One Tall Order

Wind turbines are getting larger and larger. Some turbines' nacelles can be about 160 meters—about 525 feet—above the ground, and the blades can be about 75 meters long.

Undoubtedly an engineering feat, Hywind Scotland also may present unique safety challenges, now that the 30MW wind farm floating off the coast of Scotland has become operational in October 2017. It consists of five turbines, each measuring 830 feet from its base to the tips of its 75-meter blades. The farm could be used in waters half a mile deep, and these five are 15 miles offshore.

It is the world's first commercial floating wind farm, operated by partners Statoil and Masdar; because it can operate in such deep water, it can work in areas that have been inaccessible for offshore wind, Irene Rummelhoff, executive vice president of the New Energy Solutions at Statoil, said Oct. 18.

Larger turbines produce more energy, so manufacturers have continued to develop taller towers and longer blades. But performing maintenance on them is more dangerous as a result.

Two years ago, during ASSE's Safety 2015 conference in Dallas, an insurance industry presenter on wind turbine safety hazards explained that the hazards turbine maintenance workers face—falls, confined spaces, fire hazards, lockout/tagout incidents, first aid injuries, electrical hazards, machine guarding, arc flash—are increased when they're working 300 feet above the ground, which makes rescue or descent more difficult. At sea and miles offshore, it could be particularly difficult.

He showed the audience a photo from a nacelle fire and explained that tool drops were one of the biggest challenges for the maintenance crews.

When that presentation was delivered, turbine height had soared by about 50 percent in just six years, to about 100-110 meters high, and by 96 percent in rotor diameter, and the speaker predicted annual installations would remain high through 2050. Now, some of the largest turbines' nacelles can be about 160 meters—about 525 feet—above the ground, and the blades can be about 75 meters long. The nacelles of the Hywind turbines are "large enough to fit two typical London double decker buses," according to Statoil.

This article originally appeared in the December 2017 issue of Occupational Health & Safety.

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    July/August 2019

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