Influence of resource definition on defining a WEC optimal size

Abstract

International audienceThis work is a follow up from two previous studies which have been investigating the difference in wave resource between sites and the impact this has on the optimal Wave Energy Converter (WEC) size using scatter diagrams of the sites only. This study expands these works by using omni-directional spectra time series to describe the wave resource instead of scatter diagrams. Two well known wave energy test sites are considered: EMEC (Billia Crew) in the North of Scotland and the SEM-REV on the West coast of France. The sloped IPS buoy is used as a case study, and a succinct description is provided. As in previous work, only the hydrodynamic power capture is considered, and no power-takeoff efficiency or cap are introduced. For both sites, around one full year of data is available. Using both the scatter diagrams and the spectra directly, WEC performance metrics are computed for each site and compared. The results show that using spectral time series instead of the scatter diagrams yield lower annual energy productions, and that the highest average capture width ratio is obtained for larger scale devices. Spectral time series allows also the establishment of a simple O&M model. The effect on device availability of annual planned downtime days, of annual failure rates of 1, 3 and 5 and of operability threshold of 2m and 2.5m are investigated. The results show that larger scales might indeed have higher availability, but are exposed to higher risks