Abstract: The invention provides an underwater energy storage system (UW-ES system) comprising a reservoir structure (5), which is resting at the bottom (4) of a waterbody (1), such as a sea, an ocean, a waterway, etc. The reservoir structure has a pressurizing reservoir (7A, 7B) with a deformable wall structure (17A, 17B) and a depressurizing reservoir (8A, 8B) with a rigid wall structure (6, 14, 18A, 18B), which are holding a working liquid (9) separated from the water (2) of the water body. Energy is stored and retrieved by displacing part of the working liquid from the depressurizing reservoir into the pressurizing reservoir, and vice versa, respectively. Therein use is made of the hydrostatic pressure of the water (2) acting on the deformable wall structure of the pressurizing reservoir. The UW-ES system is compact and economical, and allows for highly synergistical integration with various power take-off systems.

Abstract: The invention provides an underwater energy storage system (UW-ES system) comprising a reservoir structure (5), which is resting at the bottom (4) of a waterbody (1), such as a sea, an ocean, a waterway, etc. The reservoir structure has a pressurizing reservoir (7A, 7B) with a deformable wall structure (17A, 17B) and a depressurizing reservoir (8A, 8B) with a rigid wall structure (6, 14, 18A, 18B), which are holding a working liquid (9) separated from the water (2) of the water body. Energy is stored and retrieved by displacing part of the working liquid from the depressurizing reservoir into the pressurizing reservoir, and vice versa, respectively. Therein use is made of the hydrostatic pressure of the water (2) acting on the deformable wall structure of the pressurizing reservoir. The UW-ES system is compact and economical, and allows for highly synergistical integration with various power take-off systems.

Abstract: The invention relates to extracting kinetic energy from surface waves. Therein, at least one float (8) is kept floating in the area of the surface waves, while a working fluid is held in a reservoir structure (2, 3). The float is connected to a fluid displacement structure in such manner that an individual surface wave, which causes an upward stroke of the float, moves the working fluid within the reservoir structure in such manner that the potential energy of the working fluid is increased. Before the wave has reached the float, the wave is detected by a sensor (7). Based on said detection, a prediction is calculated of the amount of kinetic energy available in the wave. Tuned to said prediction, an energy transmission structure of the fluid displacement structure is adjusted for realizing the energy conversion.

Abstract: The invention relates to extracting kinetic energy from surface waves. Therein, at least one float (8) is kept floating in the area of the surface waves, while a working fluid is held in a reservoir structure (2, 3). The float is connected to a fluid displacement structure in such manner that an individual surface wave, which causes an upward stroke of the float, moves the working fluid within the reservoir structure in such manner that the potential energy of the working fluid is increased. Before the wave has reached the float, the wave is detected by a sensor (7). Based on said detection, a prediction is calculated of the amount of kinetic energy available in the wave. Tuned to said prediction, an energy transmission structure of the fluid displacement structure is adjusted for realizing the energy conversion.