Robust managementt for rust: Offshore wind turbines

In rough sea and air, offshore wind turbines require significant, and costly maintenance. But the rust gnaws at them. To pay off the equipment, they should at least be in operation for 25 Years - which is possible only with elaborate maintenance. In order to ensure a successful operative future, more cost-effective maintenance measures are needed including innovative materials and technologies. Fraunhofer researchers are developing a protective film that will optimize the repair process and help drive the develop of needed criteria for the inspection.

In the Baltic and North Seas alone, a number of new offshore facilities are planned. Here the maintanance and repair are a tricky business - the turbines can not be towed as a production platform into a dry dock for maintenance. All work must be carried out in all weathers at sea. The application of protective coatings against corrosion makes maintenance difficult. 

Researchers are currently working on the joint project "RepaKorr". "The goal is to develop a holistic and sustainable approach to maintenance and repair of protective systems, in order to simplify the process technically and to reduce costs," said Peter Plage of the Fraunhofer Institute for Manufacturing Technology and Applied Materials Research IFAM in Bremen. By March 2016, the comprehensive inspection and repair plan will be available for corrosion protection systems for offshore wind turbines. Particular attention will be paid to those parts of the wind turbines that are not permanently under water and therefore require a robust rust protection through coatings. 

Therefore, development of repair materials by the Sika Germany GmbH and the novel application and assessment of procedures by Muehlhan AG are at the center of the project. New inspection concepts are also being worked out because the relevant rules and methods do not consider the case of repair. In addition, "standards are essential in order to establish that a repair is successful," says Plagemann. But so far there is no such thing. Researchers at the IFAM have developed criteria. 

The project partners AirRobot GmbH are exploring ways to work with drones to inspect coatings and determine whether repairs are needed. Clear inspection criteria are also needed to automate this process as much as possible. So far, having to search the equipment is time consuming and risky for workers. 

Protective film with high adhesion 

Researchers at the IFAM have developed a protective film, to ensure surfaces are protected from moisture and salt until the repair coating can be applied. "The challenge is that the film must have a high adhesive strength, but at the same time be simple to remove without leaving a residue. 

Reduce repair costs 

"This protective film can make the repair process more cost-effective because you can plan the critical period between surface preparation and coating application much better," Plagemann describes the effect. This is an essential factor for the maintenance and repair costs of offshore wind turbines which can add up over the years to one hundred times the costs for new construction. While a metal coating in the construction of onshore wind facilities can cost 20 to 30 euros per square meter, the cost for offshore plants can be several thousand euros. These costs must be reduced significantly. 

(Translation from German to English with the help of Google Translate)