Performance Evaluation of Wave Energy Converters

Abstract

Ocean waves provide a sustainable, power-dense, predictable and widely available source of energy that could provide about 10 % of worlds energy needs. While research into wave energy has been undertaken for decades, a significant increase in related activities has been seen in the recent years, with more than 150 concepts currently being developed worldwide. Wave energy conversion concepts can be of many kinds, as the energy in the waves can be absorbed in many different ways. However, each concept is expected to require a thorough development process, involving different phases and prototypes. Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. This implicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development stages, and results thereby in a need for specific test objectives and procedures for each development stage. This PhD thesis has looked into the different development stages and more specifically in the performance assessment of wave energy converters based on tank testing and sea trials. The objective was to enhance or complement existing standards and guidelines by making them more transparent, equitable and robust, in order to make power production estimation of fullscale commercial devices more accurate, more comparable between the different development stages and more coherent in between different concepts. Nº MCITN-215414) and administrated by the Wave Energy Centre. Most of all, I wish to thank my supervisor, Jens Peter Kofoed, for giving me the opportunity to perform this work and to have guided and helped me through the whole PhD process. His supervision and advices have made this a very great and learnful experience. Furthermore, I would like to express my gratitude to all the other colleagues at the Department of Civil Engineering that have helped me and made this such a pleasant journey, and in particular the administrative and laboratory staff such as Niels Drustrup, Peter Frigaard, Pernille Bisgaard Pedersen, Jonna Jensen and Anja Bloch. I would also like to acknowledge all the people with who I have collaborated during this research project. They have given me the chance to gain all the experience and knowledge, by trusting me (us) with these interesting projects. This research thesis would not have been the same without the collaboration with the team of the Wave Energy Centre, and especially Izan Le Crom and Frank Neumann, and the collaboration with Tommy Larsen from WEPTOS and the people behind Wave Dragon, WavePiston and Langlee. Finally, I would like to give my special thanks to my parents, my brothers, my girlfriend and all my great friends. Their motivation and continuous support have made this happen and more than enjoyable. I am really very grateful for all you have done for me.

Offshore Wind and Wave Energy Assessment around Malè and Magoodhoo Island (Maldives)

“…The selection of the best leading technologies or the tuning study of a specific WEC is out of the scope of this paper. Regarding the wave-to-wire efficiency of these technologies, from previous extensive literature [81][82][83][84][85][86][87][88][89][90][91][92][93][94][95] it is possible to assume, for a generic WEC, an overall averaged efficiency of 16.5%. In order to cover the Malé electricity demand of 300 GWh/year, a theoretical wave harvester over 20 km long should be required (8.8 kW/m are considered).…”

A database of capture width ratio of wave energy converters

“…Thus, for the purpose of comparison, it was necessary to select a common performance measure, namely annual average of CWR. Note that CWR may also be referred to in the literature as "'non-dimensional performance"' [12].…”

Introduction

“…The peak wave period with the highest annual wave energy contribution (corresponding to the wave energy x probability of occurrence) should be taken into account for this. Table 1.2 gives a rough indication of these dimensions for a full-scale WEC in an average suitable offshore location [13][14][15][16][17].…”