German researchers gathered around the RepaKorr collaborative project are developing an all-round inspection and repair solution to increase the corrosion resistance of offshore wind farms, according to Fraunhofer, one of the participants in the project.
The new solution, which includes the development of a special anti-corrosive film, is expected to be ready for implementation by March 2016. It places special emphasis on those parts of a wind turbine that are not permanently submerged under water, and therefore need a particularly hard-wearing coating to prevent the formation of rust.
The researchers at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Bremen are developing the protective film to prevent moisture and salt from coming into contact with surfaces that have been cleaned and prepared for re-coating until such time as the actual repair coating is applied.
“The challenge is that the film must adhere firmly and yet be easy to remove without leaving any residue. We’re trying to find a solution that combines these seemingly contradictory requirements,” said Peter Plagemann of IFAM.
“The positive effect of this protective film is that it allows the repair process to be carried out more cost-effectively, because the critical period between preparing the surface and applying the coating can be planned much more reliably.”
The cost of maintaining and repairing offshore wind farms can easily add up to one hundred times the original construction cost over the years of operation, Fraunhofer said. Whereas the metallic coating of onshore plants generally costs around EUR 20 to 30 per square meter, the price can rise to several thousand euros for offshore plants. The RepaKorr project aims to considerably reduce these costs.
The main contributors to the project are Sika Deutschland GmbH, which is developing new repair materials, and Muehlhan AG, which is developing novel application and analysis methods.
This work is being complemented by the development of new testing concepts, as current guidelines and methods are not adapted to the testing of repaired components.
“There is a need for standard procedures that can be used to verify the quality of repairs,” said Plagemann.
”Because such guidelines do not exist at present, the IFAM researchers have devised tests based on their own criteria.”
The project partners intend to standardize the inspection process, computerize the results of individual interventions, and feed these data into existing electronic, online monitoring systems. This will help to shorten inspection and repair cycles by enabling more precise, targeted planning.
Another project partner, AirRobot GmbH, is investigating the idea of using drones to inspect coatings and determine what repairs are needed. Here, too, clear inspection criteria must be defined so that this process can be automated as far as possible. Until now, this job has been done by workers wearing climbing harnesses – a time-consuming and dangerous activity.