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

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/m² with exothermic energy and 8.9 W/m² 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.