This paper presents a study regarding a novel hybrid concept for both wind and wave energy offshore. The concept resembles a semi-submersible wind platform with a larger number of columns. Wave Energy Devices such as point absorbers are to be displayed around the unit, capturing wave energy while heaving and also enhancing the stability of the platform. In this paper, a first numerical study of the platform’s hull, without Wave Energy Converters, is carried out. Experiments in wave basin regarding the same unit have been conducted and the results are presented and compared to the numerical ones. Both stability and seakeeping performances are assessed and compared.

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This paper presents the numerical and experimental study of a new spring mechanism adapted to a cone-shaped point absorber wave energy converter (WEC). The WEC is intended to be hinged to a floating wind platform with a long arm to create a combined wind and wave harvesting concept. The main objective of the spring mechanism is to improve the platform restoring moments against the wind thrust forces, generated by the wind turbine while contributing to wave energy harvesting. However, the study is presented for the case where the WEC dynamics is investigated outside the platform and attached to a fixed frame, to validate the mathematical model of the WEC concept. Moreover, the impact on the power harvesting performance is investigated with and without negative springs in this scenario.

This paper presents the adaptation of a torus wave energy converter prime mover to an onshore or nearshore fixed platform, by a hinged arm. An optimization code is developed to obtain the best torus and arm geometry, as well as the power take-off parameters, taking as objective function the maximization of total wave absorbed power. In this paper, the power take-off system is modelled as a simplified damper and spring system, where the parameters are optimized for the phase control of the wave energy converter in each sea state, whereas the optimization process is performed with a genetic algorithm. Finally, the optimal result for the productive sea state indicates that the absorbed power is relatively considerable while a better survivability performance is expected from a torus wave energy converter compared to a conventional truncated prime mover.