| Abstract |
Of all energy sources found on earth in various forms, by far the largest is thal stored in "hot dry rock" strata of the earthÃs crust, within reach of modern drilling techniques. This accessible resource base is 300 times larger than all sources of fossil energy resource fuels consisting of oil, gas, and coal. This paper presents a method by which the thermal energy in hot dry rock might be transferred to a multiple set of water-filled pipe loops radially disposed about a large central riser connected to the radial loops at top and bottom. The down-flowing water in the radial loops, which reach far out from the central riser, gathers heat from the rock strata as it descends, reaching maximum temperature at the bottom where the central riser gathers all of the down-flow from the radial loops. The riser then delivers this water to the surface by natural convection circulation caused by the hydraulic head difference between the colder down-flow water and the hotter up-flowing water, thus requiring no auxiliary pumping power. At the surface the thermal energy of water is transferred to a steam power cycle, either directly by flashed steam or through a heat exchanger. The water thus cooled then enters the down-flowing loops by a ring-manifold at the top for another heat gathering circuit. To account for draw-down in the rock temperature the return down-flow to the radial loops may be cycled, especially at low night time demand, to allow for heat recovery in this rock. |