Method and apparatus for energy storage based on difference in concentration

Abstract

A method for extracting and storing, respectively, energy in the form of concentration gradients wherein a process of extracting energy comprising the steps of feeding stored gaseous working medium into a working volume (2), compressing the working medium in the working volume (2), spraying a dilute solution into the working volume (2) before or during compression, increasing the temperature of the working medium fed in the working volume (2) by compression, evaporating the dilute solution with the working medium of increased temperature, removing heat from the working medium by the evaporating solution, keeping the heat extracted from the working medium in the form of latent heat of the vapor in the working volume (2), further increasing the temperature of the working medium until the partial pressure of the vapor in it approaches the vapor pressure of a solution of higher concentration at a corresponding temperature, spraying a solution of higher concentration of a vapor pressure of up to 60% of the vapor pressure of the dilute solution into the working medium of an expanding and high solvent vapor content, condensing the vapor in the working volume (2) onto solution droplets of the atomized solution and thereby heating the solution droplets, transferring the heat energy of the heated solution droplets to the working medium through contact surfaces of the solution and the working medium, feeding the heat previously conveyed to the dilute solution vapor during the compression back into the working medium plus as much heat as the condensation heat of the warmer vapor to the solution of higher concentration exceeds the heat of evaporation of the dilute solution, using the heat thus fed for performing work by the expansion of the working medium, obtaining the work performed by the working medium, removing the working medium and the solution from the working volume (2) after the gaseous working medium of low relative humidity is getting into a state near to its initial state, separating the working medium and the solution and returning the working medium to a container (7) for working medium and returning the slightly diluted solution of higher concentration to one of a container (11) for solution of higher concentrations and an additional intermediate container (24). The invention also relates to an apparatus for implementing the method. The invention can be used in all fields, where electric or mechanical energy should be stored for later use, but especially for leveling out the production and consumption differences on electrical power grids.

Dependencies are inferred from the claim text.