Combined power generation using geothermal and solar energy
Systems and methods are presented for enhancing energy production and storage by integrating solar energy with geothermal processes. In certain embodiments, a hybrid geothermal/solar system increases energy yield from a closed loop geothermal system, stores heat in a wellbore, enhances power generation from geothermal brine, and/or facilitates carbon dioxide sequestration or conversion to fuel, all preferably utilizing solar energy as a supplemental heat source.
1 . A method of generating electrical energy, comprising:
heating a working fluid in a closed loop geothermal system using solar energy;
wherein the closed loop geothermal system comprises a closed loop working fluid circuit having (a) a topside portion that is thermally coupled to a power cycle and (b) a downhole portion that is thermally coupled to a hot formation;
wherein the downhole portion is disposed within a wellbore to form an annular space between the wellbore and the downhole portion, and wherein the solar energy heats the working fluid in the downhole portion via a heat transfer fluid in the annular space; and
extracting thermal energy from the working fluid using the power cycle to thereby generate electrical energy.
2 . The method of claim 1 , wherein the working fluid is heated in the topside portion of the closed loop geothermal system.
3 . The method of claim 1 , wherein the working fluid is heated before thermal energy is extracted.
4 . The method of claim 1 , wherein the working fluid is heated after thermal energy is extracted and wherein the so heated working fluid is used to generate additional power.
5 . The method of claim 1 , wherein the working fluid is heated via a heat exchanger that is thermally coupled to a solar energy harvesting circuit.
6 . The method of claim 1 , wherein the wellbore is fluidly coupled to the closed loop geothermal system.
7 . The method of claim 1 , wherein the wellbore is thermally insulated by a low-k material comprising sand, a cementitious material, or fiberglass.
8 . The method of claim 1 , wherein the wellbore is co-located with the closed loop geothermal system.
9 . The method of claim 1 , wherein a second wellbore is proximal to the wellbore, wherein the solar energy heats a heat transfer fluid in the second wellbore, and wherein the working fluid in the downhole portion is heated by heat transfer through the hot formation from the second wellbore.
10 . The method of claim 9 , wherein the wellbore and the second wellbore are thermally coupled by a fracture network that is at least partially filled with a thermally conductive material comprising a proppant, water, zinc, or a carbonaceous material.
11 . The method of claim 9 , wherein the wellbore and the second wellbore are part of a wellbore grid comprising a grid controller that controls flow and/or temperature of the heat transfer fluid.
12 . A method of processing a geothermal brine, comprising:
producing from a formation a hot geothermal brine;
heating a working fluid of a power cycle using heat content of the hot geothermal brine, thereby causing the hot geothermal brine to become a cooled geothermal brine;
wherein the power cycle is thermally coupled to a topside portion of a closed loop working fluid circuit, wherein the closed loop working fluid circuit further comprises a downhole portion that is thermally coupled to a hot formation;
wherein the downhole portion is disposed within a wellbore to form an annular space between the wellbore and the downhole portion, and wherein solar energy heats the working fluid in the downhole portion via a heat transfer fluid in the annular space;
using solar energy to heat the hot geothermal brine and/or the working fluid to thereby increase power generation in the power cycle, and/or using the solar energy to heat the cooled geothermal brine to thereby evaporate water and concentrate a mineral in the cooled geothermal brine.
13 . The method of claim 12 , wherein the hot geothermal brine is produced by a geothermal well or an enhanced geothermal well.
14 . The method of claim 12 , wherein the power cycle is a closed Rankine cycle.
15 . The method of claim 12 , wherein the solar energy heats the hot geothermal brine before or after heating the working fluid.
16 . The method of claim 12 , wherein the solar energy evaporates all water in the cooled geothermal brine to produce a dry mineral product and distilled water.
17 . The method of claim 12 , further comprising a step of processing the cooled geothermal brine by electrochemical enrichment, ultrafiltration, or reverse osmosis to thereby isolate or enrich a metal salt or metal oxide.
18 . The method of claim 17 , wherein the metal salt or metal is a lithium salt or a lithium oxide.
19 . A hybrid geothermal/solar system, comprising:
(a) a closed loop geothermal system thermally coupled to a power cycle, and a solar energy harvester that is thermally coupled to the closed loop geothermal system to increase energy yield from the closed loop geothermal system; or
(b) a closed loop geothermal system thermally coupled to a heat storage wellbore, wherein a heat transfer fluid in the heat storage wellbore is heated by a solar energy harvester;
(c) a geothermal system configured to produce a geothermal brine from a geothermal wellbore, wherein the geothermal system is thermally coupled to a power cycle with a working fluid, and wherein a solar energy harvester is configured to increase power in the power cycle and/or to heat a cooled geothermal brine to thereby evaporate water and concentrate a mineral in the geothermal brine; or
(d) a carbon dioxide source that is configured to produce a concentrated carbon dioxide product and that is operationally coupled to a geothermal system and a solar energy harvester, wherein the carbon dioxide source is selected from the group consisting of a direct air capture unit, a decarbonization unit of a fossil fuel power plant, and an acid gas removal unit, wherein the geothermal/solar system is configured to use geothermal and solar energy to sequester the concentrated carbon dioxide product into a geological formation and/or to chemically convert the concentrated carbon dioxide product to a fuel product.