Development of a hybrid oscillating water column-overtopping device: Preliminary results of laboratory tests at scale 1:25 on the O2WC WEC

Abstract

This paper presents preliminary results of laboratory tests on a hybrid wave energy converter concept, the O2WC device. The O2WC aims at providing an upgrade of the classical OWC concept, allowing to store part of the wave energy under highly energetic sea states in a second chamber at atmospheric pressure, through overtopping phenomena. In this way, the maximum airflow rate and air pressure in the OWC chamber are reduced, aiding a safe functioning of the air turbine, and allowing to exploit the excess of energy instead of dissipating it. Results show that the decrease of the primary conversion efficiency of the OWC component of the device resulting from the decreased air pressure in the OWC chamber can be partially compensated by the additional energy stored in the overtopping chamber included in the device. The effect of the different design parameters is evaluated in the laboratory tests campaign presented in this work, allowing to select an optimal value of the height of the overtopping threshold from the second chamber of the device.