BAD AXE – Crews are investigating how a 160-foot, 7-ton wind turbine blade broke, leaving it dangling like a shoelace and torqued around the structure.
The damaged blade is on one of DTE Energy’s 40 turbines in Sigel Township, near Section Line and Finkel roads. DTE says it happened at about 3:15 p.m. Friday. The access road to the turbine remains closed.
DTE Regional Manager Ron Chriss says DTE and Duke Energy were first on site and crews took immediate steps to secure the area. The utility says it noticed a turbine fault while monitoring from its Cass City location and got a call from a landowner.
“We will conduct a thorough root cause analysis once the blade is safe and secure and on the ground,” Chriss told county commissioners Tuesday.
“We will share the investigation results when they are available.”
Crews are investigating but haven’t determined a cause for the break, Chriss said. The utility is working with General Electric, the blade manufacturer, to finalize plans to safely remove the broken blade, he said, adding that GE is scheduled to arrive at the site this afternoon.
DTE expects an “extended outage” for the turbine during repairs and while “extensive top to bottom inspections of the entire turbine are conducted,” Chriss said.
“All protective zoning setbacks and wind turbine safety systems worked as designed during the Sigel 29 event,” he said. “That’s what we know as of now.”
DTE says the turbine automatically shut down after the incident.
Photos taken Monday show the blade broken in at least two spots. The blade, which DTE says is made of carbon fiber and fiberglass, twists overtop the turbine’s nacelle, pointing downward and hanging between two other blades intact.
In March 2013, a turbine blade, also in Sigel Township, broke because of a manufacturing defect, according to General Electric.
Lightning strikes have also jolted turbines: Dennis Buda, operations manager at DTE Energy who once called Huron County a “mecca for lightning,” said in August 2014 the utility had almost 17 blades that had been struck by lighting. In September 2013, a turbine near Minden City owned by Exelon Energy lost a blade after a lightning strike. Strikes in 2014 caused land and crop damage, forcing wind park owners to replace blades.
On Friday, the National Weather Service issued a special weather statement for southwest winds that could gust to 55 mph. Buda said turbines are programmed to automatically shut down and enter an idle state if winds blow 42 mph or more for a period of 15 minutes.
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