Iowa-based electric utility MidAmerican Energy has idled nearly four dozen power-generating wind turbines after huge blades broke off of two turbines in recent weeks.
MidAmerican has paused the use of 46 turbines it has identified as having similar blades, which are about 177 feet long and weigh 18,000 pounds, the Des Moines Register reported.
The company acknowledged that one blade on a turbine near Paton fell on Oct. 15 into an empty field. In mid-September, another blade on a turbine near Adel crashed into a corn field. Similar incidents were reported in April and in October 2019 at Adair County wind farms. No one was hurt.
MidAmerican has isolated the issue to blades made by Danish manufacturer Vestas and is working with Vestas, MidAmerican spokesman Geoff Greenwood said in a statement.
In each case, data show lightning strikes occurred close to the turbines, MidAmerican said, with the blades in the earliest two failures taking direct hits. The failed blades all had the same lightning protection system, which is designed to channel the energy from any nearby strike safely into the ground, the company said.
“Though a blade failure remains an extremely rare occurrence, even one incident is not acceptable, which is why we’ve immediately enacted these additional precautions,” Greenwood said.
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