Efficiency of Wave Energy Converters off the Sicilian Channel

This paper presents a preliminary analysis on efficiency of wave energy converters off the Sicilian Channel (Italy) carried out using the SNL-SWAN spectral model (”Sandia National Laboratories – Simulating WAves Nearshore”). This open source numerical code makes possible to calculate the power extracted from wave energy converter (WEC) devices, arranged in arrays. The WEC arrays were located parallel to the coastline, near the 20 m bathymetric isoline. Three devices were tested: Pelamis, Wave Dragon and Oyster 2; one of the input data of the numerical model is the WEC power matrix, expressed as a function of the wave height and period. This matrix was determined experimentally by the prototype manufacturers and it allows to compute the energy flux that can be extracted, depending on the significant wave height and on the peak period. Wave climate has been obtained from the Mazara del Vallo wave buoy dataset, covering the years from 1995 to 2005. The numerical model analysis results include the comparison between the energy flux distribution both in the case of presence of WECs and in their absence. The results obtained through the nearshore analysis allowed to assess the devices efficiency. Among the simulated devices only the Oyster 2 had a high value efficiency whereas for the other two devices lower power values were obtained. This results because the prototypes were designed considering the ocean wave conditions, which are of an order of magnitude higher than the conditions that occur in a closed sea basin, as is the Mediterranean Sea.