| CPC F03B 3/10 (2013.01) [F03B 13/06 (2013.01); F03B 13/26 (2013.01); F05B 2260/422 (2020.08); Y02E 10/30 (2013.01); Y02E 60/16 (2013.01)] | 11 Claims |
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1. An energy storage system for storing energy in a waterbody, the waterbody having a water surface and a bottom surface, said bottom surface bounding a waterbody underground under the waterbody, wherein the energy storage system comprises:
a reservoir structure, which comprises a pressurizing reservoir and a depressurizing reservoir, each of which is configured for holding a working liquid beneath the water surface of the waterbody and separated from water of the waterbody in such manner that the working liquid within the pressurizing reservoir and the depressurizing reservoir and the water of the waterbody cannot mix with one another, wherein:
at least one deformable pressurizing subreservoir of the pressurizing reservoir is at least partly extending in the waterbody, has a liquid-impermeable deformable wall structure, and is configured for pressurizing the working liquid contained within the pressurizing reservoir by deformation of the deformable wall structure under influence of hydrostatic pressure of the water of the waterbody acting on the deformable wall structure, and
the depressurizing reservoir is arranged and configured for shielding the working liquid within the depressurizing reservoir from pressurization under influence of the hydrostatic pressure of the water of the waterbody;
an energy storing and retrieving subsystem configured for:
guiding the working liquid to flow from the pressurizing reservoir into the depressurizing reservoir, and vice versa,
storing energy by increasing a potential energy of the working liquid within the reservoir structure by displacing part of the working liquid from the depressurizing reservoir into the pressurizing reservoir, thereby causing said at least one deformable pressurizing subreservoir, by said deformation of the deformable wall structure, to expand against the action of said hydrostatic pressure of the water of the waterbody, and
retrieving stored energy by decreasing the potential energy of the working liquid within the reservoir structure by releasing part of the working liquid to flow from the pressurizing reservoir into the depressurizing reservoir, thereby causing said at least one deformable pressurizing subreservoir, by said deformation of the deformable wall structure, to collapse under the action of said hydrostatic pressure of the water of the waterbody;
wherein at least one buried depressurizing subreservoir of the depressurizing reservoir is an artificial structure, which has been buried under a vertical column of said waterbody underground, wherein said vertical column has a height of at least 5 meters, and
wherein said at least one buried depressurizing subreservoir is arranged at least 5 meters lower than said at least one deformable pressurizing subreservoir, which is extending in the waterbody, in the sense that, whereby in operation of the energy storage system, the working liquid inside said at least one buried depressurizing subreservoir is at least 5 meters lower than the working liquid inside said at least one deformable pressurizing subreservoir,
wherein a horizontal flatness ratio of said at least one buried depressurizing subreservoir is at least 2.0, said horizontal flatness ratio being defined as a quotient having a numerator and a denominator,
wherein the numerator is a square root of a surface area of a projection area of a horizontal reference plane, said projection area being obtained by vertically projecting said at least one buried depressurizing subreservoir onto said horizontal reference plane, and
wherein the denominator is an overall vertical height of said at least one buried depressurizing subreservoir.
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