Modelling, Characterization and Testing of an Ocean Wave Powered Desalination System

Abstract

Development of alternative freshwater via desalination can address water scarcity and security. Meanwhile, sustainable renewable energy sources are critical to economically achieve seawater desalination. Marine renewable energy has tremendous potential to power the blue economy and is co-located with seawater. This study proposes an ocean wave powered reverse osmosis desalination system, which consists of an oscillating surge wave energy converter with a piston pump and a reverse osmosis desalination module with an accumulator on the shore. Seawater can be pressurized by the oscillating surge wave energy converter and pumped to the reverse osmosis desalination module as feed where it then produces permeate that is free of undesired molecules and larger particles. Numerical models considering potential flow theory of the wave energy converter and solution-diffusion theory of the reverse osmosis membrane were established. A 1:10 scaled prototype was designed, fabricated and tested in a wave tank based on the Froude scaling law. Comprehensive wave tank tests were implemented, characterized, and analyzed considering the water-energy nexus. Scaled tests resulted in the minimal specific energy consumption of 0.44 kWh/m3 under regular wave (wave period Ts = 4s /wave height Hs = 10 cm) with the corresponding optimal recovery ratio of 32%.