Wave energy capture by an omnidirectional point sink oscillating water column system

Abstract

The Oscillating Water Column (OWC) is one of the most popular Wave Energy Convertor (WEC) technologies, but the energy conversion efficiency is still very low and is a bottleneck to limit its application and commercialization. A novel OWC system comprising of a cylindrical OWC WEC and a parabolic wave reflector was proposed and a revolutionary breakthrough in the hydrodynamic efficiency was obtained. To further validate this new concept, three independent model domain scenarios are developed using the open-source computational fluid dynamics software OpenFOAM. The first simulation model investigates the hydrodynamic efficiency of the OWC in open sea conditions and the second scenario investigates the performance of the OWC when it is located adjacent to a solid, vertical wall which is orientated perpendicularly to the incident wave direction. The third model consists of a vertical wall with a parabolic opening in plan view and the OWC is located at the parabolic focal point. This novel system combines the directionally independent wave energy capture of a cylindrical OWC WEC with the particular energy focussing attribute of a parabolic reflector. The hydrodynamic efficiency performances are compared among the three cases. The hydrodynamic efficiency in the case of the OWC located adjacent to the straight solid breakwater is approximately 200% more efficient than the open seas condition. However, the hydrodynamic efficiency in the case of the OWC located at the parabolic breakwater focal point greatly outperforms the other cases and a hydrodynamic efficiency increment in the order of 650% is realized compared to the open seas condition. These findings have considerable significance for the future application of ocean wave energy convertors and their use as a viable and sustainable technology to meet the world’s energy requirements.