Given that the sterotypical image of the world's northern regions involves howling winds, why don't we see more wind turbines in such places? Well, it's largely because those turbines' blades would ice up a lot. The added weight could cause them to turn more slowly, to break down by throwing off their balance, and it could cause their operators to shut them down during potentially icy weather. The European Union Windheat Project is aiming to change that, with a carbon nanotube-based de-icing system.
While airplane-style de-icing systems could be used, these typically heat up the entire surface that needs to be kept ice-free – regardless of which parts of that surface are actually experiencing icing. That uses more power than necessary, which is not what you want on a system that's designed to generate power.
The Windheat system instead divides the blade into a number of separate zones, each one of which is covered with its own section of self-adhesive polymer film. That film has been sprayed with a very thin layer of carbon nanotubes, which has then received a protective clear coating. Each zone also contains its own tiny ice sensor, which monitors fluctuations in temperature and humidity on the film's surface.
When ice formation is detected (usually on the leading edges of the blades), an electrical current is instantaneously applied to the nanotube layer in that area. This causes the film to heat up, melting the ice within seconds. As soon as the ice is gone, however, the heating ceases.
Researchers at the Fraunhofer Institute for Manufacturing Engineering and Automation, which is one of the seven Windheat partner groups, have already tested the technology on small turbines within a wind tunnel. They believe that it could easily be scaled up for use on full-size turbines.
The Windheat Project began in 2013, and is due for completion next year. Its aim is to increase the overall energy efficiency of wind turbines in cold climates by at least 18 percent.
Sources: Fraunhofer, Windheat