March 1, 2005
Nina Pierpont, MD, PhD
A nacelle (generator and gearbox) weighing up to 60 tons atop a 265 ft. metal tower, equipped with 135 ft. blades, is a significant hazard to people, livestock, buildings, and traffic within a radius equal to the height of the structure (400 ft) and beyond. In Germany in 2003, in high storm winds, the brakes on a wind turbine failed and the blades spun out of control. A blade struck the tower and the entire nacelle flew off the tower. The blades and other parts landed as far as 1650 ft (0.31 mile) from the base of the tower. (Note that all turbines discussed in this article are “upwind,” three-bladed, industrial-sized turbines. “Downwind” turbines have not been built since the 1980s.) Given the date, this turbine was probably smaller than the ones proposed for current construction, and thus could not throw pieces as far. This distance is nearly identical to calculations of ice throw from turbines with 100 ft blades rotating 20 times per minute (1680 ft).