Desalinization of seawater is accomplished through the use of a forward osmosis process, which relies on a series of steps involving the opposition of various aqueous solutions across semi-permeable membranes. The process takes advantage of solutes having highly temperature dependent solubilities, as well as the relatively temperature indifferent solubility of NaCl(aq), the primary solute present in seawater. At least one utilized solute has a solubility directly dependent on temperature, and at least one utilized solute has a solubility inversely dependent on temperature.

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.

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

A hydraulic power generation system is provided for generating power using a pseudo-osmosis process which efficiently exploits the osmotic energy potential between two bodies of water having different salinity concentrations. The method and apparatus of the present invention does not require the use of a semi-permeable membrane or other specially formulated material, nor does it require heating or cooling of the fresh water or salt water solution. Moreover, the device may be used to recover energy from a wide variety of fresh water sources, including treated or untreated river run-off, treated waste-water run-off or effluent, storm-drain run-off, partly contaminated fresh water run-off, and a wide variety of other fresh water sources. The device is well suited to power production in a wide variety of geographic locations and under a wide variety of conditions. The invention has particular advantage for use in remote regions where electrical power generation by conventional means may be commercially infeasible or impractical.

An apparatus and method generates energy and, optionally, produces fresh water using osmotic processes that are driven by energy embodied in the heat of evaporation of water. An osmotic chamber transfers fresh water into a brine solution by osmotic pressure across an osmotic membrane. A mass transfer unit uses the osmotic pressure to maintain a high pressure concentrated brine solution within the osmotic chamber while providing for replenishing diluted brine solution with concentrated brine solution. The volume increase in the concentrated brine solution as it is diluted drives a motor to generate useful output energy. A concentrator uses dry air to concentrate dilute brine solution from the motor to a concentrated brine solution for return to the osmotic chamber.