Abstract: A saturated non-convective solar pond is employed as an unmixing device in conjunction with reverse electrodialysis or pressure-retarded osmosis for power generation.

Abstract: The concentration of the solute in solution in a saturated non-convecting solar pond is greatest at a lower hotter level decreases continuously toward a higher cooler level and is saturated at all levels, thus preventing solute diffusion. In the customary operation of such saturated non-convecting solar ponds, the heat generated by incident radiation is absorbed in a bottom or lower layer. Because of the continuously decreasing density of solute which is near saturation from the lower to the upper layers, there is little salt convection and the pool tends to be further stabilized. Further, by heating due to absorption of the radiation largely at the lower level, a temperature gradient is maintained in which the upper layers remain cool, evaporation and consequent loss of heat is inhibited and the efficiency of the solar pond is improved. It has been discovered that a brine consisting essentially of an appropriate mixture of sodium carbonate (Na.sub.2 CO.sub.3) and sodium bicarbonate (NaHCO.sub.

Abstract: A method and apparatus are described for generating power utilizing press-retarded osmosis, in which a concentrated solution at a high hydraulic pressure is passed along one face of a semi-permeable membrane, and a dilute solution at a low hydraulic pressure is passed along the opposite face of the membrane to effect, by pressure-retarded-osmosis, the passage of at least a part of the dilute solution through the membrane forming a pressurized mixed solution. The potential energy stored in the pressurized mixed solution is converted to useful energy by depressurizing and repressurizing only the dilute solution.

Abstract: A method and apparatus are described for generating power utilizing reverse electrodialysis in which a concentrated ionic solution and a dilute ionic solution are passed through two pathways in a reverse electrodialysis unit including a membrane stack, whereby solute from the concentrated solution passes through the membrane to the dilute solution accompanied by the generation of an output electrical current and voltage. The concentrated and dilute ionic solutions are regenerated by thermal separation from the solutions exiting from the unit and are recycled back through the unit.