Method for generating electrical energy from a difference of ionic concentration of solutions (14,16), comprising the steps of: - providing a cell comprising at least two electrodes (18, 20) made of conductive material provided with a gap, with the electrodes connected in series to a load, and a switch opening or closing the circuit in which the load is inserted; - obtaining a high concentration phase, in which liquid in the cell, wherein the at least two electrodes are at least partially immersed, is mainly composed of solution having a higher ionic concentration as the other solution; - enabling a current to flow between the electrodes in the high concentration phase so that they are electrically charged in a charge phase; - obtaining a low concentration phase, in which liquid in the cell, wherein the at least two electrodes are at least partially immersed, is mainly composed of the other solution; and - allowing a current flow between the electrodes through the load in the low concentration phase so that they are discharged in a discharge phase, wherein the energy consumed during the charge phase is less than the energy extracted during the discharge phase, so that energy is extracted from the difference of ionic concentration of solutions,the method having four phases: 1) opening the switch and filling the cell with the solution having a higher ionic concentration; 2) closing the switch such that current flows through the electrodes, powering the load; 3) opening the switch and filling the cell with the solution having a lower ionic concentration; and 4) closing the switch such that current flows through the electrodes, powering the load, wherein the ionic concentration of said liquid in which the electrodes are immersed during said charge phase is higher than the ionic concentration of said liquid in which the electrodes are immersed during said discharge phase. - providing a cell comprising at least two electrodes (18, 20) made of conductive material provided with a gap, with the electrodes connected in series to a load, and a switch opening or closing the circuit in which the load is inserted; - obtaining a high concentration phase, in which liquid in the cell, wherein the at least two electrodes are at least partially immersed, is mainly composed of solution having a higher ionic concentration as the other solution; - enabling a current to flow between the electrodes in the high concentration phase so that they are electrically charged in a charge phase; - obtaining a low concentration phase, in which liquid in the cell, wherein the at least two electrodes are at least partially immersed, is mainly composed of the other solution; and - allowing a current flow between the electrodes through the load in the low concentration phase so that they are discharged in a discharge phase, 1) opening the switch and filling the cell with the solution having a higher ionic concentration; 2) closing the switch such that current flows through the electrodes, powering the load; 3) opening the switch and filling the cell with the solution having a lower ionic concentration; and 4) closing the switch such that current flows through the electrodes, powering the load, wherein the ionic concentration of said liquid in which the electrodes are immersed during said charge phase is higher than the ionic concentration of said liquid in which the electrodes are immersed during said discharge phase.