According to new research conducted by the Netherlands Organisation for Applied Scientific Research (TNO) in collaboration with offshore wind farm operators such as Eneco, Shell, and Equinor, a substantial part of the damage that wind turbine blades suffer per year occurs across twelve hours of harsh weather conditions.
“We already knew that heavy rain significantly affects the rotating turbine blades, but the fact that nearly one-third of the erosion damage occurs in such a short time was a new insight” , said Harald van der Mijle Meijer , wind energy researcher at TNO.
The research project, called PROWESS (PRecipitation atlas for Offshore Wind blade Erosion Support System project), involved year-long detailed measurements of precipitation in the North Sea and an analysis of the data, which revealed that about 30 per cent of the annual leading edge erosion on wind turbine blades happens within just 12 hours of the year when strong winds and intense rainfall coincide.
The damage occurs when the tip speed reaches the maximum of 325 km/h (90 m/s) as wind speeds exceed 63 km/h (10 m/s) and rainfall exceeds 7.5 mm/h, according to TNO.
The analysis also showed that offshore damage occurs twice as fast as onshore.
The research also found significant differences between the North Sea regions, with the combination of more wind and rain in the northeast leading to accelerated erosion. In the northeastern part of the North Sea, where new wind farms are planned to be built starting in 2030, the protective coatings on the blades have about 20 per cent shorter lifetime than in the southwestern part, TNO says.
To obtain detailed data on wind and rain, the research project used new measurement methods, including disdrometers, sensors that measure raindrop size, which were used to analyse potential erosion and validate existing radar data.
Based on the research and weather simulations with a model developed by the company Whiffle, TNO and partners created an ‘erosion atlas’ that predicts where and when wind turbine blades will suffer damage from rain.
According to TNO and its research partners, having these new insights and the erosion atlas, and employing preventive measures can help the wind energy sector save millions of euros in maintenance.
“With this knowledge, wind farm operators can now proactively reduce turbine speeds to prevent severe damage, thereby lowering maintenance costs. By better predicting when turbine speeds need to be reduced, damage can be prevented more effectively”, said Van der Mijle Meijer .