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Wave energy conversion can have a significant role in the transition to a net-zero energy system. However, cost reductions are still required for this technology to be commercially competitive. To achieve commercialisation at a reasonable expense, disruptive innovations at early stages of development need to be enabled. Thus, to explore more of the design space, design limits need to be defined. Although physical limits, such as the maximum capture width and the Budal upper bound, have been defined, more realistic limits considering the variability of the resource, device dimensions and the actual hydrodynamic behaviour of different shapes can help provide further insights. This is relevant to both technology developers and funding bodies wanting to identify potential areas for innovation. In this study, the use of multi-objective optimisation is proposed to explore these limits, by investigating the optimal relationship between average annual power production and device size. This relationship depends on resource level, mode of motion used for power extraction and hull shape. The obtained fundamental relationships fall within the existing physical limits, but provide further insights into the impact of different factors on these limits. This allows for a more direct comparison with the performance of state-of-the-art wave energy converters. • A flexible method to explore wave energy converter design limits is presented. • Design limits for power and volume are obtained with multi-objective optimisation. • The design limits are verified against the state of the art and physical limits. • The method can be used to obtain other types of fundamental relationships. • These relationships help identify areas with potential for disruptive innovation. [ABSTRACT FROM AUTHOR]

Wave energy converter hull shapes have been optimised in the past to find the most suitable design to maximise mean annual power production and minimise costs. However, costs are generally considered through proxies based on the device's size. When using an optimisation process capable of generating very diverse shapes, more complex objective functions may be required to ensure that resulting shapes truly minimise the levelised cost of energy. For this purpose, relevant cost factors with an effect on geometry, such as manufacturability and materials considerations, should be included in the optimisation process. To address this challenge, different strategies for incorporating manufacturability considerations in a wave energy converter optimisation process with an adaptable geometry definition are discussed here. The resulting optimal shapes are compared to the shapes obtained when these additional constraints are not included. The results show that it is possible to generate wave energy converter shapes designed for a particular manufacturing process, as well as in general with improved manufacturability characteristics - based on the shapes maximum curvature. The proposed approaches can be used in future wave energy converter design studies to generate novel and improved shapes while considering their manufacturability. [ABSTRACT FROM AUTHOR]