High resolution numerical modeling supporting the evaluation of the WaveSAX-2 power generation in the coastal area around the Civitavecchia port

The progress and future commercial success of each wave energy device is linked to the fact that the technology, the local wave motion characteristic and environmental condition are suitable to exploit the available wave energy resources in a specific coastal area. In the last years, several wave energy converters have reached an advanced development stage, such as the WaveSAX-2, an oscillating water column device suitable for been installed in existing coastal structures. Considering that the device can be installed directly on the breakwater wall or even inside the caissons, the impact on the marine environment can be considerably reduced. The device at scale 1:5 has been already tested in the Civitavecchia port (north eastern Tyrrhenian sea, Italy) in 2018 and 2020 leading to the evaluation of the power matrix (i.e. the expected power production for each local wave condition).

Thanks to the information obtained by the sea tests of the device, the wave energy potential exploited by WaveSAX-2 was evaluated, both in the offshore zone and in proximity of the Civitavecchia harbor structures, using the Mediterranean wave reanalysis product distributed as part of Copernicus Marine Service catalogue.

In the area around the Civitavecchia port, the main characteristics (height, period, direction) of the wave motion and the potential energy production of the device have been computed using the SWAN model that allows to obtain a high spatial resolution in the coastal zone. The model was successfully validated with wave data collected in 2017 and 2018 using an ADP instrumentation mounted within the Barnacle structure at 20 m depth in the northern area of Civitavecchia port.

The model results show that the highest energy levels are located in the northern and central part of Civitavecchia port where the breakwater structure has highly reflective features. These values resulted even greater than the energy found offshore. The southern part of the breakwater, which is protected by tetrapods with low reflective capacities, is instead characterized by lower values of wave energy. The study also highlights the improvement in the generation of the WaveSAX-2 due to the capacity of the new turbine to have a better efficiency in the exploitation of the lowest waves which are the most frequent ones in the study area.

The work demonstrates that high spatial resolution numerical modeling is a fundamental tool to analyze and accurately predict the wave energy potential exploitable by wave energy converters (WEC) in coastal areas affected by the presence of port structures. It also represents  a powerful tool for the optimization of the device array design, leading to maximize the energy production and minimize the environmental impact in the area.