Date of Award

Spring 2024

Project Type

Thesis

Program or Major

Civil and Environmental Engineering

Degree Name

Master of Science

First Advisor

Yashar E Azam

Second Advisor

Erin Bell

Third Advisor

Philippe Kalmogo

Abstract

In today's world, meeting the growing energy demand is crucial to sustaining the modern way of life. This has primarily been achieved through non-renewable sources, which are depleting and causing environmental harm. To tackle these challenges, a shift towards renewable energy sources is essential. The offshore wind sector, in particular, is rapidly expanding, exploring suitable sites for offshore wind farms and Floating Offshore Wind Turbines (FOWT). This study looks at the viability of the Gulf of Maine for FOWTs based on extreme environmental conditions associated with a 50-year storm return and wind directionality. The International Energy Agency (IEA) 15-MW Reference Wind Turbine (RWT) supported by the University of Maine (UMaine) VolturnUS-S semisubmersible platform was used to conduct this research. Through probability analysis extreme mean wind speeds and significant wave heights associated with this storm event were determined. Variability in extreme wind speeds across different directions in the Gulf of Maine was observed. Consequently, the response of FOWTs, particularly the tower, was analyzed with wind speed direction varied in 5-degree increments, while wave directionality remained constant due to data constraints of buoy 44005 provided by the NOAA. These climate conditions, along with parameters from IEC 61400-3 DLC 6.1, were integrated into Horizontal Axis Wind Turbine Simulation Code 2nd Generation (HAWC2) to evaluate the wind turbine's dynamic response. Results indicated that the tower maintained stable stress levels within yield strength limits, despite variations in wind direction. The tower base showed elevated normal stresses as the wind direction aligned more closely with that of the waves, while the tower top experienced a decrease in normal stresses. In both cases, the bending moment in the x direction played a significant role. Conversely, shear stresses exhibited an opposite trend, with the bending moment in the z direction having the most impact for the tower top and the force in the y direction for the base.

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