Iowa utility shuts down Vestas wind turbines

WINDSOR — An Iowa electrical utility that employs 3,000 wind turbines — 46 of them manufactured by Vestas Wind Systems A/S, the Danish wind-energy company with U.S. manufacturing plants in Windsor, Brighton and Pueblo, has shut down its Vestas towers while it diagnoses why blades have failed.

Geoff Greenwood, media-relations manager for MidAmerican Energy Co., based in Des Moines, told BizWest that a monitoring system on the company’s Beaver Creek wind farm in Greene County detected an issue with a turbine on Oct. 15. A technician investigated and found a blade separation; a piece of the broken blade was found in a harvested field. 

“This is the fourth blade failure we’ve experienced since last October and two in the past two months,” Greenwood said. “We have isolated the issue to certain Vestas blades that have sustained a direct or nearby lightning strike. We reviewed weather data and wind turbine monitoring data to identify all potentially affected blades. We have paused and are in the process of inspecting 46 Vestas turbines. If there is any damage to a blade, we will have it repaired or replaced, as necessary.”

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The towers are protected by lightning arrester equipment, which is intended to ground the energy from lightning strikes.

Greenwood said the utility is working with Vestas to help determine why the blades have failed and to replace as necessary. Vestas did not return BizWest’s requests for information.

“We operate more than 3,000 turbines, which translates to more than 9,000 blades. Since MidAmerican Energy first brought our first wind turbines online in Iowa in 2004, we have safely provided our customers with clean wind energy. Last year, the renewable energy we delivered to our Iowa customers on an annual basis exceeded 61%, and we continue to expand our wind energy capacity,” Greenwood said.

According to reports in the Des Moines Register, previous incidents involving Vestas blades included one in September from the Arbor Hills wind farm that fell into a cornfield in Adair County, and incidents in April 2020 and October 2019 at the Orient wind farm in Adair County. The blades are 175 feet in length. 

MidAmerican is a subsidiary of Berkshire Hathaway Inc.