Productivity analysis of different design for OWC nearshore in breakwater in Pantelleria

The Kyoto Protocol was the fundamental crossroads to push countries around the world to focus heavily on the development of renewable energy. Over the years, research has not only aimed at optimizing existing technologies, but also at finding new ones to make the most of the energy potential that is provided to us by natural resources. The work carried out in this research focuses on the feasibility of installing a device in the breakwater of the port of Pantelleria to extract energy from the marine resource through a device that transforms the energy of the sea waves into electrical energy. The data relating to the characteristic wave resource of the studied site was extracted from the European Medium Weather Forecast Center (ECMWF) considering the influx of the seabed which reduces the power of the wave. The technology integrated into the protective wall is of the nearshore oscillating water column (OWC) type. Based on the type of wave resource, the OWC chamber is designed which affects characteristic dimensions such as the width of the chamber, the height of the air chamber, the opening of the chamber and the diameter of the Power Take-Off (PTO). The performance of three different types of structures are studied. The technologies designed are inserted into the ANSYS Aqwa software from which the hydrodynamic coefficients of the piston are extracted. From the interaction of the waves with the device installed in the breakwater, the displacement (along the z axis) of the water column inside the chamber was calculated. For the calculation of the thermodynamics of the OWC chamber, the air flow is considered as uncoverable. The data obtained by the software are in the frequency domain and through a series of Matlab programs, there is the conversion in the time domain. Subsequently they are inserted in the Simulink program where the dynamic behavior of the air chamber is analyzed and the electrical power generated by each single wave characteristic of the place is evaluated. The Wells type turbine used is the one installed in the OWC device in the port of Mutriku in Spain. The three devices are compared according to the maximum production of electrical power, electricity produced in a year of operation and equivalent hours. The structure with the sloping front wall turns out to be the one that produces the cheapest annual electricity. In conclusion, an economic cost analysis is carried out on all three configurations and the leveliezed cost of energy (LCOE) is estimated. In this way, it is evident that the configuration that produces the greatest amount of electricity per year does not guarantee a competitive electricity cost. The structure with the cone-shaped air chamber is the one that guarantees a lower LCOE but still too high compared to other renewable technologies on the market. The analysis does not take into account the expenses shared with the construction of the breakwater. The study could be useful for future research on the feasibility study of OWC devices with different designs installed in breakwater structures.