• Energy Research

Overtopping-type wave power conversion devices represent one of the most promising technology to combine reliability and competitively priced electricity supplies from waves. While satisfactory hydraulic and structural performance have been achieved, the selection of the hydraulic turbines and their regulation is a complex process due to the very low head and a variable flow rate in the overtopping breakwater set-ups. Based on the experience acquired on the first Overtopping BReakwater for Energy Conversion (OBREC) prototype, operating since 2016, an activity has been carried out to select the most appropriate turbine dimension and control strategy for such applications. An example of this multivariable approach is provided and illustrated through a case study in the San Antonio Port, along the central coast of Chile. In this site the deployment of a breakwater equipped with OBREC modules is specifically investigated. Axial-flow turbines of different runner diameter are compared, proposing the optimal ramp height and turbine control strategy for maximizing system energy production. The energy production ranges from 20.5 MWh/y for the smallest runner diameter to a maximum of 34.8 MWh/y for the largest runner diameter.

Characterizing wave climate is crucial for coastal and offshore engineering applications. Reanalysis models, such as ERA5, are increasingly used due to their efficiency and lower costs compared to in situ measurements. However, their accuracy has not been thoroughly examined. This study addresses this gap by calibrating wave data from the ERA5 dataset with the available years of measurements from wave buoys in the Central Mediterranean Sea, specifically near Ponza, Cetraro, and Civitavecchia. A calibration approach was developed to adjust ERA5 wave data by aligning the model predictions closely with the co-located wave buoy observations. Results indicate that ERA5 systematically underestimates significant wave heights and periods, leading to an underestimation of wave power by up to 42% compared to buoy data. Calibration improved alignment between ERA5 and buoy measurements, enhancing wave energy representation and increasing estimated wave power by 35–48% annually. These findings underscore the importance of calibrating reanalysis datasets like ERA5 with in situ data to accurately assess wave energy potential, particularly in regions where model data may not fully capture local wave conditions. The outcomes provide valuable insights for wave energy projects in the Central Tyrrhenian Sea and similar semi-enclosed seas.

This paper presents a Coastal Vulnerability Assessment (CVA) of a microtidal beach located on the Ionian Sea in Calabria region (southern Italy) in order to examine the influence of the different run-up equations on CVA score and propose mitigation measures for the most vulnerable parts of the beach. The coastal area has been severely eroded by extreme wave storms, which have also damaged important archaeological structures located on a nearby cliff. A typical 1 year return period (Tr) storm, associated with the recent criticalities, was chosen to test the different run-up formulas (Holman (1986), Mase (1989) Stockdon et al. (2006) and Poate et al. (2016)) on a number of beach profiles in order to check the sensitivity of the CVA calculation with regard to the different run-up equations. The obtained results provide evidence that different run-up levels often give rise to different CVA scores. Based on vulnerability results, some mitigation measures have been proposed for the beach in front of the archaeological area, based on submerged detached breakwater and an adherent gabion wall for the cliff defence.

OBREC is the acronym that stands for Overtopping Breakwater for Energy Conversion. It is a multifunctional device aimed to produce energy from the waves, while keeping the harbour area protected from flooding. In this paper, the inclusions of a berm to reduce wave reflection, the shape of the sloping plate to maximise wave overtopping and the reservoir width and the crown wall shape to maximise wave energy capture while keeping the harbour safety were analysed to optimize the hydraulic and structural performances of the device. Several configurations were numerically investigated by means of a 2DV RANS-VOF code to extend the results already obtained during previous experimental campaigns. The wave reflection coefficient, the average wave overtopping flows and the wave loadings along the structure are computed, compared with existing formulae and discussed with reference to the OBREC prototype installed in the Port of Naples.

The reliability of Computational Fluid Dynamics (CFD) in reproducing qualitative and quantitative features of loadings exerted by waves on Seawave Slot-cone Generators (SSG) has been investigated via 17 numerical experiments, conducted with the suite Flow 3D. The geometry of the Wave Energy Converter (WEC), as well as the characteristics of the foreshore in front of it, were identical to those used by the authors in a laboratory study, carried out on a small scale model of a pilot plant to be located along the West Norwegian coasts; the similitude of the layouts allowed an in depth comparison between the results. A good agreement has been generally found between physical and numerical experiments, apart from some aspects of the wave–structure interaction that, however, can be considered secondary for engineering purposes.

Brazil has one of the largest electricity markets in South America, which needs to add 6000 MW of capacity every year in order to satisfy growing the demand from an increasing and more prosperous population. Apart from biomass, no other renewable energy sources, besides hydroelectricity, play a relevant role in the energy mix. The potential for wind and wave energy is very large. Brazil's Santa Catarina state government is starting a clean energy program in the state, which is expected to bring more than 1 GW of capacity. Assessment of wave energy resources is needed along the coastline. This work studied the potential wave energy along the north-central coasts of Santa Catarina, in Southern Brazil, by analysis of the hindcast data from the European Centre for Medium-Range Weather Forecasts (ECMWF). The annual offshore wave power was found to be equal to 15.25 kW/m, the bulk of which is provided by southeastern waves. The nearshore energetic patterns were studied by means of a numerical coastal propagation model (Mike21 SW). The mean wave power of 20 m isobaths is 11.43 kW/m. Supplementary considerations are drawn on realistic perspectives for wave energy converters installations.