The WaveGyro

Abstract

The WaveGyro – A new Concept for Ocean Wave Energy Capture (Master Thesis by Gebhard Waizmann, University of Southampton 22.09.2011) Abstract Climate change, environmental pollution and the proceeding resource depletion give awareness of the necessity towards more sustainable energy economics. Energy from ocean waves may once play a contributing role towards this step but is as yet in its fledgling stages. This is mainly due to the harsh sea environment, which implies the need for simple and robust wave energy converter. The work presented in this thesis picks up this thought when dealing with the so-called WaveGyro. Introductory chapters explain how this novel concept arose, followed by a detailed explanation of the working principle. The WavGyro utilizes gyroscopes to provide an internal reaction moment against the wave excitation. This internal reaction permits designing a completely enclosed and thus environmentally resistant device. The gyroscopic precession is used to convert the wave-induced moment into a moment that accelerates the flywheels. Equations of motion, which describe the gyroscope kinetics, are deduced. The gyroscopic motions and moment is then implemented into the first-order wave hydrodynamics. Two main approaches to describe the wave excitation are presented. The first approach is superposition of radiation and exci-tation and the second approach makes use of the relative motion principle, which relates the excitation to the extent of displacement. Both approaches are employed to deduce the maximum power capture condition in relation to the device’s dimensions and operational parameters. The influence of real sea state, analytically expressed by the Pierson-Moskowitz spec-trum, on the optimum power analysis is considered and implementation methods are de-veloped. Subsequently the spin-up mechanism is explained and examined; this is the mechanism converting the precession moment into torque accelerating the flywheel. It is shown that a simple configuration, composed of an ordinary cogwheel and a sprag-clutch only is not sufficient for this mechanism. Ideas for alternative mechanisms are considered but require further investigation to allow conclusive results. Finally, an approximate plan for the design of model is developed, which includes basic considerations of scaling laws. Recommendations for further theoretical and practical work on the WaveGyro are provided