Reducing ion concentration polarization by optimizing reservoir size in membrane-based salinity gradient power generation systems

Abstract

Salinity gradient power generation has attracted much attention for its green and sustainable advantages. However, previous studies have tended to overlook the effect of reservoir size in porous membrane systems on power generation (the reservoir size from nanometer to micrometer were applied for similar-sized nanochannels). In this work, we investigate the ion transport behavior and working performance in the salinity gradient power generation with different reservoir sizes. The results show that there is a significant dependence of reservoir length and edge height on the effect of salinity gradient power generation. Smaller reservoir length or larger edge height corresponds to weaker ion concentration polarization, larger effective concentration difference, and better power generation performance. The regulation of the energy conversion process by reservoir size is significant. The influence of reservoir size on salinity gradient power generation diminishes as the pore distance increases. Sufficiently large reservoir length and edge height are necessary if a more stable output power is to be obtained. This work illustrates the impact of reservoir size on power generation performance and its significant regulatory effect, providing useful information for future selection of reservoir size in porous membrane systems.