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 of controlling a quality of water used for storing and producing energy, comprising:
pumping the water down a well and into a hydraulic fracture in a rock formation around the well to store energy;
producing a portion of the water to provide a produced water up the well by reducing a pressure in the well before leak-off of the water from the hydraulic fracture;
measuring an amount of dissolved solid in the produced water to obtain a measured quality;
comparing the measured quality to a desired quality to obtain a compared quality;
diverting a first portion of the produced water to a treating process to produce treated water, wherein the first portion is determined based on the compared quality;
producing energy to provide a produced energy from a second portion of the produced water, wherein the second portion comprises the produced water less the first portion of produced water;
combining the treated water with the second portion of produced water to produce combined water comprising the desired quality; and
pumping the combined water down the well and into the hydraulic fracture in the rock formation around the well to store energy.
2. The method of claim 1 , wherein the dissolved solid comprises dissolved salt, and wherein the quality comprises a level of salinity.
3. The method of claim 1 , wherein the dissolved solid affects performance of the formation.
4. The method of claim 1 , wherein the dissolved solid causes scale build-up in the well.
5. The method of claim 1 , wherein the dissolved solid causes scale build-up inside the fracture.
6. The method of claim 1 , wherein the produced energy provides power for the treating process.
7. The method of claim 1 , wherein the treating process comprises a reverse-osmosis process.
8. The method of claim 7 , wherein the reverse-osmosis process comprises a pressure exchanger energy recovery device.
9. A method of storing and producing energy, comprising:
pumping a fluid down a well to a depleted tight gas reservoir to flow to a tip of a fracture of the depleted tight gas reservoir;
storing the fluid in the fracture as mechanical energy; and
before leak-off of the fluid from the fracture, reducing pressure in the well so as to produce a portion of the fluid to provide a produced fluid up the well and allowing pressure of the produced fluid to produce power.
10. The method of claim 9 , wherein the reservoir is a tight sandstone reservoir.
11. The method of claim 10 , wherein the reservoir is naturally hydrophilic.
12. The method of claim 9 , wherein the fluid is water.
13. The method of claim 12 , further comprising causing formation damage to decrease a relative permeability of hydrocarbons.