Enhancing Wave Energy Harvesting with a Submerged Crescent-Shaped Plate

Abstract

Wave energy converters (WECs) are devices that capture energy from waves, which is usually dictated by wave conditions. In this study, a rectangular wave farm with generic point absorber WECs was placed behind a submerged crescent-shaped plate to investigate whether the plate increases the amount of captured energy. A numerical model that describes the wave field around the plate, based on the boundary element method, was developed and validated with experimental results. When waves move past the plate, the combined effects of shoaling, refraction, and diffraction cause waves behind the plate to increase in height. Two parameters, the dimensionless energy extraction coefficient and the buoy coverage ratio, were investigated using long- and short-period waves with the aim of enhancing energy harvesting behind the submerged crescent-shaped plate. The results suggest that increasing the energy extraction coefficient and coverage ratio do not ensure increased harvesting efficiency; rather, these parameters may cause changes in the nearby wave field because of greater wave reflection and diffraction. A dimensionless energy extraction coefficient of 1.0 and a buoy coverage ratio of 0.1 were proposed as optimal parameters for all wave periods under the conditions of this study. In this rectangular wave farm, most energy was captured in the area closest to the submerged plate (30% of the total wave farm), and a lower buoy coverage ratio caused less wave reflection and diffraction in the wave field around the plate.