Mooring Anchor Radius and Spread-Angle Optimization for a 2 MW Semi-Submersible Floating Wind Turbine in Taiwan Strait

Abstract Floating Offshore Wind Turbines (FOWTs), especially the semi-submersible type, have gained significant attention due to their potential to produce energy in deeper water. Nevertheless, the design of such floaters in the typhoon-prone and shallow water environmental conditions of the Taiwan Strait poses some challenges, particularly concerning their mooring systems, which are pivotal to the FOWT’s reliability and cost-effectiveness. The study focuses on the method to find the best combination of anchor radii and spreading angles, which directly impact the behavior of mooring lines, using a 2MW semi-submersible FOWT, TaidaFloat Demo. Critical factors such as mooring line tension and platform motion are investigated to ensure the robustness of the design. The study is conducted by applying optimization techniques to minimize mooring line costs while meeting Class Rules required for the specific environmental conditions of the Taiwan Strait. The result shows that the combination of a spreading angle of 10 degrees and an anchor radius of 17.5 times of water depth is the most cost-effective considering material usage in Taiwan Strait condition. This research contributes insights into the method of design and optimization of semi-submersible floating offshore wind turbines under challenging environmental conditions.