Wave Energy Extraction from buoys

Abstract

Different types of Wave Energy Converters currently tested or under development are using the vertical movement of floating bodies to generate electricity. For commercial applications, arrays have to be considered in order to produce a significant power. In this thesis, we investigate the interaction between floating buoys from an hydrodynamic point of view. The objective is to derive general features of energy extraction without resorting to direct numerical simulation by applying the method of homogenization. After reviewing characteristic aspects of power extraction from a single oscillating body, we study a first configuration where many small buoys are placed close to each other. We show that a collection of point absorbers extract more energy than a single big buoy and that the bandwidth is wider. We also show that multiple scales analysis allows to treat radiation problems, and that if the incoming wave length is a multiple of the spacing between buoys, energy extraction can be reduced in a very significant way due to a very strong reflection, which prevents the wave from traveling inside the array.