Improving the performance of salinity gradient power generation by a negative pressure difference

Abstract

Although salinity gradient power is a promising renemable energy source, its performance is limited by ion concentration polarization. We show that this problem can be alliviated effectively by applying a pressure gradient, the direction of which is opposite to the concentration gradient. The mechanisms involved are discussed in detail. BackgroundIon concentration polarization (ICP) can lower appreciably the effective concentration gradient across a nanopore, thereby reducing significantly the power generated in salinity gradient power harvesting. MethodsAttempting to alleviate ICP, we propose applying a negative pressure difference across the nanopore. Significant findingsDue to the enhancement in nanopore selectivity, the power generated can be improved appreciably. For example, at a surface charge density of −60 mC/m2, the maximum power can be raised up to ca. 167% when a pressure difference of −6 bar is applied. We show, for the first time, that applying a negative pressure difference is indeed effective.