Dynamic behaviour and power performance of a Septon semisubmersible floating wind turbine integrated with wave energy converters

The development of renewable energy sources is inevitable to create a sustainable society for the future. Hybrid wind and wave energy systems are highly regarded as a solution to reduce the cost of energy from offshore wind and waves. The manuscript presents a novel semi-submersible floating wind platform referred to as Septon which is designed with the intention of hosting a multitude of wave energy devices in addition to a wind turbine. Three different wave energy converters (WEC) namely oscillating water column, Torus and point absorber along with their combinations with the Septon platform are considered in the study to understand the dynamic behaviour and power absorption of standalone and integrated configuration. Seven different configurations of the hybrid system are considered for the analysis. Coupled dynamic analysis is performed using an aero-hydro-servo-elastic tool based on boundary element method to analyze the responses of the hybrid platforms under realistic sea states. The motion responses, tower base moments, mooring tensions and power absorption of the hybrid systems are analyzed and compared with the Septon floating wind platform to quantify the effect of various combination of WECs around the wind turbine platform. The numerical results shows that different combinations have a significant impact on the dynamic responses of the platform. The study identifies the hybrid system combining OWC and Torus with the proposed Septon platform as the concept with maximum efficiency in power absorption.