After a deadly tornado devastated the US state of Iowa, destroying 10 wind turbines, social media posts raised doubts about the reliability of this type of energy in locations prone to extreme weather events. But only a small portion of turbines in the Midwestern state were affected, and officials and an engineer told AFP such intense damage is rare.
“This is what tornadoes do to wind turbines,” says a May 23, 2024, Facebook post with a link to a video of a wind turbine being snapped in half during a tornado that killed at least five people in Iowa.
Similar claims question why a location prone to tornadoes would support wind farms spread across here, here and here while residents were investigating injury in Adair and Adams counties.
Iowa is heavily dependent on renewable energy and is the second largest producer of wind energy in the United States after the state of Texas (archived here).
Tornadoes are impacting the state, and local media reported that the May 21 storm destroyed ten wind turbines (archived here and here), but experts said this level of damage is atypical.
“For the record, that’s 10 of the 6,757 turbines in the state, according to the Energy Information Administration,” said Kanan Kappelman, a spokeswoman for the Iowa Economic Development Authority.
“It is unusual for wind turbines to suffer tornado damage,” she told AFP on May 23.
MidAmerican Energy, which has operated in the state since 2004, also said this storm caused an “unprecedented impact” on its wind fleet.
“We have only experienced one other case of a wind turbine collapse, which was also caused by a tornado,” Tina Hoffman, a company spokeswoman, told AFP on May 24.
Video footage of turbines withstanding tornadoes has also been captured (archived here).
Strong winds
Tornadoes are measured on the Enhanced Fujita Scale or EF Scale and rated based on wind speeds and damage (archived here).
The National Weather Service said it confirmed “EF-4 damage in Greenfield, Iowa, EF-3 damage in NW Adams County and EF-2 damage from two tornadoes: at Polk in Story County and near Arbor Hill” (here archived). Top wind speeds in the EF-4 tornado were estimated at 175-185 miles (281.6-297.7 kilometers) per hour.
Manufacturers design wind turbines to withstand extreme weather, including severe thunderstorms and high winds, but Hoffman said, “Few structures can withstand a direct hit by a powerful tornado, like we experienced on Tuesday.”
She said several of the company’s turbine sensors recorded wind speeds of more than 100 miles per hour as the tornado approached, before the towers were destroyed.
Sanjay Raja Arwade (archived here), a civil engineering professor at the University of Massachusetts Amherst, told AFP that the chance of a tornado directly hitting a tower is very high. low.
“TThe amount of land area affected by a given tornado impact is relatively small,” he said on May 24.
Turbine operators also take precautions, such as designing the systems to automatically shut down at very high wind speeds (archived here).
Iowa law requires wind turbines to be located a minimum distance from populated areas to reduce the risk to human safety in the event of a catastrophic event (archived here).
But turbines “like any other piece of infrastructure, including buildings, can be damaged by a direct hit by a tornado,” an Energy Ministry spokesperson told AFP on May 23.
By the end of April, tornado reports in the United States had already largely surpassed the 1991-2020 annual average, setting the stage for one of the most active years on record (archived here).
But Arwade said, “If you look at all the wind turbines in Texas, Oklahoma, Nebraska, Iowa and all the Great Plains states, the number of turbines that will be affected in any given tornado season is small. Even if we consider the effects of climate change take it with you, it will remain small.”
AFP has debunked other claims about wind turbines, here and here.
