A system for producing energy includes a solvent chamber, a pressure chamber and a semi-permeable barrier separating the solvent chamber from the pressure chamber. The solvent chamber for holds a solvent, and the pressure chamber hold a solute solution comprising a solute dissolved in a solvent. The semi-permeable barrier is permeable to solvent molecules and impermeable to solute molecules. Solvent molecules effuse across the semi-permeable barrier into the solute solution of the closed pressure chamber to increase the pressure of the pressure chamber, thereby generating energy in the form of hydrostatic pressure. A conversion device may convert the increased pressure in the pressure chamber to energy. The solute solution may be expelled and recycled after use.