Blade breaks off wind tower near Wyanet

A wind turbine blade came crashing to the ground Wednesday, halting energy production at a small-scale wind farm southwest of Wyanet because of what may be a defective design.

In all, four turbines on Richard Shertz's property - all part of the AgriWind facility in central Bureau County - have stopped turning after a blade on top of one of the towers broke off about 9:30 a.m.

"It was the loudest noise I've ever heard," he said. "I thought it was thunder."

It wasn't until about noon that Schertz went outside and saw that the blade on one of the turbines had broken off near its base. The blades are 140 feet long and 15 feet wide at their widest point.

Officials from Suzlon Wind Energy, the turbine manufacturer, arrived at the property later in the day and found the blade 100 to 150 feet away from the structure. No one was hurt when the blade came down and landed in an adjacent cornfield.

The turbines were installed in May or June of 2007, according to Schertz. One of the turbines has been off all summer because its blades had cracks in them, he said.

A Suzlon company representative said the blades on all four turbines were scheduled to be replaced next week.

The representative also said the point at which the blade separated from the stem is a spot where cracks have been found on other blades. The cracks are the result of a design issue, and the company is currently retro fitting blades throughout the country.

Company representatives will be out at the Schertz farm through the weekend to investigate and analyze what happened.

"We are naturally quite concerned," said the representative, who agreed to be quoted but asked not to be identified because of company policy. "Safety is very important to us."

Christine Real de Azua, assistant director of communications for the American Wind Energy Association, said turbine failures of this magnitude are "relatively rare occurrences."

Though the association doesn't track the number of times turbine blades break or, in more extreme cases, when entire towers collapse, Real de Azua said she knows of only a handful of such circumstances within the last year out of the 25,000 to 30,000 turbines operating in the country.

Turbines are built to withstand the very elements that help them generate power, but contain complex machinery that can succumb to those forces, she added.

"Generally, given the operating conditions . . . you'll find there are very few failures," Real de Azua said. "There's no question they're reliable and safe."