Direct-drive ocean wave-powered batch reverse osmosis

Ocean waves provide a clean, reliable source of energy making them a viable energy source for desalination, especially in coastal communities and island nations. However, large capital costs render current wave-powered desalination technologies economically infeasible. This work presents a configuration for ocean-wave-energy-powered batch reverse osmosis. The proposed system uses seawater as the working fluid in a hydro-mechanical coupling and replaces the reverse osmosis high-pressure pump with a hydraulic converter for direct-drive, allowing for minimal intermediary power conversions, which leads to fewer parts necessary for operation and higher efficiencies. The concept was analyzed with MATLAB and Simulink to model the transient energy dynamics of the wave energy converter, power take-off system, and desalination load. The coupling, incorporating energy recovery, could achieve an SEC and LCOW as low as 2.30 kWh/m³ and 1.96/m³, respectively, for different sea states and a second law efficiency of 0.461. The results of the model were validated at the sub-system level against existing literature on wave energy models and previous work completed on batch reverse osmosis models. This system is the first to combine these two technologies. SEC and LCOW values were validated by comparing to known and predicted values for various types of RO systems.