Author(s): Victor Ramos; Tomas Calheiros-Cabral; Gianmaria Giannini; Ajab Majidi; Luciana Das Neves; Paulo Rosa-Santos; Francisco Taveira Pinto

Linked Author(s): Paulo Rosa-Santos, Francisco Taveira Pinto

Keywords: Wave Power; Low-Carbon Ports; Oscillating Water Column; Overtopping WEC; Wave Modelling

Abstract: Seaports present high-energy demands, which are mainly fulfilled by fossil-fuel sources. Consequently, seaports have turned into a significant source of air pollution, namely in terms of greenhouse gas (GHG) emissions. In this context, marine renewable energy (MRE) resources such as wave, tidal, and offshore wind appear as promising alternatives to supply part of the energy demands of ports. Against the foregoing backdrop, this study focuses on studying different wave energy-based solutions that have the ambition to contribute towards energy self-sufficiency of ports and to encourage the transition to a low-carbon and blue economy. For this purpose, the Port of Leixões (Portugal), which has a significant wave energy potential, appears as an excellent location to harness wave power for supplying energy to the port. Since an extension of the outer breakwater of the port is planned, the integration of a wave energy converter (WEC) into the new planned structure was considered. Therefore, this work studies the consequences of the new breakwater over the wavefield aiming at understanding the WEC’s performance. Accordingly, an accurate characterization of the wave conditions at the breakwater, accounting for the non-linear wave transformation processes that take place nearshore is required. Once the available wave resource is fully characterized, the performance of different WECs integrated into the outer breakwater of the port (e.g. OWC, overtopping, and hybrid devices) are analysed and compared in terms of energy production, overall efficiency, annual operation time and capacity factors. The WEC concept that offers the best results is a hybrid module combining an Oscillating Water Column and a multi-reservoir Overtopping Device. This device was designed to be integrated into a 20 m-wide section of the planned extension of the North breakwater of the Port of Leixões and its geometry was optimized for the wave conditions at the site. The device was tested in the centre of a 64 m-wide section of the breakwater, at the Faculty of Engineering of the University of Porto, Portugal. A wide range of working and extreme conditions were considered, as well as three characteristic water levels at site and a water level considering the predicted global sea-level rise due to climate change. Overtopping rates were measured and the stability of the armour layer, as well as the occurrence of scouring, were assessed using a point cloud laser scanner. Moreover, impact forces on the device and pore pressure inside the breakwater’s layers were measured using piezoresistive pressure sensors. These data will add significant knowledge about the h-WEC’s performance and its impact on the main function of a harbour breakwater - protection of the internal harbour. The preliminary results of this work will be presented and discussed in the paper.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221875

Year: 2022