PERFORMANCE ANALYSIS AND OPTIMIZATION OF A WAVE ENERGY-BASED ZERO-LIQUID-DISCHARGE HYBRID DESALINATION SYSTEM

The demand for freshwater is increasing globally, particularly in areas with limited water resources. Desalination, the process of removing salt and other minerals from seawater, is one solution that can help meet this demand. However, traditional desalination methods can be energy-intensive and generate significant amounts of waste. To help address these issues, a hybrid wave-to-water desalination system that combines reverse osmosis (RO) with supercritical water desalination (SCWD) can be used to produce freshwater from seawater. SCWD is used to treat the brine produced by RO, while the RO system produces fresh water at a lower energy cost. The system utilizes a wave energy converter (WEC) to harness the energy of ocean waves to power the desalination process by using the motion of waves to directly pressurize the seawater feeding into the RO system. Using ocean waves as an energy source makes the system renewable and reduces the carbon footprint of the desalination process. This paper presents a numerical model of a small-scale zero-waste desalination system powered by off-grid renewable energy along with a sensitivity analysis to determine the optimal configuration of key parameters of the system. An oscillating surge wave energy converter (OSWEC) was selected for the current study to directly pressurize the ocean water to meet the minimum pressure requirement of the RO. The numerical model of the water desalination system was developed using MATLAB-Simulink. WEC-Sim was used to develop the wave energy converter subsystem. A sensitivity analysis was conducted using an irregular wave pattern with a wave height of 0.117 m and a period of 1.68 s to determine the optimal combination of the power take-off (PTO) volumetric displacement, accumulator size, and RO membrane type for the system. Results showed that the type of RO membrane and the PTO volumetric displacement had a much larger impact on the water production rate than the accumulator volume.