250 results about "Electric power demand" patented technology

A method and apparatus are described for storing electrical power in the form of relative chemical potential between a concentrated solution, typically salt brine, and a dilute version of the same solution. To recover the power, the concentrated solution and dilute solution are supplied to a means for transforming the difference in their chemical potential into electrical power by such means as pressure retarded osmosis or reverse electrodialysis. In operation such means take in the concentrated and dilute solutions and exhaust a solution of intermediate concentration. The concentrated solution is supplied from a container such as a pond. It is generated by evaporation of the intermediate concentration solution in a second, separate pond, which receives the exhaust from the power generation means. The exhaust solution is concentrated by evaporation and is transferred into the first pond when the concentration has reached a sufficient level. To obtain a high evaporation rate in a relatively small evaporation area, the evaporation is enhanced to a rate faster than that obtained at the liquid surface of an open pond of the solution by employing electrical evaporation enhancement means. The electrical evaporation enhancement means is programmed to draw power from an electrical supply grid during periods when electricity demand is low and or when the cost of electricity is below or equal to an average cost over a period such as a diurnal cycle. When demand is high the enhancement is discontinued and the power generation means uses the stored concentrated brine to generate extra electrical power. Therefore the enhancement means would be used less than 30% of the time when the stored concentrated brine is being used to generate electrical power.