Comparison of interaction effects between multi-wave absorber systems

Abstract

With increasing numbers of floating wind farm projects being proposed for sites that also have an attractive wave resource, wave energy converter (WEC) developers are increasingly thinking about how their prospective wave energy developments can best integrate with these floating offshore wind (FOW) projects and how to best utilise the supply chain collaboration opportunities these developments offer. A challenging aspect of co-locating wave energy with wind is the comparatively low ratings of many WEC technologies being developed (<1MW) compared those of floating offshore wind turbines (15MW and upwards). One potential solution is the deployment of multiple WECs on platforms, which can streamline installation and maintenance while delivering multi-MW capacities of wave energy. This co-location approach is supported by an economic study carried out for Wave Energy Scotland by Offshore Wind Consultants Limited, which identified that WECs deployed on their own platforms may be more attractive to FOW project developers in the short-term, from both a technical risk and economic standpoint, than fully hybrid wind and wave platform systems though these might follow in the future. Platforms developed for FOW applications could potentially be utilised, if proven to be technically feasible, or bespoke platforms could be manufactured using the same production lines.

A key factor in understanding whether such multi-absorber platform systems are conceptually attractive is to understand how wave power capture is influenced by hydrodynamic interactions between the absorbers, and between the absorbers and the platform. To gain insight into this Wave Energy Scotland launched a collaborative study in conjunction with the University of Edinburgh in 2022 to look at how power captured by a notional multi wave absorber system is affected by these interactions in a real resource.

This Multi Wave Absorber Platform study has utilised a combination of numerical modelling and tank testing to gain insight into how interaction effects influence this system compared to alternative systems with equivalent absorbers either installed far enough apart for no interactions to occur in any realistic sea states or positioned with the same spacing but without the platform.  Set-up of the numerical and physical modelling for this study were reported in McLean et al. EWTEC 2023.

This paper discusses some learnings from this study with insight into results obtained and challenges encountered.

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