This video depicts the catastrophic failure of a wind turbine in Denmark in mid-February. Press coverage of the event, one of two turbine failures within a week in Denmark, can be found at http://jp.dk/uknews/article1277616.ece . The turbine shown is an older model, without the same level of fault detection and computer control systems as modern, larger machines. The cause is not stated in the news article, but if a turbine's braking system fails or is disengaged due to human error, the turbine can go into an "overspeed" condition that, depending on conditions, may result in its destruction.

According to the National Renewable Energy Laboratory's Chief Engineer, "Modern wind turbines rely on three independently controlled pitch systems. Any one [of those systems] can save the machine from a [runaway] like that. They have their own battery supply systems, fault detection system and internal diagnostics. The master controller monitors all the subordinate control systems (back brake, lubrication system, yaw drive, anemometers, power system, as well as the pitch system). If any one of the sensors behaves abnormally it creates a fault and the machine shuts down."

The wind is perhaps the most variable energy source, with changes in direction and force that can occur quickly, and it's a very challenging engineering and operating environment. In the wind industry's early days 25-30 years ago, turbine failures were very common and many early turbine manufacturers went out of business. Over time, machine designs improved in both durability and productivity, and today failures among the more than 100,000 wind turbines operating worldwide are generally quite rare.

Even so, as the video indicates, turbines do sometimes fail, due to mechanical or human error. Turbine failure can be dangerous to workers, so the wind industry has a very strong and real reason to ensure that failures remain rare.

The American Wind Energy Association has an active Safety Committee with members from all sectors of the turbine industry, including owners, manufacturers, suppliers, construction contractors, and others. The Safety Committee meets on a regular basis and has a number of ongoing initiatives to support a safe industry. Those include safety conferences, discussions with agencies like OSHA (the Occupational Safety and Health Administration) and other trade associations, technician training and community college programs, all aimed at supporting a consistently safe and reliable wind business.

Regards,
Thomas O. Gray
American Wind Energy Association
www.powerofwind.org
www.awea.org