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Description
The Moored Multi-Modal Multibody (M4) wave energy converter (WEC) has been developed since 2015. To date, float geometry and arrangements have been assumed based on theoretical assumptions of peak power extraction and mean wavelengths at typical wave energy sites. However, this may lead to suboptimal power capture, particularly for sites with multiple modes of occurrence in energy period and wave height.
To evaluate the sensitivity in changing float radius, draft and separation distance of the stern float, this work considers optimisation using a validated linear time-domain hydrodynamic model in OrcaFlex. This is coupled to a Kriging surrogate model, allowing efficient exploration of multiple parameters to identify arrangements with highest performance. Annual energy yield is evaluated by combining with a weighted k-means clustering of the metocean scatter diagram at a site in Portugal.
Each parameter is optimised in 1D isolation, as well as in a 2D combination. 1D results suggest that a 30% reduction in the baseline radius can improve energy yield by up to 35%. Separation distance is also influential, with a convex distribution that peaks at 18% greater energy yield. 2D results show that whilst the contours of energy yield are multimodal, they remain flat in the region of optimal radius and separation distance. Optimal separation is found at 8.6 m, which is larger than the theoretical 6.4 m assumed based on the half wavelength of the peak energy period of the site.
The Kriging framework provides a foundation for future studies, investigating a broader range of float arrangements.
| Topic Area | Advanced Computational Methods and Applications in Marine, Subsea and Offshore Technology |
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