How do ballast water, pitch angle, and tower material impact the optimization of a concrete semisubmersible floating offshore wind turbine?

Despite significant progress in floating offshore wind turbine (FOWT) technology , there are still several challenges, including the design of a cost-effective system. Considerable research has been dedicated to optimizing the floating platform geometry, layout, dimensions, and weight over the past few years, with some focusing on semisubmersible platforms, where steel is often used for both the platform and tower. However, concrete FOWTs may be more cost-effective and reduce the carbon footprint. Other areas requiring further research include the impact of the tower material, maximum inclination angle, and confining ballast water within dimensionally variable compartments during optimization. The study aims to address these points through a hydrostatic optimization of a novel 15 MW concrete semisubmersible FOWT using a genetic algorithm method. The results show that the platform mass reduction for pitch angles larger than 6 degrees is lower compared to that for angles smaller than 6 degrees regardless of the tower material. Moreover, confining the ballast water inside dimensionally variable compartments leads to a lower semisubmersible platform weight. Finally, an initial comparison of raw material costs shows that a concrete platform with a steel tower offers the most cost-effective solution compared to a FOWT entirely made from steel or concrete.