Geothermal energy extraction system and method

Abstract

The present disclosure provides a system and process for extracting geothermal energy from a geologic formation. According to an embodiment of the method, coolant fluid is introduced into a first location, at a first height in the formation. The geologic coolant fluid is collected from a second location, at second height in the geologic formation. The second height is typically lower than the first height. Geologic coolant fluid introduced into the first location migrates through the geologic formation to the second location, extracting heat from the geologic formation. Pressure is lowered at the second location relative to the surrounding areas. In a particularly advantageous solution, the pressure is lowered at the second location using a pump, which is integrated into an energy conversion implement. The energy conversion implement is installed at, or close, to the second location. The pump delivers the cooled geologic coolant fluid to the first location.

1 . A geothermal energy extraction-method comprising:
 using a deep well pump to create a decreased pressure zone;   establishing a converging flow circulation in a hot geologic formation for convective heat exchange within the decreased pressure zone towards the pump;   circulating collected hot fluid through an energy-conversion unit for electrical energy production; and   re-injecting cooled coolant fluid into the geologic formation at a circulation injection point for zero net coolant fluid loss.   
     
     
         2 . The method of  claim 1 , further comprising establishing coolant fluid flow in a downward direction. 
     
     
         3 . The method of  claim 1 , further comprising engineering the pressure difference at any elevation between ambient (P A ) and low (P L ) pressure zones using a pump to overcome an upward-driving natural buoyancy pressure difference to create a net downward percolation plume. 
     
     
         4 . The method of  claim 3 , further comprising controlling the pressure difference between P A  and P L  during performance of the method in order to balance convective coolant fluid re-circulation within the natural, ambient hydrologic system in order to provide a desired degree of pressure-lowering. 
     
     
         5 . The method of  claim 3 , further comprising actively controlling the pressure difference between P A  and P L  according to a water level in a suction collection part of a production borehole. 
     
     
         6 . The method of  claim 1 , wherein the circulation injection point is selected close to an undisturbed water level in the geologic formation. 
     
     
         7 . The method of  claim 1 , wherein the pump comprises a submersible, high temperature pump and the energy conversion unit comprises a direct energy conversion unit and both the pump and the energy conversion unit are installed in the production borehole in situ and cooling power for the energy conversion unit is supplied from the surface at low temperature. 
     
     
         8 . The method of  claim 1 , wherein the energy conversion unit comprises a binary-phase heat exchanger comprising a boiler heated by the hot geothermal fluid, a turbine, a condenser comprising a heat exchanger cooled by coolant fluid circulation from the surface, an electrical generator driven by the turbine, and an electrical transmission line that carries electrical energy from a production borehole to the surface.