Ten Vestas turbines destroyed as deadly tornadoes hit US wind farms
Berkshire Hathaway-owned MidAmerican confirmed machines downed at Iowa plants
Wind farms in the Midwestern US state of Iowa took direct hits from a spate of tornadoes, destroying at least six turbines owned by utility MidAmerican Energy and several others.
Five wind turbines at MidAmerican's Orient wind farm and one at its Arbor Hill wind farm, were impacted. Four more at the Prescott wind farm, owned by RPM Access, were also destroyed by tornadoes that swept through the region around 4pm local time on Tuesday.
MidAmerican's wind farms are in Adair County, around 60 miles (97km) west of Des Moines, while Prescott is in neighbouring Adams County. Damage was severe across the region and at least four deaths have been reported.
“Several turbines registered wind speeds over 100 mph (160 km/h) as the tornado approached, before we lost contact with our sensors and the turbines were destroyed,” said Tina Hoffman, vice president for corporate communications for MidAmerican, a Berkshire Hathaway-owned utility.
“Based on several video clips posted on social media, it appears tornadoes in Adair County directly struck our wind turbines,” she added.
The Midwest of the US is known as “tornado alley” for the frequency of the fierce storms, but Hoffman noted that impacts on wind farms is rare, calling the devastation “unprecedented”.
Since beginning operations in Iowa in 2004, “we have experienced only one other instance of a wind turbine collapse, which was also caused by a tornado,” she said.
Technicians operating at the sites escaped to a storm shelter at the operations and maintenance facility where they safely rode out the disaster.
Hoffman said that while turbine OEM design wind turbines to withstand Iowa's ever-changing weather conditions, including severe thunderstorms and high wind events, “but, as we've seen from the damage sustained throughout several Iowa counties, few structures can withstand a direct hit by a powerful tornado”.
She also confirmed that the company is inspecting all of its wind facilities in storm-affected areas “out of an abundance of caution”.
“We are continuing to assess damage to our facilities in the area and are working with our turbine manufacturers on our next steps forward,” she said.
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