BiOscillator – Approach and Experimental Methodology for a novel Type of Wave Energy Converter

Supervisor: Craig Stevens (National Institute of Water and Atmospheric Research in Wellington, New Zealand)
With renewable energy technology, such as wave8power, being an eventually inevitable alternative to fossil fuels, New Zealand is one of many countries moving forward in the sector. It is well positioned to harness wave energy from its energetic ocean. This thesis presents the thinking behind a novel WEC (Wave Energy Converter) titled BiOscillator, the methodology and approach of a scale8model experiment conducted and an analysis and discussion of the results in terms of the experimental set-up and different configurations. The idea evolves around biological elements being incorporated in an oscillating WEC, functioning as the suspended elements and transferring energy from wave motion on the man-made parts, eventually producing electricity by converting the captured kinetic energy into electrical energy. This provides the advantage of the sensitive parts being less likely to be harmed during storms and adds additional merits by introducing harvestable aquaculture into the WEC. Different species of kelp and mussels were considered. Macrocystis pyrifera and Perna canaliculus were the ones settled on in the end. Various approaches and designs for the WEC itself were assessed and once the inapplicable ones had been ruled out, a methodology and procedure for testing different set-ups was conceived and adjusted. Once the experiment had been set-up three different parameters – tension, acceleration and velocity- were being measured for different configurations in a small tank. The results point towards a possibly optimal point in kelp length and allow us to draw conclusions on the drag forces for the set-ups that had mussel ropes attached to them. Drag and inertia forces will need further assessment in future research. A more thoroughly constructed and bigger set-up is recommended to address challenges to come. Further methodological recommendations are given in the discussion and future research challenges are mentioned in the conclusion.