Fatigue Assessment of Wave Energy Converters

 

Prof. Trevor Whittaker

Dr. Matt Folley

Dr. Paul Lamont-Kane

 

 

 

 

 

As marine renewables progress towards and through the pre-commercial prototype deployment stage, it is essential that increased attention is given to the efficient and intelligent design of machines with a view to minimising the Levelised Cost of Energy (LCOE) generated. Wave Energy Converters (WECs) are designed to couple heavily to incident water waves, extracting the maximum amount of energy possible from a sea. Devices will therefore be subjected to many millions of high intensity load cycles over a typical deployment and so the combined consideration of hydrodynamic performance alongside the undertaking of an accurate fatigue assessment is crucial for the assessment of structural efficiency and the identification of critical structural components.

Here at QUB research is ongoing on the coupled performance/loading assessment of WECs with particular focus on coupled fatigue loading estimations. The research aims to determine the potential use of spectral domain methods in the coupled performance/loading assessment of a variety of the most commonly developed WEC concepts including heaving buoys, pitching flaps and multi-bodied rafts/attenuators. Spectral domain modelling is a technique set in the frequency domain which may provide estimates of a dynamic device’s motions and loading with a degree of accuracy comparable to that of the time domain however at a fraction of a percentage of the computational cost. This work will investigate the potential for the widespread application of spectral domain methods to wave energy applications and subsequently undertake a comparative assessment of the structural efficiencies of the most common device types considered. Within the design space of each WEC concept, further works will be completed on the determination of optimum design parameters leading to suggestions for overall improved design practices.