Feasibility study on spar-type floating offshore wind turbine in ice-covered seas

• The feasibility of deploying spar-type FOWTs in ice-covered seas is evaluated, based on their dynamic response to ice-induced loading. • Two-way coupling between the semi-empirical ice model and the wind turbine global simulation tool is implemented. • Comprehensive validation against the published ice basin test data is performed. • The influences of ice thickness, ice drift speed, and wind-ice velocity misalignment angles on the structural response of the FOWT are studied. This study investigates the feasibility of deploying a spar-type floating offshore wind turbine (FOWT) in ice-covered seas, focusing on its dynamic response under ice loads. A semi-empirical ice model focusing on ice loads acting on vertical structure is coupled with the global simulation tool SIMA to assess FOWT responses. The ice model is validated for ice bending and crushing failure modes, respectively. The Offshore Code Comparison Collaboration (OC3) spar-type 5MW FOWT is selected as the reference system. A parametric study is performed to evaluate the effects of the ice thickness, the ice drift speed, and the wind-ice velocity misalignment angle on the structural response of the FOWT, using environmental conditions based on ISO 19906 for the Baltic Sea. The effect of the ice thickness and wind-ice velocity misalignment on the structural response of the FOWT is significant, while the ice drift speed shows a relatively minor impact. The feasibility is evaluated by setting the translational offset limit to 20 % of the water depth and the inclination angle limit to 10°. Different icebreaking cones and mooring system layouts are used to mitigate the dynamic response of the spar structure under ice impact. Results show that adding an icebreaking cone is an effective way to reduce both the dynamic response of the FOWT and the ice forces acting on it. It is found that OC3 spar FOWT maintains acceptable dynamic behavior under the range of the present investigated ice conditions, supporting its technical viability for operation in ice-covered seas.