by the freshly exposed hot rock surface in the reservoir / fracture system, and then returning the hot water to the surface where the energy is removed from the water by the appropriate power producing equipment. System pressures are maintained such that only one phase, liquid water, is present in the reservoir and the drilled holes. In the discussion to follow, the beneficial effects of thermal stress cracking, anticipated because of the cooling and thermal contraction of the rock, will be ignored. Instead, it will be assumed that the fluid flow is entirely confined to the gap between the impermeable rock surfaces and that heat is transferred to this fluid only by means of thermal conduction through the solid rock. |