This report has been prepared by Arup and Cruz Atcheson on behalf of Wave Energy Scotland (WES) as part of a landscaping study of structural forces and stresses for wave energy converters (WECs). It is aimed at developers of WEC devices, and others in the supply chain who have a stake in the design, fabrication, operation and certification of wave energy converters.
The objective of this report is to provide guidance on the application of relevant methods and standards to the design and analysis of WEC devices. The report is not intended to be a definitive nor an exhaustive list of design requirements, rather an interpretation of existing methods and standards in the context of WECs.
The report is broadly presented in two Sections with distinct objectives. Section 1 aims to highlight existing standards and practices that are relevant to WECs; Section 2 aims to propose suitable methodologies for the load assessment and structural analysis of WECs through interpretation of these standards and practices. In this respect, this report builds on previous studies which have provided more practical guidance but may have focused on a single software or device, rather than providing an independent overview of alternative techniques.
The report also includes the results of a survey of active WEC developers. The findings of this survey show that the developer community is making use of a range of tools and techniques. However, these are not always deployed at the right stages of design development, and not necessarily to the level of detail appropriate for the maturity of the technology being pursued. These survey findings suggest that the industry is not operating as effectively as it could and that the industry would benefit if robust methodologies were in place.
A representative example is also presented to demonstrate certain methodologies described in this report. This example highlights some of the challenges that the industry faces which could be addressed through the provision of further guidance beyond this report. Derivation of loads can be an extremely onerous, computationally-intensive exercise beyond the means of some developers. Fabrication details can be complex and non-standard, requiring detailed stress analysis. In particular, methods of improving the efficiency of time history techniques, or improving access to relevant software would be of great benefit.
Finally, the wider community must be acknowledged too. It is not just the design engineers who pursue these issues – there are financiers, insurers, certification bodies and others in the supply chain who need to understand and agree on the process. More established offshore industries are highly regulated and standards and techniques have been calibrated to an internationally accepted safety level, well recognised by investors. A wider understanding, even at a high level, of a more standardised WEC design process would surely improve the industry’s route to commercialisation.