The invention provides a potential energy store (100) having a hydraulic cylinder (110) in which a piston (120) for storing energy in the form of potential energy of the piston (120) is arranged, wherein the position of the piston (120) relative to the earth's surface can be varied, having a pump by means of which a hydraulic fluid (130) can be pumped via lines into the hydraulic cylinder (110) such that the piston (120) is raised, and having a generator for converting hydraulic energy of hydraulic fluid (130), which is displaced out of the hydraulic cylinder (110) as the piston (120) falls, into electricity, wherein a seal (400, 500, 600, 700, 701, 800, 900, 1000) or seal arrangement (1200, 1300, 1400, 1500) is at least partially arranged between the hydraulic cylinder (110) and the piston (120), characterized in that the seal (400, 600, 700, 701, 800, 900, 1000) or seal arrangement (1200, 1300, 1400, 1500) has at least one sealing section with a flexible support structure for absorbing the acting forces, said support structure being coated on one or both sides with a layer which is impervious to fluid and which serves for sealing against the passage of fluid, or said support structure being impregnated with a solidified material which is impervious to fluid.