Method for installing a seal with seal membranes on a potential energy store having a hydraulic cylinder, in which a piston is arranged for the storage of energy in the form of potential energy of the piston, wherein the position of the piston relative to the earth's surface is variable, with a pump by means of which a hydraulic fluid can be pumped via lines into the hydraulic cylinder, so that the piston is raised, and with a generator for converting flow energy of hydraulic fluid which is displaced out of the hydraulic cylinder as the piston moves downward into electricity, wherein the seal is arranged between the hydraulic cylinder and the piston, comprising the steps of: a) providing seal membranes or groups of interconnected seal membranes, b) providing a crane on the top side of the piston or on the upper edge of the stroke cylinder, c) providing an upper anchor box, d) providing a lower anchor box, e) suspending the seal membranes or the interconnected groups of seal membranes from the crane, f) positioning the seal membranes or the groups of interconnected seal membranes with the crane so that the freely hanging end of the seal membranes or of the seal is located approximately at the level of the upper anchor box, g) connecting the seal membranes or the groups of interconnected seal membranes to one another so that a seal is formed, h) clamping the freely hanging ends of the seal membranes or of the groups of interconnected seal membranes or of the seal in the upper anchor box, i) moving the seal membranes or the groups of interconnected seal membranes or the seal further into the gap between piston and hydraulic cylinder by the crane so that the end of the seal membranes or of the groups of interconnected seal membranes or of the seal on which the crane engages is brought approximately to the level of the lower anchor box, j) releasing the connection to the crane, and k) clamping that end of the seal membranes or of the groups of interconnected seal membranes or of the seal which is situated at the level of the lower anchor box into the lower anchor box. a) providing seal membranes or groups of interconnected seal membranes, b) providing a crane on the top side of the piston or on the upper edge of the stroke cylinder, c) providing an upper anchor box, d) providing a lower anchor box, e) suspending the seal membranes or the interconnected groups of seal membranes from the crane, f) positioning the seal membranes or the groups of interconnected seal membranes with the crane so that the freely hanging end of the seal membranes or of the seal is located approximately at the level of the upper anchor box, g) connecting the seal membranes or the groups of interconnected seal membranes to one another so that a seal is formed, h) clamping the freely hanging ends of the seal membranes or of the groups of interconnected seal membranes or of the seal in the upper anchor box, i) moving the seal membranes or the groups of interconnected seal membranes or the seal further into the gap between piston and hydraulic cylinder by the crane so that the end of the seal membranes or of the groups of interconnected seal membranes or of the seal on which the crane engages is brought approximately to the level of the lower anchor box, j) releasing the connection to the crane, and k) clamping that end of the seal membranes or of the groups of interconnected seal membranes or of the seal which is situated at the level of the lower anchor box into the lower anchor box.