Wind conditions in category 1-3 tropical cyclones can exceed wind
turbine design standards
Abstract
Offshore wind energy deployment in the US is expected to increase in the
years to come, with proposed wind farm sites located in regions with
high-risk for tropical cyclones. Yet, the wind turbine design criteria
outlined by the International Electrotechnical Commission for extreme
events may not account for the severe wind conditions in tropical
cyclones, even the weaker storms that are likely to reach mid-Atlantic
wind resource areas. To evaluate if current design standards capture the
extreme conditions of these storms, we perform idealized large-eddy
simulations of five tropical cyclones (two category-1, two category-2,
and one category-3 storms) using the Weather Research and Forecasting
model. Wind conditions near the eyewall of category-1, category-2 and
category-3 storms can exceed current design standards for offshore wind
turbines. Hub-height winds can exceed design criteria for Class I and
Class T turbines for 50-year recurrence periods. Moreover, wind speed
shear across the turbine rotor layer is larger than assumed in design
specifications. Vertical variations in wind direction across the turbine
rotor layer are also large for tropical cyclones of all intensity
levels, suggesting design standards should include veer, which can
amplify loads in wind turbines.