The PRecipitation atlas for Offshore Wind blade Erosion Support System (PROWESS) research, led by TNO, has shown that a substantial portion of offshore wind turbine blade damage occurs within just 12 hours each year under specific weather conditions.
TNO conducted a year-long study of precipitation in the North Sea. Analysis of the data revealed that around 30% of annual erosion damage to wind turbine blades happens when strong winds and intense rainfall coincide. This leading edge erosion (LEE) occurs when turbine tip speeds reach 325 km/h (90 m/s) at wind speeds above 63 km/h (10 m/s) and rainfall exceeds 7.5 millimetres per hour. Offshore erosion was found to occur at twice the rate of onshore erosion.
To obtain detailed wind and rain data, TNO deployed new measurement methods. Disdrometers, sensors that measure raindrop size, were placed at various locations in the North Sea. These measurements were used to analyse erosion risks and validate existing radar data. Using this research and weather simulations with a model developed by Whiffle, TNO and its partners created an 'erosion atlas' predicting when and where wind turbine blades are most at risk from rain. This tool allows wind farm operators to better plan preventive maintenance.
The study also found significant regional variations in the North Sea. In the northeast, blade coatings wear out about 20% faster than in the southwest due to stronger winds and heavier rainfall. New wind farms are set to be developed in this part of the North Sea from 2030.
The PROWESS research was conducted in collaboration with wind farm operators including Eneco, Shell, and Equinor.
