For that reason, Taconite Ridge wind farm isn't producing as much electricity as Minnesota Power anticipated.
The $50 million project overlooks U.S. Steel's Minntac mine and covers about 450 acres.
This fall, inspectors with the turbine manufacturer discovered defects in several of the turbines' blades, and repairs have taken longer than anticipated, said Amy Rutledge, a spokeswoman for Minnesota Power.
"We had hoped they would be wrapped up by mid-December, but we've had a few issues with the weather," Rutledge said. Windy weather prevented the manufacturer from removing the rotors as quickly as they'd have liked, she said.
Repair crews for manufacturer Clipper Windpower hope all 10 turbines will be working by the end of January, Rutledge said. The delay won't affect Minnesota Power's electrical supply.
The defects, which aren't considered structural, are "wrinkles" in the fiberglass blades that must be fixed, said Taconite Ridge project manager Andrew Remus.
"If we leave them the way they are, without taking any action, they will affect the way the blade operates," Remus said. "The blade is all one piece, and you need it to be perfect."
Some of the blade wrinkles will be sanded down and re-laminated, Rutledge said. Others will get a patch a repair similar to using putty to repair a dented car, she said.
Taconite Ridge is the first large-scale wind farm in northern Minnesota. At full capacity, the turbines could produce 25 megawatts of electricity, which is enough to power 8,000 homes.
Minnesota Power is using the wind farm to increase its renewable energy resources and meet the requirements of a new state mandate for electrical utilities to produce 25 percent of their electricity from renewable sources by 2025.