Energy

Offshore Wind Turbines Can’t Take Cat 5 Hurricane Gusts

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Offshore wind turbines built according to current standards may not be able to withstand the powerful gusts of a Category 5 hurricane, creating potential risk for any such turbines built in hurricane-prone areas, new University of Colorado Boulder-led research shows.

The study, which was conducted in collaboration with the National Center for Atmospheric Research in Boulder, Colorado and the U.S. Department of Energy’s National Renewable Energy Laboratory in Golden, Colorado, highlights the limitations of current turbine design and could provide guidance for manufacturers and engineers looking to build more hurricane-resilient turbines in the future.

Offshore wind-energy development in the U.S. has ramped up in recent years, with projects either under consideration or already underway in most Atlantic coastal states from Maine to the Carolinas, as well as the West Coast and Great Lakes. The country’s first utility-scale offshore wind farm, consisting of five turbines, began commercial operation in December 2016 off the coast of Rhode Island.

Turbine design standards are governed by the International Electrotechnical Commission (IEC). For offshore turbines, no specific guidelines for hurricane-force winds exist. Offshore turbines can be built larger than land-based turbines, however, owing to a manufacturer’s ability to transport larger molded components such as blades via freighter rather than over land by rail or truck.

For the study, CU Boulder researchers set out to test the limits of the existing design standard. Due to a lack of observational data across the height of a wind turbine, they instead used large-eddy simulations to create a powerful hurricane with a computer.

“We wanted to understand the worst-case scenario for offshore wind turbines, and for hurricanes, that’s a Category 5,” said Rochelle Worsnop, a graduate researcher in CU Boulder’s Department of Atmospheric and Oceanic Sciences (ATOC) and lead author of the study.

These uniquely high-resolution simulations showed that under Category 5 conditions, mean wind speeds near the storm’s eyewall reached 90 meters-per-second, well in excess of the 50 meters-per-second threshold set by current standards.

Read more at Phys.Org.

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