Pressure-Enhanced Osmotic Power Generation through Anodic Aluminum Oxide Membrane

Abstract

Osmotic energy, often called blue energy, is a promising renewable resource. Nanofluidic reverse electrodialysis, which utilizes nanoflows to generate power, has gained intensive attention as a promising technology for harvesting osmotic energy. However, efficiency challenges have hindered its widespread application. In this study, we proposed a strategy to enhance the osmotic energy harvesting efficiency by applying a pressure gradient, taking easily accessible anodic aluminum oxide membranes as the representative model. Our results demonstrate that the pressure difference across the membrane gives rise to a substantial enhancement in osmotic current for a wide range of pore sizes and salt ions. Specifically, a 1 bar pressure difference results in a 130% increase in osmotic current under a 1000-fold concentration gradient of potassium chloride solution. The pressure-enhanced osmotic power generation is attributed to the additional ion flux driven by pressure gradient and thus a higher electrical conductivity across the membrane. These findings highlight the potential of pressure-driven enhancements to improve the efficiency of blue energy technologies.