Evaluation of the performance of an OWC-OWEC hybrid wave energy converter integrated into a sloped breakwater

Abstract

The performance and hydrodynamics of a Hybrid Wave Energy Converter (HWEC) device, combining Oscillating Water Column (OWC) and Overtopping Wave Energy Converter (OWEC) technologies, inserted into a 2:3 sloped breakwater, are investigated. HWEC and individual OWC and OWEC, subject to the action of incident regular waves with periods from 6 to 14 s and wave heights of 1, 2, and 3 m, are studied and compared. Investigations are carried out by using the ANSYS-FLUENT software and adopting a numerical model based on the Reynolds Averaged Navier-Stokes equations, the Volume of Fluid method for the free surface flow, and a hybrid κ-ω SST turbulent/laminar model to deal with the involved complex phenomena. The HWEC device has higher efficiency than the individual OWC and OWEC devices and a more constant efficiency over the wave period interval, showing that both OWC and OWEC technologies complement each other and work well together. The maximum efficiency is achieved at the resonance period, around 9 s, reaching 77.6, 76.9, and 75.5% for incident wave heights of 1, 2, and 3 m, respectively. The energy balance analysis highlights that the HWEC device provides the best efficiency due to the limitation of the reflected wave energy and energy losses.