Dong Energy is to repair and upgrade all 273 blades at its six-year-old 209MW Horns Rev 2 offshore wind farm in Denmark.
The Danish company said it would be removing the components from 91 Siemens 2.3MW machines and bringing them to shore to tackle the “retrofit” work.
Repairs are centred on leading edge erosion and will be carried out following inspections of the individual blades.
Dong said wear and tear “is larger than expected” and most distinct at the tip of the blades where speeds of up to 280km per hour mix with water, sand and salt crystal.
“The blades have been designed to operate in the harsh environment of the North Sea but as it turns out the previous design has not been able to resist the weather, which has been more severe than initially expected,” said Dong.
Repairs consist of a new rubber coating developed by Siemens that is now standard for its offshore turbine fleet.
The manufacturer will also carry out the upgrade work on all the blades, a programme designed to increase production by between 1% and 1.5%.
Aerodynamic components known as Dinotails, Dinoshells and Vortex Generators will be installed to improve wind flows and wind capture by the equivalent of two extra 2.3MW machines.
Retrofit work will be based in Esbjerg and run from May this year through summer 2016. Horns Rev 2 is located around 30km off Jutland and has been in operation since 2008.