August 9, 2014
Michigan

Lightning strikes again: DTE wind turbines damaged by ‘Mother Nature’

By Chris Aldridge, Tribune Staff Writer | Huron Daily Tribune | August 8, 2014 | www.michigansthumb.com

“We have almost 17 blades that have been struck by lightning since we started,” said Dennis Buda, operations manager at DTE.

Buda said lightning has struck 11 to 12 turbine blades owned by DTE in the Thumb area, while another five have been jolted at the utility’s Echo Wind Park, grounded mostly in Oliver and Chandler townships.

Add that to three more strikes that Buda said occurred this week – one at a turbine in Sebewaing and two at Echo.

The damages from lightning strikes have forced wind park owners to replace blades, which rotate on towers that reach more than 300 feet in height. For DTE, a turbine in Sigel Township required a single blade exchange last month, Buda said.

Damages to land area in Sigel Township have been restored, but the strikes also brought crop damages, Buda said. DTE plans to pay landowners for those damages.

“We met with both individuals and looked at the areas,” Buda said. “They’re both very, very happy with the way the sites were restored.”

Buda said DTE is working closely with General Electric, the country’s largest manufacturer of wind turbine parts and supplier for the majority of turbines in the Thumb, to determine root causes for the strikes.

“We have shipped those blades to a lab just outside of Boston for review,” he said.

The theory is that the turbines are well-insulated, Buda said, with the blade’s metal tip wrapped in copper that acts as a lightning rod to the ground.

Buda said a resident on Section Line Road near turbines in Sigel Township had a problem with what’s known as the phenomenon of shadow flicker, caused by churning turbine blades creating shadows and reflections.

“He contacted the county, county contacted us and we worked with (the resident) on turning off that turbine remotely on areas as the sun rose,” Buda said.

The turbine had been shut off from 6 a.m. to 7 a.m. for a couple weeks, and then shut-off time was shortened to a half-hour window, he said.

“Now the arc of the sun is out of the flicker range, and (the resident) can enjoy his coffee in the morning without being shadowed,” Buda said.

Other issues also have plagued GE-supplied turbines and blades at DTE wind parks.

Last year, a blade in Sigel Township failed because of a manufacturer’s defect due to uneven heating conditions at a production plant in Brazil, Buda said at a March 2013 county meeting. GE manufactured the blades.

A broken carbon fiber blade was found at DTE’s Echo Wind Park in November last year. GE said the cause was a manufacturing anomaly.

Buda said a gearbox failure on a turbine in Sigel Township was discovered during annual inspection in April.

“We exchanged that gearbox under GE warranty and that was completed mid-July,” he said.

Bob Judge, communications manager for Exelon Power, said Exelon is taking precautions for lightning, but that a strike in late September last year at Michigan Wind II in Minden Township was a rare occurrence.

At a planning commission meeting last month, member Jeffery Krohn said there were about nine lightning strikes at turbines in the Harvest Wind I park in southern Huron County during its first summer of operation.