As wind farms age, owners look to 'repower' them with new blades

The Ashtabula Wind Energy Center north of Valley City, N.D.

BISMARCK — The owner of a wind farm in Barnes County wants to “repower” the turbines with new blades and gearboxes that will increase the amount of electricity produced at the facility, a process that’s expected to become more common across the state as wind farms age.

The Ashtabula I Wind Energy Center near Valley City was built in 2008 with a capacity to generate 148.5 megawatts of power. Installing the new equipment would boost the capacity to 160.4 megawatts.

Ashtabula Wind, a subsidiary of NextEra Energy, is seeking approval from the North Dakota Public Service Commission, which discussed the matter at a meeting Thursday, Nov. 7.

Commissioner Julie Fedorchak said she believes repowering wind farms will be the “new normal” in the years ahead as companies look to replace older parts with newer, more efficient ones and take advantage of federal tax credits.

“This will probably be the first of many that we see,” she said.

Blades tend to last 10-15 years, Commissioner Brian Kroshus said.

“The fiberglass breaks down over time,” he said. “Dust particles in the air hitting the blades as they’re spinning begins to compromise the integrity of the blade.”

Windy states are grappling with how to dispose of the blades, which can range in size from 100-300 feet. More than 5,100 blades sit atop wind turbines in North Dakota.

Diana Trussell, solid waste program manager with the North Dakota Department of Environmental Quality, said in an interview that at least two landfills in the state have accepted blades.

“They are requiring them to cut the blades down to more manageable lengths,” she said. “That way, it is easier to bury them or crush in the landfill.”

Not all facilities have the necessary space, equipment or personnel to take them in.

It’s unclear where the existing blades attached to the 99 turbines at the Ashtabula wind farm would end up. The company did not say in documents filed with the PSC, and it did not immediately respond to a request for comment.

Ashtabula Wind plans to complete the upgrades over a three-month period, according to a memo from an engineering firm contracted by the company.

The commission did not take any action on the proposal Thursday, opting instead to discuss the matter further at a work session slated for Nov. 26.

Commissioner Randy Christmann requested the work session because the order the PSC had prepared to grant on Thursday does not specify a maximum capacity for the wind farm, despite statements from Ashtabula Wind that it will be 160.4 megawatts.

He expressed concern about transmission problems caused by potential advancements in wind technology down the road that could result in turbines with individual capacities far beyond what’s common today.

“Fifteen years ago, I didn’t imagine we could ever have 3-megawatt turbines out here,” he said. “In another decade, are we going to have 6- or 8- or 10-megawatt turbines?”

A flurry of new wind, solar and natural gas power plants are causing congestion on the electric grid in the Midwest. Some projects are prompting expensive upgrades needed on power lines and other transmission infrastructure.

Christmann acknowledged that the relatively small overall increase of 12 megawatts at the Ashtabula wind farm would not result in major problems, but he said a more substantial jump down the road “could cause huge congestion issues.”

Fedorchak said she also has concerns about the lack of a limit on the capacity of the facility, but she felt the commission could not impose one due to a change in state law several years ago affecting the permitting process for energy facilities making upgrades within their existing footprints.

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