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This work has been supported by the OCEANERA-NET project, SE@PORTS (Sustainable Energy at Sea Ports); reference OCEANERA/0003/2016, under the frame of Sociedad para el Desarrollo Regional de Cantabria S.A. (SODERCAN).

The OBREC is an overtopping structure which is integrated into a traditional rubble-mound breakwater to convert wave energy into electricity. The relatively simple geometry of this overtopping device, with a single frontal ramp and a reservoir, makes the technology suitable to be fully combined also with existing structures. OBREC has been deeply investigated over the last years with physical and numerical model tests, and it is still under development with the ongoing monitoring activities at full-scale in real environments focusing on the wave-OBREC interaction. A comprehensive review of the research studies during the last ten years is here presented. The paper contains some unpublished details on OBREC geometry and power take-off strategy. A special attention is also directed to the description of the full-scale prototype of OBREC at Naples harbour, where an experimental campaign is still continuing.

This paper presents an innovative vertical breakwater cross-section integrating an overtopping wave energy converter, named OBREC-V, and the analysis of its hydraulic performance and stability response to hydraulic loading. The structure is composed of a vertically-faced caisson with a sloping ramp on the top, a reservoir and a set-back crown-wall. The analysis of the structure is carried out by performing numerical simulations based on the Volume-Averaged Reynolds Averaged Navier-Stokes (VARANS) equations. The numerical simulations are performed to compare the performance of a traditional and innovative vertical caissons under the action of irregular waves, in terms of wave reflection, overtopping and wave acting forces. Results show that the reflection coefficients are lower than those computed in front of the traditional breakwater, with a reduction of up to the 40%. New formulations are proposed to better estimate the reflection coefficient and the wave overtopping at the rear side of the structure taking into account the non-conventional geometry of the device. The analysis of the forces indicate that the non-conventional geometry of the innovative OBREC-caisson increases the overall stability of the structure. The values of the safety factor against sliding, Cs, on innovative caissons are similar or greater than those calculated on the traditional vertical structure for almost all the tests. The downward force on the ramp and reservoir and the time lag between the vertical and horizontal forces, lead to a significant reduction of the maximum destabilizing forces Fs in the innovative breakwater, whose values range between 60 and 80% of the ones computed on the traditional structure. The obtained results show the co-benefits, in terms of functionality and hydraulic stability, that an OBREC-V entails with respect to a traditional vertical breakwater.

The Maldives are situated in the remote equatorial Indian Ocean, covering 900 km from north to south. The 26 coral atolls forming the archipelago are composed of sand and coral with a maximum height of about 2.30 m above the mean sea level. Periodic flooding from storm surges and the frequent freshwater scarcity are perceived by the population and the economic operators as the major environmental stresses. Moreover, the strong dependence on imported fossil fuels increases, even more, the environmental concerns. Diesel, in fact, still represents the main source of power generation, typically through privately managed small diesel sets. The real challenge for this area is to promote the environmental quality with socioeconomic growth. The present study aims to evaluate the strategic effectiveness to face these issues by wave and offshore wind energy. Resources using a 10-year hindcast dataset are here examined. The annual offshore wave power was found to range between 8.46 kW/m and 12.75 kW/m, while the 10 m and 100 m mean wind power density is respectively 0.08 kW/m2 and 0.16 kW/m2. Based on these results, an environmentally and socio-economically sustainable best-case scenario is constructed and two atoll islands (Malè and Magoodhoo) are specifically investigated. As a result, multifunctional structures and multi-use systems, which combine power generation, desalinization and coastal defence, are strongly recommended.

The Overtopping BReakwater for Energy Conversion (OBREC) is an overtopping type wave energy converter, totally embedded into traditional rubble mound breakwaters. The device consists of a reinforced concrete front reservoir designed with the aim of capturing the wave overtopping in order to produce electricity. The energy is extracted through low head turbines, using the difference between the water levels in the reservoir and the sea water level. This paper investigates the nature and magnitude of wave loadings exerting on various parts of the structure. The results improve the overall knowledge on the device behavior, completing the highlights from the complementary test campaign carried out in the same wave flume in 2012 (Vicinanza et al., 2014). The formulas provided have been used to design the first OBREC prototype breakwater in operation since January 2016 at Naples Harbour (Italy).

This paper constructs an optimal configuration assessment, in terms of the financial returns, of the Overtopping BReakwater for wave Energy Conversion (OBREC). This technology represents a hybrid wave energy harvester, totally embedded in traditional rubble mound breakwaters. Nine case studies along the southern coast of Western Australia have been analysed. The technique provides tips on how to estimate the quality of the investments, for benchmarking with different turbine strategy layouts and overlapping with the costs of traditional rubble mound breakwaters. Analyses of the offshore and nearshore wave climate have been studied by a high resolution coastal propagation model, forced with wave data from the European Centre for Medium-Range Weather Forecasts (ECMWF). Inshore wave conditions have been used to quantify the exploitable resources. It has been demonstrated that the optimal investment strategy is nonlinearly dependent on potential electricity production due to outer technical constraints. The work emphasizes the importance of integrating energy production predictions in an economic decision framework for prioritizing adaptation investments.

The Overtopping BReakwater for Energy Conversion (OBREC) is a new typology of overtopping wave energy converter (OTD) integrated into a traditional rubble mound breakwater. The device can be considered as an innovative non-conventional breakwater that has the same functions as the traditional structures with the added-valued of the energy production. The paper presents a comprehensive overview of the OBREC, offering a synthesis of the complete design process, from the results of the two complementary test campaigns in small scale carried out in 2012 and 2014 at Aalborg University, to the description of the full-scale device installed in Naples in 2016. The device represents the first OTD device in full-scale integrated into an existing rubble mound breakwater and it has been equipped by an instrumental apparatus to measure its response to the wave interaction. The monitoring of the full-scale device in the port of Naples, particularly during storm conditions, is aimed to study the scaling effects in wave loading and the overall performance of this breakwater-integrated OTD, included performance in terms of the energy production.

The accuracy of directional wave spectra sensors is crucial for obtaining accurate forecasts of ocean and coastal wave conditions for scientific and engineering applications. In this paper, a newly designed, low-cost GPS-based wave buoy, called the Directional Wave Spectra Drifter (DWSD), is presented. A field test campaign was conducted at the Gulf of Naples, Italy with the goal of comparing the directional wave properties obtained with the DWSD and with a nearly co-located bottom-mounted Acoustic Doppler Current Profiler (ADCP) from Teledyne RD-Instruments. The comparison shows a very good agreement between the two methodologies. The reliability of this innovative instrument and its low costs allow a large variety of applications, including the implementation of a global, satellite-linked, real-time open-ocean network of drifting directional wave spectra sensors and monitoring the sea-state in harbors to aid ship transit and for planning coastal and offshore constructions. The DWSD is currently in use to better constrain the wave energy climatology with the goal of optimizing the design of a full-scale prototype Wave Energy Converter (WEC) in the port of Naples, Italy.