The Dangers of Wind Power

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The story reports the disastrous results of a questionnaire passed out to members of the German WindEnergy Association asking them to rank manufacturers. Only Enercon, based in Germany, managed a ranking of "good." The company produces wind turbines without gearboxes, eliminating one of the weakest links in the chain.

Even among insurers, who raced into the new market in the 1990s, wind power is now considered a risky sector. Industry giant Allianz was faced with around a thousand damage claims in 2006 alone. Jan Pohl, who works for Allianz in Munich, has calculated that on average "an operator has to expect damage to his facility every four years, not including malfunctions and uninsured breakdowns."

Many insurance companies have learned their lessons and are now writing maintenance requirements—requiring wind farmers to replace vulnerable components such as gearboxes every five years—directly into their contracts. But a gearbox replacement can cost up to 10 percent of the original construction price tag, enough to cut deep into anticipated profits. Indeed, many investors may be in for a nasty surprise. "Between 3,000 and 4,000 older facilities are currently due for new insurance policies," says Holger Martsfeld, head of technical insurance at Germany's leading wind turbine insurer Gothaer. "We know that many of these facilities have flaws."

Flaws And Dangers

And the technical hitches are not without their dangers. For example:

• In December of last year, fragments of a broken rotor blade landed on a road shortly before rush hour traffic near the city of Trier

• Two wind turbines caught fire near Osnabrück and in the Havelland region in January. The firefighters could only watch: Their ladders were not tall enough to reach the burning casings

• The same month, a 70-meter (230-foot) tall wind turbine folded in half in Schleswig-Holstein—right next to a highway

• The rotor blades of a wind turbine in Brandenburg ripped off at a height of 100 meters (328 feet). Fragments of the rotors stuck into a grain field near a road.

At the Allianz Technology Center (AZT) in Munich, the bits and pieces from wind turbine meltdowns are closely examined. "The force that comes to bear on the rotors is much greater than originally expected," says AZT evaluator Erwin Bauer. Wind speed is simply not consistent enough, he points out. "There are gusts and direction changes all the time," he says.

But instead of working to create more efficient technology, many manufacturers have simply elected to build even larger rotor blades, Bauer adds. "Large machines may have great capacity, but the strains they are subject to are even harder to control," he says.

Even the technically basic concrete foundations are suffering from those strains. Vibrations and load changes cause fractures, water seeps into the cracks, and the rebar begins to rust. Repairs are difficult. "You can't look inside concrete," says Marc Gutermann, a professor for experimental statics in Bremen. "It's no use just closing the cracks from above."

The engineering expert suspects construction errors are to blame. "The facilities keep getting bigger," he says, "but the diameter of the masts has to remain the same because otherwise they would be too big to transport on the roadways."

Not Sufficiently Resilient

Still the wind power business is focusing on replacing smaller facilities with ever larger ones. With all the best sites already taken, boosting size is one of the few ways left to boost output. On land at least. So far, there are no offshore wind parks in German waters, a situation that Minister Gabriel hopes to change. He wants offshore wind farms to produce a total of 25,000 megawatts by 2030.

Perhaps by then, the lessons learned on land will ward off disaster at sea. Many constructors of such offshore facilities in other countries have run into difficulties. Danish company and world market leader Vestas, for example, had to remove the turbines from an entire wind park along Denmark's western coast in 2004 because the turbines were not sufficiently resilient to withstand the local sea and weather conditions. Similar problems were encountered off the British coast in 2005.

German wind turbine giant Enercon, for its part, considers the risks associated with offshore wind power generation too great, says Enercon spokesman Andreas Düser says. While the growth potential is tempting, he says, the company does not want to lose its good standing on the high seas.

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