Energy is stored by injecting fluid into a hydraulic fracture in the earth and producing the fluid back while recovering power and/or desalinating water. The method is particularly adapted to storage of large amounts of energy such as in grid-scale electric energy systems. The hydraulic 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.