Consideration of a Rotary Power Take-Off Mechanism as a Wave-Energy Converter on the WindFloat Platform

The possibility of incorporating a wave-energy extractor into a current design of the WindFloat platform is examined. First, to absorb wave energy, a rolling cam shape, with rotary power take-off, is attached to a tubular truss member of the WindFloat located above the calm-waterline. Based on the assumption that the extractor is operating in beam seas, numerical predictions for the coupled 3-DOF system (surge, heave and pitch motions) were completed for an ideal-fluid situation. The degradation of the performance of the wave energy extractor because of viscous effects was discussed in [1]. Second, a design of a versatile bi-directional rotary system, named the UC Berkeley Double-Ratchet Mechanism (UCB-DRM) was made. This mechanism can produce a unidirectional rotational motion, thus facilitating the power take off by a generator. A physical unit was constructed. The efficiency and performance of this mechanical system is assessed by introducing a known, bi-directional torque input and measuring the torque output.