Enhancing mass transfer in RO membranes powered by tidal energy using static mixers: a CFD study

This study presents a novel sustainable approach to desalination by integrating tidal energy with reverse osmosis (RO) technology, enhanced by Kenics static mixers (KSM) to improve mass transfer. A three-dimensional computational fluid dynamics (CFD) model analyzes the optimized ROKSM configuration, featuring three rows of KSM at a 30° twist angle, achieving a 1.6-fold increase in the Sherwood number (from 8.5 to 13.6 at Re = 300) and a 23% increase in water flux (from 13 to 16 L/m²h) by reducing concentration polarization. However, this comes with a 4.7-fold increase in pressure drop, partially mitigated by Energy Recovery Devices (ERDs), resulting in a net specific energy consumption of 2.2-2.5 kWh/m³. Tidal energy from global sites (600-1700 kW) provides feed pressures of 17-80 bar, with energy storage and pressure regulation ensuring stable RO operation despite tidal fluctuations. Techno-economic analysis indicates a potential levelized cost of water (LCOW) reduction of 15-20% (to 0.45-0.65 $/m³) under realistic conditions, though challenges in intermittency and costs require further validation. The integrated approach, validated with less than 5% error against experimental data, demonstrates significant potential for sustainable freshwater production, offering a scalable solution for coastal regions worldwide.