Feb 2 2016
Renewable energy is produced from the winds out at sea by offshore wind farms. The saltiness in the air causes the wind turbines to rust. For these farms to be profitable, the turbines need to remain in action for 25 years at least, which would not possible without regular maintenance. A team of researchers from Fraunhofer have created a protective film, which will enhance the repair method. They are also looking to formulate an essential inspection criteria.
Carrying out repairs on an offshore wind farm. (©Photo: Muehlhan AG)
Energy evolution is happening at a greater speed than ever before, with a number of wind parks being constructed in marine regions e.g., the Baltic Ocean and North Sea. Structure maintenance and repairing is challenging, one issue being that these structures cannot be transported to a dry dock for maintenance like a floating oil platform, as they are anchored in the seabed. All of these activities have to be performed out at sea regardless of the weather conditions. The task becomes even more complicated when corrosion-resistant coatings have to be renewed. As part of the collaborative RepaKorr project, a number of innovative solutions are being developed, which will ease the tasks in the future.
Our aim is to develop a holistic, sustainable concept for the maintenance and repair of protective systems, that will be simpler to apply and thereby reduce costs.
Peter Plagemann, Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM)
Implementation of the complete inspection and repair solution, to optimize the corrosion resistance of the offshore wind farms is set for March 2016. It takes into special consideration the wind turbine components that are not permanently under water, and provides a specifically hard-wearing coating to prevent rust formation.
Sika Deutschland GmbH and Muehlhan AG are two key contributors to the project, and are creating new repair materials, and unique application and analysis techniques. Their efforts are complemented by the progress of new testing concepts, as existing guidelines and techniques are not adapted to the evaluation of repaired parts.
There is a need for standard procedures that can be used to verify the quality of repairs.
Peter Plagemann, Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM)
As there are no guidelines at the moment, the IFAM researchers have formulated tests according to their own criteria.
AirRobot GmbH, another project partner, plan to inspect coatings using drones and establish the types of repairs required. In order for this technique to be automated, clear inspection criteria should be in place.
Protective Film with High Adhesive Strength
The IFAM team’s protective film will prevent the surfaces from exposure to salt and moisture. These surfaces have been cleaned and prepared for recoating until actual repair coating will be 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.
Peter Plagemann, Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM)
The researchers are testing out two ideas - one has been successful evaluated in the laboratory, and the other is awaiting a patent.
Lower Repair Costs
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.
Peter Plagemann, Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM)
This is an important aspect, as repairing and maintaining offshore wind turbine costs can easily increase to a 100 times the original cost of construction over the span of operation. For example, metallic coating of onshore plants in general, costs about 20 to 30 euros per square meter, while the cost can increase to thousands of euros for offshore plants. One of the goals of the RepaKorr project is to significantly decrease these costs.
The project partners plan on standardizing the inspection techniques, computerizing the results of each intervention, and transmitting these data into current electronic, online monitoring systems. This will assist in the reduction of inspection and repair cycles by facilitating accurate and targeted planning.