Studying Wave Buoys for Sensing and Renewable Energy

Studying floating wave buoys for sensing and renewable energy

Supervisors

• Jana Orszaghova
  Research Fellow, Centre for Offshore Foundation Systems
• Hugh Wolgamot
  Research Fellow, Centre for Offshore Foundation Systems
• Dirk Rijnsdorp
  Research Associate, Centre for Offshore Foundation Systems

Students

• Riley Aitkin

Project Description

This work consists of two projects. 

• Project 1: Suitability and performance of a small-scale wave buoy for measuring wave conditions  

The first project will analyse the suitability and performance of a very small scale buoy designed for measuring wave conditions. Low cost sensors are opening new opportunities for detailed studies of the ocean environment. Thorough testing of such devices are paramount before their deployment. Within this project the performance of the mini wave buoy will be examined in the state-of-the-art UWA wave flume and the Swan River. 

The student will examine an in-house mini wave buoy instrumented with a 6 degree-of-freedom sensor for tracking its position and rotation in 3D. From these motion signals wave characteristics can be inferred. Detailed testing in the UWA wave flume and in the Swan River, with comparisons against other measurement techniques, will determine the suitability of our low cost wave buoy. Design alterations might be necessary to extend the performance of the mini buoy into the higher frequency range, and this will be examined within the project. 

• Project 2: Dynamics of a resonant floating oscillator and its mooring  

 The second project will study dynamics of a larger floating buoy designed to mimic a wave energy absorption device (ultimately to harness wave energy for electricity production). The buoy, together with its mooring system, has been optimised for the Swan River wave climate, such that it undergoes large heave (up-and-down) motion, which would ultimately result in part of the incident wave energy being absorbed. The surging and pitching motion also play a role, and will be investigated within this project, both numerically and experimentally. This project falls into a range of initiatives at UWA in the renewable wave energy area, which aim to accelerate the development of the offshore renewable energy sector, including wave energy and floating offshore wind.  

The student will analyse behaviour of a resonant oscillator system comprised of a floating buoy and a taut-mooring with a suitable restoring force, which has been optimised to match typical wave conditions in the Swan River. A theoretical model describing the heave, surge and pitch motions of the buoy will be developed. The student will carry out deployment and field monitoring of the system in the river. By varying the draft and the mass distribution within the buoy, the natural frequencies of the buoy can be varied, which will be investigated in the project, in order to maximise heave motion.  The gathered motion and mooring load data will be analysed and compared to theoretical predictions. 

Both projects will build upon previously successfully completed Riverlab projects.  The Swan River will be utilised as a model wave basin, where field tests will be performed. Additional tests, in a more controlled environment, will be carried out in the UWA wave flume. All testing will be underpinned by theoretical and numerical analysis.  

Impacts

Low cost wave sensors will enable the next generation of offshore facilities by providing the data necessary for digital twins. Wave energy is a huge resource in Australia and can power offshore platforms.