Exploring feasible design regions for semi-submersible floating offshore wind turbines under preliminary requirements

In the context of the renewable energy transition, Floating Offshore Wind Turbines are an effective technology for harnessing wind resources farther from the coast, where water depths preclude the use of fixed-bottom solutions. This paper proposes an approach to the preliminary design of semi-submersible floaters, integrating preliminary requirements derived from regulatory and industry guidelines and engineering best practices of the offshore wind community. Four representative semi-submersible configurations are examined, featuring different turbine locations, and in the interconnection among the platform columns, i.e., either a bracing structure or submerged pontoons. For each configuration, the corresponding design spaces are numerically explored to assess and visualize feasible design regions under multiple preliminary design constraints with respect to dimensional, hydrostatic, and dynamic requirements. The results of this study suggest that, among the selected constraints, the heeling angle and the heave period are the most influential factors, while the floating intact stability requirement restricts the feasible region only for the centered configuration with pontoons. Off-centered configurations generally exhibit less flexibility as ballast limitations strongly constrain their feasible region. The proposed methodology aims to support the advanced design stages of the spiral design process, where requirement verifications may necessitate updates to the overall geometry.