Willmar, Minn., wind turbines may be nearing end of their useful life
With the original manufacturer no longer in existence, it is becoming more and more difficult for Willmar Municipal Utilities to find replacement parts for its aging wind turbines.
WILLMAR, Minn. — Willmar, Minnesota’s wind turbines, constructed and put into operation in 2009, may be close to the end of their useful lifespan to generate power for the city.
The lifetime expectancy for the turbines was estimated to be 20 years when constructed. However, it is becoming increasingly difficult to find replacement parts needed for the DeWind 8.2 turbines, according to Willmar Municipal Utilities Maintenance and Utilities Supervisor Kevin Marti.
Since construction, DeWind has gone out of business and other companies from which Willmar Municipal Utilities has historically been able to obtain parts are no longer able to supply them, Marti told the Municipal Utilities Commission at its Nov. 14 meeting. DeWind founded in 1995 was eventually sold in 2009 to Daewoo Shipbuilding and Marine Engineering of South Korea. The company later entered liquidation in 2015 and was deleted from the German Trade Register in December 2017, according to the company's page on Wikipedia.
This became evident recently when trying to obtain replacement breakers for both turbines. The usual vendors no longer supply them, and Willmar Municipal Utilities finally reached Schneider Electric, the company that originally made the breakers.
“They sent an engineer out finally and were able to determine that they still can make these units,” Marti said.
The breakers were ordered, but they come from Germany and are expected to take nine to 12 weeks to arrive after the order "gets in the queue."
Marti explained to the commission that the wind turbines are "incredibly unique pieces of equipment with hundreds of components just like this that can take the turbine down, and, for the most part, they are very unique in the fact that the company no longer exists. It’s really challenging to find new parts. We’ve been lucky so far, but at some point we’re going to run into some widget or something that takes these things out.”
He said it could be a $10 part that's no longer available, or a $200,000 part, that finally takes out the wind turbines.
“I just want to be upfront and honest about the turbines,” he continued, noting Willmar Municipal Utilities is currently in its 13th year of the expected 20-year lifespan of the turbines and the new breakers should last through the 16- to 18-year range.
“We’ll have to determine probably in the (next) two and a half, three years as we watch those breaker counts, about ordering another set barring any other problem,” he said.
Despite one of the two turbines not being up to speed during the last month, the kilowatt-hour output for the month was “pretty decent,” according to Marti, producing 616,414 kilowatt-hours. “If they had both been up and healthy, it would have been a stellar month.”
Over the five-year average, that generation of power landed right in the middle of what is expected.
For the year, the turbines have generated 6,546,163 kilowatt-hours of power, which is “knocking on the door of catching 2020” — one of Willmar Municipal Utilities' best years for wind power generation.
“We still expect to have a very good year overall over the next month here, we’ll keep watching that,” Marti said.
Commissioner Cole Erickson asked if the situation is unique or if it is an industry-wide issue.
“We’re alone, I would say, because of the manufacturer that no longer exists,” Marti responded. “We know of one other 8.2 — the same model of wind turbine that we have — that is still in operation and that’s it in the United States. There may be some 8.2s in South America, Argentina, that are still operational, but we can’t confirm that. So, you are one of three in the world that I can say today are still operational.”
Commissioner Shawn Mueske noted the fact that Willmar Municipal Utilities has been able to maintain the turbines for which the manufacturer no longer exists “is a great testament to our staff and your leadership.”
He then asked when Willmar Municipal Utilities may hit the threshold for which it is no longer feasible to keep the turbines operational.
“In layman's terms, off the top of my head, a major component that would require you to bring in a crane, for example, in my opinion, would be the death of the turbine because of the remaining years that you have left to offset that repair,” Marti said. “If you needed, for example, a gear box and it cost you upwards of $300,000-$400,000, they don’t make those anymore, so they’d have to reconfigure the tower to fit the gear box and take the blades off and bring the things to the ground.”
That cost would ultimately exceed the remaining useful life of the turbine and deem the repair unfeasible.
The breaker units which need to be replaced are approximately $40,000 each and Willmar Municipal Utilities feels confident they will extend the life of the turbines another three to four years.
A breaker in each turbine is tripped every time the turbine starts or stops, he explained. Rated for about 8,000 to 9,000 trips in their lifespan, the current breakers have more than 10,000 trips on them.
Marti told the commissioners that Willmar Municipal Utilities is exploring its options with the turbines and will bring more information to the commission's planning committee.
One option could be taking the turbines off, stripping everything out of them and repowering with a new unit that will reuse the tube, he explained.
General Manager John Harren told commissioners last year that the turbines were costing about 3 cents per kilowatt to operate. When looking at expenditures, Willmar Municipal Utilities looks at how that will change its kilowatt cost on an annual basis in relation to other resources.
“So once we start pushing that threshold of breaking even or maybe slightly going beyond that break-even, we’ll be in front of our commission having that discussion,” he told the members.