Wave power technologies for the Mediterranean offshore: Scaling and performance analysis

The work investigates the potential of the Mediterranean offshore for wave electricity production, providing basin-scale results useful for future smaller-scale studies on specific areas of interest. At this purpose, the performance of a selection of offshore wave energy converters (WECs) is assessed all along the Mediterranean coastline (at 10 km resolution), on the basis of a 37-year hindcasted wave data and public WEC performance data. As the analyzed technologies were designed for more energetic wave climates, smaller devices have been considered, downscaled according to the Froude similarity criterion, in order to match Mediterranean wave conditions. At each location, the best device size is determined by simulating different scaled versions of the WECs and then selecting the scaling factor, which maximizes the mean annual capacity factor. The results show that large part of the Mediterranean coastline can be successfully exploited by properly downscaled versions of the WECs. More specifically, six of the studied wave power technologies can reach a capacity factor higher than 0.2 along 40% of the coastline and three WECs (AquaBuOY, Pelamis and Wavebob) can operate with a capacity factor exceeding 0.3 at 8% of the studied locations. The coastal regions with the highest WEC performance are of the Gulf of Lion, the Sicily channel, the Alboran Sea, the Libyan coast, Crete and Cyprus. The optimal size of the WECs at these locations is between 1/4 and 1/3 of the full WEC size and the resulting rated powers are between 10 and 30 kW. Noteworthy, a quite low performance is found for the most energetic areas of the Mediterranean (for example in western Sardinia), because a large part of the available energy is provided by extreme and rare events, for which the WEC efficiency is very low.