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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]

Recent studies have focused on optimising wave energy converter (WEC) designs, maximising their power performance and techno‐economic feasibility. Reliability has yet to be fully considered in these formulations, despite its impact on cost and performance. In this study, this gap is addressed by developing a reliability‐based design optimisation framework for WEC hull geometries to explore the trade‐off between power performance and power take‐off (PTO) system damage equivalent loading (DEL). Optimised hull geometries for two sites are considered (from the centre of the North Sea and off the west coast of Norway), and two directions of motions (heave and surge). Results indicate that site characteristics affect the potential power production and DEL for an optimal WEC design. These are also affected by the direction of motion for power extraction, which also significantly changes optimal hull shape characteristics. Optimal surging WEC designs have edges facing oncoming wave directions, while heaving WECs have pointed bottoms, both to streamline movement. Larger, more convex WECs result in greater power production and DEL, while smaller, more concave WECs result in lesser power production and DEL. These findings underline the importance of considering WEC hull geometry in early design processes to optimise cost, power production, and reliability. [ABSTRACT FROM AUTHOR]

This work investigates potential cost reduction trajectories of three emerging offshore renewable energy technologies (floating offshore wind, tidal stream, and wave) with respect to meeting ambitious cost targets set out in the Strategic Energy Technology Implementation Plans (SET-Plans) for Offshore Wind and Ocean Energy. A methodology is presented which calculates target costs for current early-stage devices, starting from the 2030 SET-Plan levelised cost targets. Component-based experience curves have been applied as part of the methodology, characterised through the comparative maturity level of each technology-specific cost centre. The resultant early-stage target costs are then compared with actual costs for current devices to highlight where further cost reduction is still required. It has been found that innovation and development requirements to reach these targets vary greatly between different technologies, based on their current level of technological maturity. Future funding calls and programmes should be designed with these variables in mind to support innovative developments in offshore renewables. The method presented in this paper has been applied to publicly available cost data for emerging renewable technologies and is fully adaptable to calculate the innovation requirements for specific early-stage renewable energy devices. [ABSTRACT FROM AUTHOR]

Current wave energy development initiatives assume that available designs have the potential for success through continuous learning and innovation-based cost reduction. However, this may not be the case, and potential winning technologies may have been overlooked. The scenario creation tool presented in this paper provides a structured method for the earliest stages of design in technology development. The core function of the scenario creation tool is to generate and rank scenarios of potential Wave Energy Converter (WEC) attributes and inform the user on the areas of the parameter space that are most likely to yield commercial success. This techno-economic tool uses a structured innovation approach to identify commercially attractive and technically achievable scenarios, with a scoring system based on their power performance and costs. This is done by leveraging performance and cost data from state-of-the-art wave energy converters and identifying theoretical limits to define thresholds. As a result, a list of scored solutions is obtained depending on resource level, wave energy converter hull shape, size, material, degree of freedom for power extraction, and efficiency. This scenario creation tool can be used to support private and public investors to inform strategy for future funding calls, and technology developers and researchers in identifying new avenues of innovation. [ABSTRACT FROM AUTHOR]

Wave Energy Converters (WECs) with optimised geometries and control systems have been developed in recent years to advance marine energy technologies towards commercialisation. In particular, a number of WEC hull geometry optimisation studies have been performed, due to the high cost reduction potential associated with the device structure. However, no standard and consistent method has been established for this purpose. For example, different optimisation formulations (single-objective and multi-objective), have been used, applying different optimisation algorithms. Additionally, a range of objective functions have been employed, where power maximisation has been represented through a variety of metrics, and cost minimisation expressed with diverse cost proxies. The goal of this study is to address the challenge of finding a suitable optimisation problem formulation with single-objective or multi-objective implementations, and the respective objective functions, that support the exploration of shapes that reduce the levelised cost of energy. Results show that submerged surface area cost proxies are more suitable for this purpose than volume-based cost proxies. Results from a multi-objective optimisation formulation can provide a good understanding of the solution space, whereas results from single-objective studies can be used for seeding these multi-objective optimisation approaches. • Different objective functions are compared for wave energy converter optimisation. • Using volume based cost proxies results in more complex WEC shapes. • From a techno-economic perspective surface area based cost proxies are more suitable. • Multi-objective implementations are studied and compared to single-objective approaches. • Single-objective results should be used as inputs to multi-objective formulations. [ABSTRACT FROM AUTHOR]

It is key in the development of wave energy systems to aim at designing economically competitive solutions that enable maximal annual energy production. Previous studies identify the Wave Energy Converter (WEC) structure, i.e. the hull, to have one of the largest cost reduction potentials. Due to this potential, geometry optimisation of WECs has been previously considered, however, most of these studies have been limited by the simplicity of the employed geometrical shapes and the lack of accurate cost models. It is, therefore, important to include an adaptable geometry definition capable of generating diverse WEC shapes, and to account for other factors that can have an effect on costs. These considerations result in a more challenging optimisation problem, and a more complex objective function. The goal of this study is to address the challenge of finding a suitable and efficient optimisation method for WEC geometry design. In this paper, different geometry definitions, such as using simple shapes or B-spline surfaces, and different meta-heuristic optimisation algorithms, such as genetic algorithms or particle swarm optimisation are applied to this problem to find the most suitable choices. Results show an improvement in final objective function values of up to 224% when using an adaptable geometry definition and up to 11% when employing the most suitable optimisation algorithm compared to previous results. In conclusion, the choice of the different elements of the optimisation formulation have a large impact on the quality of the optimisation results and should be based on preliminary studies as presented here. • A comprehensive optimisation method is required for wave energy converter design. • The main elements for wave energy converter geometry optimisation were studied. • Meta-heuristic algorithms are suitable for WEC geometry optimisation. • Genetic and particle swarm optimisation algorithms suit different study cases. • Geometry definitions based on bicubic B-splines achieve better optimisation results. [ABSTRACT FROM AUTHOR]