Estimation of extreme wave and wind design parameters for offshore wind turbines in the Gulf of Maine using a POT method

• Metocean design conditions for the Gulf of Maine are estimated using buoy data.
• Design conditions are required to support the design of offshore wind turbines.
• Ten to twenty-five years of buoy data at five locations were examined.
• A POT extreme value analysis of the waves and wind speed conditions was completed.
• The predictions compare well with past predictions for open water sites.

Design parameters needed for the development of Maine׳s offshore wind resource are calculated using Gulf of Maine buoy data. Extreme values of the significant wave height and mean associated peak period, eight minute average wind speed, and five second average gust wind speed are estimated using a Peaks Over Threshold (POT) extreme value estimation technique. Wind shear coefficients and gust factors are also estimated. Seven to thirty-two years of buoy data at five locations near areas of possible interest to Maine׳s offshore wind industry were examined. Buoy data was obtained from the University of Maine and the National Oceanic Atmospheric Administration. Predictions of extreme significant wave heights in this study compare well with past shipboard and hindcast predictions for open water sites. Sites closer to shore show larger differences from past predictions due to the large areal scale of the earlier studies. Extreme wind speeds and shear coefficients compare well with coastal onshore wind speeds published by the American Society of Civil Engineers.