Design loads assessment for FOWT in the Mediterranean sea: a comparative analysis between alternative approaches

Existing guidelines recommend the use of the Environmental Contours method to estimate site-specific extreme environmental conditions, which critically influence both the operational efficiency and structural integrity of Floating Offshore Wind Turbines (FOWTs). While different approaches for computing such contours have been proposed in previous literature, the major source of uncertainty is still represented by the extreme data selection. In this respect, this study extracts Environmental Contour surfaces at four locations in the Mediterranean Sea relying on three different approaches, i.e., annual maxima, peak over threshold, and complete dataset, for environmental parameters representing the primary loading sources, namely hourly mean wind speed (Uw), significant wave height (Hs), and peak period (Tp). Results across all sites indicate that Hs peaks on the contour surfaces are overestimated when using the entire dataset compared to selecting only extreme values, underscoring the influence of the marginal distribution on environmental contour computations. Finally, the comparison of excitation levels across different sites supports the calibration of FOWT designs specifically for the Mediterranean Sea, as existing design criteria and recommendations are primarily tailored to the more severe conditions of the North Sea and the Atlantic Ocean. This approach offers potential cost-reduction benefits, aiding decision-making in a region with a high demand for renewable energy.