The Ice Issue

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Suddenly wind energy in cold climate is a hot topic. Several of the large manufacturers are now on the verge of offering de-icing systems.

Researchers in Finland started to investigate the possibility of de-icing wind turbines in the early 90’s. However, most manufacturers took little notice, as these issues were only considered relevant to a narrow and small niche market.

It wasn’t until a few years ago that the industry started looking at sites in cold regions. Then it dawned upon the developers that there were plenty of cold climate locations with excellent wind conditions.

Among the highlights during the first day at Winterwind 2012 was a stage presentation of de-icing solutions by six of the world’s leading manufacturers. Five of these systems are brand new and some have yet to enter the commercial market.

– Two years ago this session would have been unthinkable, the market just wasn’t there, says Göran Ronsten, program coordinator of Winterwind 2012.

Enercon’s de-icing system has been around the longest time. The company’s first commercial ice detection and de-icing system was installed in 2004. The system is based on hot air inside the blades.

Siemens (or Bonus, as the company was called before Siemens bought it) has been experimenting with blade de-icing since the middle of the 90′s. Two years ago Siemens Wind Power took the knowledge from the past and built it into a new blade de-icing system.

– The blade heating is integrated at factory, there’s no wiring on the outside of the blade, said Finn Daugaard Madsen, innovation manager at Siemens.

– That means there’s a low risk of transport damages, full retention of the aerodynamic profile and no effect on noise levels.

Today Siemens has 15 wind turbines with de-icing systems installed in four different locations in Sweden. About 70 new turbines with this system have been ordered.

Vestas is testing a new de-icing technology, and ice detection. Expected release for sales is 2012. The Danish world leader manufacturer of wind turbines is opting for the Enercon-solution: a system with hot air inside the blades.

– We didn’t pursue a leading edge system because of several reasons of which risk of damages due to lightning strikes was the most important, said Morten Sloth, product manager at Vestas Wind Systems, during his presentation.

According to Vestas the losses in energy production with leading edge heating was too large during summer compared to the gain during icing conditions. Operation and maintenance also proved to be too costly, as well as the system itself, said Morten Sloth:

– Costs of components and lightning protection were too high and we couldn’t guarantee a reasonable lifetime, he concluded.

German manufacturer Nordex has signed a frame work agreement with the municipally-owned utility Skellefteå Kraft to supply a total of 118 turbines  with a leading edge anti-icing system. The project concerned is “Blaiken”, which with 250 megawatts (MW) will be the largest wind farm in Sweden.

– Our anti-icing system can add 25 percent production during the icy season, said Lars Holm, senior vice-president of project development.

Finnish WinWind has been partnering with VTT research centre and has been carrying out tests with leading edge de-icing systems in cold climates since the early 1990’s (sub-megawatt and 1MW machines).

In 2008 WinWind received a contract with Skellefteå Kraft to deliver wind turbines to the Uljabuouda project and conduct a pilot project development of an ice prevention system.

– An important lesson so far is that the heating system can’t be too close to the lightning protection system, said Anders Sjögren from WinWind.

Indian-German Repower has chosen yet another path: the company put it’s faith into passive de-icing, special coating and other features that hopefully will keep ice off the blade.

– We will install over 500 cold climate turbines in the coming years, many in Canada. There’s no anti-icing solution that fits every situation, and if we develop an active system we can easily retro-fit it into our blades, said Kurt Stürken, managing director at Repower Systems Scandinavia.

Kurt Stürken also said that his company will have test turbines in Sweden next winter and a product ready for the market in 2014.

But whatever system the manufacturers choose to develop one thing is for certain, concluded Lars Holm:

– In the future anti-icing systems will become a must have in some regions.

Signals like that are already coming from the Swedish H&S Authority (Arbetsmiljöverket). Bel Bergenwall from the authority recently said that when de-icing systems are commercially available it won’t be legally possible for the potential owner to deselect such a safety feature in areas prone to icing.

– This implies big consequences, says Göran Ronsten: If you have no de-icing, you might not be able to sell.