Solid-salt pressure-retarded osmosis with exothermic dissolution energy for sustainable electricity production

Abstract

Salinity gradient power (SGP) systems have strong potential to generate sustainable clean electricity for 24 hours. Here, we introduce a solid-salt pressure-retarded osmosis (PRO) system using crystal salt powders rather than seawater. Solid salts have advantages such as a small storage volume, controllable solubility, high Gibbs dissolution energy, and a single type of water intake, low pretreatment costs. The power densities with 3 M draw solutions were 11 W/m 2 with exothermic energy and 8.9 W/m 2 without at 35 bar using a HTI FO membrane (water permeability A = 0.375 L m -2 h -1 bar -1). These empirical power densities are ~13% of the theoretical value.