Seaports are highly energy demanding infrastructures and are exposed to wave energy, which is an abundant resource and largely unexploited. As a result, there has been a rising interest in integrating wave energy converters (WEC) into the breakwaters of seaports. The present work analyzes the performance of an innovative hybrid WEC module combining an oscillating water column (OWC) and an overtopping device (OWEC) integrated into a rubble mound breakwater, based on results of a physical model study carried out at a geometrical scale of 1:50. Before the experimental tests, the device’s performance was numerically optimized using ANSYS Fluent and WOPSim v3.11. The wave power captured by the hybrid WEC was calculated and the performance of the two harvesting principles discussed. It was demonstrated that hybridization could lead to systems with higher efficiencies than its individual components, for a broader range of wave conditions. The chosen concepts were found to complement each other: the OWEC was more efficient for the lower wave periods tested and the OWC for the higher. Consequently, the power production of the hybrid WEC was found to be less dependent on the wave’s characteristics.

Sea ports are infrastructures with substantial energy demands and often responsible for air pollution and other environmental problems, which may be minimized by using renewable energy, namely electricity harvested from ocean waves. In this regard, a wide variety of concepts to harvest wave energy are available and some shoreline technologies are already in an advanced development phase. The SE@PORTS project aims to assess the suitability and viability of existing wave energy conversion technologies to be integrated in harbor breakwaters, in order to take advantage of their high exposure to ocean waves. This paper describes the experimental study carried out to assess the performance of a hybrid wave energy converter (WEC) integrated in the rubble-mound structure that was proposed for the extension of the North breakwater of the Port of Leixões, Portugal. The hybrid concept combines the overtopping and the oscillating water column principles and was tested on a geometric scale of 1/50. This paper is focused on the assessment of the effects of the hybrid WEC integration on the case-study breakwater, both in terms of its stability and functionality. The 2D physical model included the reproduction of the seabed bathymetry in front of the breakwater and the generation of a wide range of irregular sea states, including extreme wave conditions. The experimental results shown that the integration of the hybrid WEC in the breakwater does not worsens the stability of its toe berm blocks and reduces the magnitude of the overtopping events. The conclusions obtained are therefore favorable to the integration of this type of devices on harbor breakwaters.

The present work optimizes the seakeeping performance of a displacement catamaran in head seas to operate as a fast crew supplier for an offshore platform at the Alentejo basin, Portugal. In order to assess the accuracy in predicting heave and pitch motions of fast displacement catamarans (assuming negligible interaction between demi-hulls in head seas), three codes based on the ordinary strip-method were compared: the open-source code PDStrip, an in-house code earlier developed at CENTEC in Técnico Lisboa (IST) and the commercial software Maxsurf. The codes were applied to a fast catamaran and a fast mono-hull, for which experimental data from model testing were available. Results indicated PDStrip (with transom terms) as the most suited to be used in the optimization procedure. The RMS vertical acceleration responses at the bow and the average Motion Sickness Incidence (MSI) at the passenger area were selected as objective functions to minimize. Extreme effects such as slamming and green water were neglected, even though they might occur. As an attempt to include a preliminary design of the general arrangement, the dimensions and position of the passenger area on deck were set in order to minimize motion sickness. Stability criteria from the High Speed Craft (HSC) Code were applied, as well as a constraint on the maximum total ship resistance, computed with empirical formulae that estimate the hull interference components. Slender-body theory was used to calculate wave resistance. The effects of horizontal clearance ratios S/LWL between 0.2 and 0.4 were studied with respect to resistance, stability and MSI. The method of Lackenby was used to generate hull variations from a parent model, for which combinations of LCB and Cb were imposed, varied within the range of +-10%. Finally, an operability assessment of the optimized catamaran operating at two different speeds was carried out based on limiting seakeeping criteria imposed by the HSC Code and DNV-GL in terms of the average 1% highest accelerations.