Hydraulic geofracture energy storage system with desalination
Energy may be stored by injecting fluid into a fracture in the earth and producing the fluid back while recovering power and/or desalinating water. The method may be particularly adapted to storage of large amounts of energy such as in grid-scale electric energy systems. The fracture may be formed and treated with resin so as to limit fluid loss and to increase propagation pressure. The fluid may be water containing a dissolved salt or fresh water and a portion or all of the water may be desalinated using pressure in the water when it is produced.
1. A method for storing and producing energy, comprising:
pumping a fluid down a well to a fracture to inhibit fluid transport away from the fracture, wherein the fluid comprises a sequence of reactants;
injecting a subsequent fluid down the well;
storing the subsequent fluid in the fracture as mechanical energy; and
before leakoff of the subsequent fluid from the fracture, reducing pressure in the well so as to produce a portion of the subsequent fluid up the well and allowing pressure of the produced fluid to produce power by allowing the pressurized fluid to escape through a turbine.
2. The method of claim 1 , wherein the fracture is in a rock matrix that lacks calcium-bearing minerals, wherein a first slug of the sequence of reactants comprises calcium chloride, wherein a subsequent slug of the sequence of reactants comprises sodium silicate.
3. The method of claim 2 , further comprising dehydrating any shale present in the rock matrix.
4. The method of claim 2 , wherein the calcium binds to clay surfaces and crosslinks with proximal clay particles.
5. The method of claim 2 , further comprising mixing the calcium with the sodium silicate in-situ down the well.
6. The method of claim 5 , further comprising producing a precipitate and a gel.
7. The method of claim 6 , further comprising clogging pores or micro-fractures with the gel.
8. The method of claim 1 , wherein the sequence of reactants is separated by spacers of an unreactive fluid.
9. The method of claim 1 , wherein the fracture is in a rock matrix that comprises calcium-bearing minerals, wherein a first slug of the sequence of reactants comprises sodium silicate or potassium silicate.
10. The method of claim 9 , further comprising mixing the first slug with the calcium-bearing minerals in-situ down the well.
11. A method for storing and producing energy, comprising:
pumping a fluid down a well to a fracture to inhibit fluid transport away from the fracture, wherein the fluid comprises a sequence of reactants;
injecting a subsequent fluid down the well;
storing the subsequent fluid in the fracture as mechanical energy; and
before leakoff of the subsequent fluid from the fracture, reducing pressure in the well so as to produce a portion of the subsequent fluid up the well and allowing pressure of the produced fluid to flow into a reverse osmosis unit for desalination.
12. The method of claim 11 , wherein the fracture is in a rock matrix that lacks calcium-bearing minerals, wherein a first slug of the sequence of reactants comprises calcium chloride, wherein a subsequent slug of the sequence of reactants comprises sodium silicate.
13. The method of claim 12 , further comprising dehydrating any shale present in the rock matrix.
14. The method of claim 12 , wherein the calcium binds to clay surfaces and crosslinks with proximal clay particles.
15. The method of claim 12 , further comprising mixing the calcium with the sodium silicate in-situ down the well.
16. The method of claim 15 , further comprising producing a precipitate and a gel.
17. The method of claim 16 , further comprising cross-linking clay surfaces with the precipitate.
18. The method of claim 16 , further comprising clogging pores or micro-fractures with the gel.
19. The method of claim 11 , wherein the sequence of reactants is separated by spacers of an unreactive fluid.
20. The method of claim 11 , wherein the fracture is in a rock matrix that comprises calcium-bearing minerals, wherein a first slug of the sequence of reactants comprises sodium silicate or potassium silicate.