Abstract: In a method of storing energy in a two-vessel system, in which one vessel (1) containing a first substance (2) comprising two components, one of which is driven off from and is caused to become absorbed by the other component, respectively, at the supply of energy to and the withdrawal of energy from the system, respectively, energy is stored in the system by pumping said one component out of said one vessel (1).A system for carrying out this method comprises a two-vessel system, in which one chamber (1) contains a first substance (2) which comprises two components, one of which may be driven off from the other component, which on its side has the capability of absorbing said one component. The system also comprises an energy converter (6) adapted for the sucking or pumping out of said one component and which is incorporated in a conduit (4) connected to said one chamber (1).Thanks to the above method and system it has become possible to store mechanical or kinetic energy, e.g.

Abstract: A space is cooled by gasifying or vaporizing a first, preferably liquid substance in a first container located in said space. The gas or vapor thus formed is conducted into a second container located outside the space and containing a second substance generating a lower gas pressure than said first substance at the same temperature, preferably by being chemically bound thereby. Said gas or vapor is absorbed by the second substance, which shall possess the quality of forming a porous, substantially rigid body in its container after heating or regeneration in vacuum. The second substance is comprised of sodium sulphide, at least as its major ingredient.

Abstract: Heat energy is stored chemically in and extracted from an energy accumulator containing a substance which contains less liquid in the charged, high-energy condition of the accumulator than it does in the discharged low-energy condition of the accumulator, which is associated with vapor condensing and generating means which is maintained at a low temperature as compared with the accumulator in which a liquid container is comprised. Vapor is driven off from the accumulator substance and transferred to the vapor condensing and generating means when energy is stored in the accumulator, and is returned to the accumulator when heat energy is extracted therefrom. The system comprising the accumulator and said vapor condensing and generating means is maintained substantially free from other gases than said vapor.