Exploiting offshore wind and solar resources in the Mediterranean using ERA5 reanalysis data

Commercial electricity production from marine renewable sources is becoming a necessity at a global scale. Offshore wind and solar resources can be combined to reduce construction and maintenance costs. In this respect, the aim of this study is two-fold: i) analyse offshore wind and solar resource and their variability in the Mediterranean Sea at the annual and seasonal scales based on the recently published ERA5 reanalysis dataset, and; ii) perform a preliminary assessment of some important features of complementarity, synergy, and availability of the examined resources using an event-based probabilistic approach. A robust coefficient of variation is introduced to examine the variability of each resource and a joint coefficient of variation is implemented for the first time to evaluate the joint variability of offshore wind and solar potential. The association between the resources is examined by introducing a robust measure of correlation, along with the Pearson's r and Kendall's tau correlation coefficient and the corresponding results are compared. Several metrics are used to examine the degree of complementarity affected by variability and intermittency issues. Areas with high potential and low variability for both resources include the Aegean and Alboran seas, while significant synergy (over 52%) is identified in the gulfs of Lion, Gabes and Sidra, Aegean Sea and northern Cyprus Isl. The advantage of combining these two resources is highlighted at selected locations in terms of the monthly energy production.