Cause of fallen wind turbine blade near Stuart under investigation

Officials from MidAmerican Energy spent Friday investigating how the blade of a wind turbine broke off and crashed into a corn field sometime Thursday or Friday in rural Adair County southwest of Stuart in Jefferson Township.

“The entire blade did not become separated, but a piece, a portion of the blade did fall off onto the ground,” said Geoff Greenwood, MidAmerican Energy spokesman said Friday.

The incident was reported by area farmers. The portion of the blade and the turbine it fell from sit on two neighboring properties.

The turbine from which the blade fell from is part of the Arbor Hills Wind Farm, which was put into service in late 2018. The wind turbine blades used in the Arbor Hills Wind Farm project span 177-feet each and weigh approximately 18,000 pounds. MidAmerican Energy has more than 3,300 wind turbines across Iowa, which equates to approximately 10,000 blades. Greenwood said, despite the number of turbines in Iowa, instances of blades breaking are “a very rare occurrence.”

“This has occurred approximately a half dozen times over the past five years,” Greenwood said. “That said, we don’t ever want it to happen and we are working with the manufacturer (Vestas) to determine a cause and we will do everything we can to ensure it doesn’t happen again. Safety is our number one priority.”

Greenwood said this is the sixth occurrence in which a MidAmerican turbine blade has broke and the causes of it is unknown at this time. In two previous instances, the blades were damaged by direct lightning.

“These are engineered very well for our weather conditions here in Iowa,” Greenwood said. “They are engineered for extreme weather conditions. We did not sustain any significant wind farm damage from the recent derecho. These are highly engineered wind turbines and we are confident in their performance. We are certainly wanting to know what occurred here.”

This is a developing story.