Tornado Pummels Wind Turbines in Iowa

The footage from southwest Iowa is shocking: In the trail of a tornado, a wind turbine is bent in half like a cheap straw, its hub engulfed in flames and thick black smoke, its blades on the ground.

“You’re seeing multiple of these big wind turbine towers that have been destroyed,” Zane Satre, a meteorologist for KCCI 8 News in Des Moines, told viewers. “These are big tall ones — I think they’re what, like 250 feet tall? Well that tornado took them out.”

But it’s rare for tornadoes or other types of severe weather to destroy a wind turbine, said Fraser McLachlan, chief executive of GCube, a company that insures renewable energy projects like wind farms and solar arrays.

Turbines are now built to withstand events like tornadoes, hurricanes and typhoons because of advances in technology since the early designs of the 1990s. They have built-in mechanisms to lock and feather the blades, changing their angles, when winds reach 55 miles per hour. That reduces the surface area of the blades pointed toward the wind.

“You will lose a blade here or a blade there,” during windstorms, Mr. McLachlan said. But a complete knockout is unusual, he said.