Abstract: The present invention relates to a hydraulic energy store (1) having a first (2) and a second fluid reservoir (6), the fluid levels (4, 12) of which extend at different heights, which are connected to one another via a turbine/pump arrangement (10) and during the operation of which a fluid (3) can be moved to and fro between the first (2) and second fluid reservoir (6) and energy can be converted in the process. The second fluid reservoir (6) is configured as a container which is arranged within the fluid (3) in the first fluid reservoir (2), wherein, during operation, the fluid level (12) in the second fluid reservoir (6) can be changed in such a way that, as a result, the immersion depth (ht) of said second fluid reservoir (6) in the first fluid reservoir (2) can be changed owing to buoyancy.

Abstract: The present invention relates to a hydraulic energy store (1) having a first (2) and a second fluid reservoir (6), the fluid levels (4, 12) of which extend at different heights, which are connected to one another via a turbine/pump arrangement (10) and during the operation of which a fluid (3) can be moved to and fro between the first (2) and second fluid reservoir (6) and energy can be converted in the process. The second fluid reservoir (6) is configured as a container which is arranged within the fluid (3) in the first fluid reservoir (2), wherein, during operation, the fluid level (12) in the second fluid reservoir (6) can be changed in such a way that, as a result, the immersion depth (h1) of said second fluid reservoir (6) in the first fluid reservoir (2) can Ere changed owing to buoyancy.