The world's largest producer of wind turbines, and the whole idea of large-scale wind energy itself, suffered a setback this summer with news that all the turbines at Denmark's Horns Rev (Reef)—the biggest offshore wind farm built to date—would be moved to shore for repair and replacement of defective transformers and generators. Vestas Wind System A/S in Ringkøbing blamed harsh sea conditions for the substandard performance of equipment supplied by ABB Ltd., the Swedish-Swiss energy conglomerate headquartered in Zurich. The generator and transformer problems made it necessary to retrofit all 81 of the 2-megawatt turbines, at considerable expense.

Vestas, the world's leading wind technology supplier, installed the Horns Rev turbines in 2002, under contract with Denmark's biggest power producer, Elsam A/S in Fredericia [see photo, "Let It Blow"]. The mishap at Horns Rev is especially embarrassing because similar problems arose at the first big wind farm Vestas installed, near Copenhagen. The company had expressed confidence when erecting the Horns Rev turbines that this time things would go more smoothly.

Yet to judge from IEEE Spectrum's reporting and observations in Denmark during late August and early September, Denmark's commitment to wind, which now supplies about 20 percent of its electricity, is unshaken. Its wind program is a point of national pride, and the manufacture of wind turbines, in this country of some 6 million people, now has a weight comparable to that of auto industries in much larger countries.

But Denmark's wind program has come under increasingly sharp criticism in places where the planned construction of wind farms is arousing the ire of residents determined to preserve landscapes and vistas. Go, for example, to the Web site maintained by Save Our Sound—an organization dedicated to blocking construction of a large wind farm in Nantucket Sound, off Cape Cod in Massachusetts. There you'll find elaborately reasoned and documented arguments denouncing Denmark's whole wind effort.

Especially controversial are the subsidies made to Danish wind power and problems connected with grid management. It's pretty universally accepted among wind specialists that keeping the transmission system running smoothly gets tougher as wind power's share grows. This happens for a wide variety of reasons having to do both with the wind's variability and special difficulties with voltage support when power from wind is carried over long distances.

Two years ago, when Spectrum featured the Horns Rev project [see "Reap the Wild Wind," October 2002], Peter Christiansen, a senior engineer with Elsam Engineering A/S, conceded that grid stability problems were serious. Contacted in September, he says nothing has happened in the meantime to change his mind.

John Eli Nielson, a senior engineer with Eltra, the organization that manages the grid in western Denmark, said that Eltra has launched an ambitious program of breaking the country's whole western grid into virtually autonomous cells. The objective is for each cell to be able to provide adequate voltage support (reactive power) to meet its own needs and to be able to restore power independently after an emergency shutdown ("blackstart").

Only Vestas CEO Svend Sigaard can comment on the unfortunate situation at Horns Rev, but he deflected all requests for an interview.

Perhaps, from Vestas's point of view, the less said, the better. True, its stock has held up well this year, and its business was up 25 percent in the first half compared with the previous year. But Vestas is facing increasingly sharp competition from a dangerous rival. General Electric Co., in Stamford, Conn., recently emerged as the world's second leading turbine supplier, having acquired Enron's wind unit and merged it into its potent Energy Systems Division, based in Atlanta. GE does not play second fiddle for long, if it can help it.