The EU-funded MARES project aims to develop a novel design of superconducting generator integrated into a wave energy converter (WEC). The superconducting generator consists of two parts, one assembled using REBCO tapes and the other using magnesium diboride (MgB₂) wires, with the latter offering a more cost-effective alternative. Assessing the optimal design of MgB₂ wires for this application is not straightforward, since AC losses represent a major technical issue of this device. In this work, a genetic algorithm is applied to determine the optimal design of the MgB₂ wires. The algorithm is coupled with a finite element method (FEM) electrodynamic model that computes the AC losses in the MgB₂ wires. The goal of the algorithm is to identify the key parameters of the wire configuration (filaments number and diameter, fill-factor, wire diameter, twist pitch) minimizing the AC losses in the device operating conditions.

ABSTRACT Oscillating water column (OWC) breakwaters have become promising in recent years for their wave energy conversion and wave protection functions. However, the changes in structural hydrodynamic performance induced by the multi-chamber design still require further in-depth investigation. In this study, a two-dimensional numerical wave tank based on the Smoothed Particle Hydrodynamics (SPH) method is first established and validated using a box-type floating breakwater case and a fixed OWC simulation. Subsequently, three OWC structures with varying chamber numbers are simulated under seven incident wave periods. The effects of chamber number on hydrodynamic performance, including wave transmission coefficient and three-degree-of-freedom motion responses, are analyzed. Results show that in low periods, the single-chamber structure exhibits the lowest transmission coefficient, the two-chamber the highest, and the three-chamber intermediate. Motion responses generally show a monotonic upward trend with increasing period, but sway and pitch reach peaks under medium wave periods in some cases.

Much of the existing literature for wave energy converters focuses on devices tailored to grid-scale performance. In this paper, we present the development of TigerRAY, a small, blue-economy scale wave energy converter, designed to generate 100 W in fetch limited waves. This development process involved in-lab dynamometer testing, two years of drifting field tests, and a two month moored deployment on Lake Washington. Through this process, we show the impact of proper ballasting to TigerRAY's performance, and highlight the importance of dynamometer testing to PTO development and characterization. We also show that power electronics are critical not only to the power output of the device, but to the device dynamics as well. We demonstrate the feasibility of a wave energy converter hosting a dock for an uncrewed underwater vehicle in the field, successfully docking the vehicle with the wave energy converter in all six demonstration attempts. Finally, we provide analysis of data from field testing. TigerRAY's relationship between power output and significant wave height remains relatively constant through changing wave directions, float locations, and power electronics functionality.

Maximizing the durability and reliability of offshore wind farms is essential for the clean energy transition. In this work, we demonstrate how wave energy converter (WEC) farms can shelter offshore wind farms from cyclic wave loading, resulting in significant reductions in wave-induced turbine fatigue damage. Using experimentally validated hydrodynamic models, we show that modeling WEC energy dissipation through fluid structure interactions rather than rated power provides an unbiased analysis of different architecture's sheltering capabilities. Through the system-level model, we observe that even small reductions in wave height propagate to the levelized cost of energy (LCOE) of the wind farm, resulting in a 4.94% decrease in LCOE with a 6% reduction in wave height. Additionally, WEC farms can benefit from this co-location by sharing siting costs, operation and maintenance teams, and mooring and transmission cables with the offshore wind farm. This work advances the design of integrated wind-wave systems, supporting resilient, cost-effective offshore renewables for global deployment.

To solve the maximum power point tracking control problem of wave energy conversion systems, a prescribed performance fixed-time H ∞ tracking controller is proposed. The mathematical model of direct-drive wave energy conversion system with external disturbances is established. The main novelties are as follows: (1) Prescribed performance control is integrated with fixed-time control, and the initial value of the prescribed performance function is introduced into error conversion to solve the problem that the initial error of the system exceeds the prescribed boundary, and the tracking error of the system converges to zero within a fixed time. (2) Radial basis function neural networks are designed to approximate the uncertainties caused by parameter changes and compensated in the controller within a fixed time. (3) H ∞ performance criterion is introduced to attenuate external disturbances, so the robustness of system is enhanced. The simulation results show that the proposed controller is better than finite time control.

Predicting nonlinear motion instabilities in wave energy converters using data-driven methods

Wave energy converters: a comprehensive review of research progress, key challenges, and future trends

Wave energy is among the most promising renewable resources, but its widespread adoption has been constrained by its high levelized cost of electricity (LCoE). The dual use of wave energy converters (WECs) and wave farms for both coastal protection and renewable energy generation offers a promising pathway to lower costs while addressing coastal erosion. Despite this potential, no regional-scale assessment has yet examined the dual-use of WECs and wave farms in Caribbean Small Island Developing States (SIDS), where energy dependence and coastal erosion remain pressing challenges. This study develops a novel dual-use screening index to evaluate the combined potential of wave farms across four representative Caribbean SIDS: Barbados, Jamaica, St. Lucia, and The Bahamas. Long-term ERA5 wave data were used to estimate mean and maximum deep water wave power, while GEBCO bathymetry defined suitability zones (onshore, nearshore, offshore). Shelf area, wave power statistics, and zone-specific weights reflecting coastal protection benefits were combined into a standardized framework to enable cross-island comparison. Results highlight strong contrasts between islands: Barbados and St. Lucia exhibit wave power concentrated nearshore, suggesting strong dual-use potential, whereas Jamaica and the Bahamas trade lower wave energy resources for larger available shelf areas. The dual-use index highlights the most promising locations where energy generation and erosion mitigation can be jointly maximized. This study provides the first regional screening-level assessment of dual-purpose wave farms for Caribbean SIDS, combining wave resource indicators and coastal protection metrics to identify and rank candidate zones, introducing a transferable framework that links renewable energy potential with coastal protection benefits. The approach provides a foundation for future modelling, policy, and planning toward sustainable energy and coastal resilience, while offering actionable insights for Caribbean SIDS that advance both climate adaptation and progress toward the Sustainable Development Goals (SDGs). • First study to assess dual-use wave energy potential in Caribbean SIDS. • Integrated ERA5 wave data and GEBCO bathymetry for resource mapping. • Developed a novel dual-use screening index for energy and coastal protection. • Revealed new regional opportunities for coastal resilience and renewable energy. • Provides a foundation for future planning and SDG-aligned policies.

Transverse flux PM linear generator (TF-PMLG) enables a higher power density under low-speed wave characteristics. However, thrust pulsation and magnetic leakage are major issues in these generators. To address the foregoing problems, a hybrid excitation TF-PMLG is proposed. However, it presents significant control challenges due to large phase inductance and non-negligible internal resistance, particularly under conditions of insufficient bus voltage. Additionally, the necessity for electromagnetic thrust to adapt in real time to wave variations further intensifies the demands on the dynamic performance of the control system. To this end, this paper proposes a model predictive thrust control (MPTC) strategy based on optimal flux linkage vector selection. It can effectively mitigate thrust fluctuations of the generator in response to wave action. Furthermore, a dynamic flux-enhancing strategy is developed, which can reduce the dependence on bus voltage magnitude, thus increasing the peak thrust of the generator. Finally, simulations and experimental results are provided to validate the effectiveness of the proposed MPTC methods in direct-drive wave energy converter (DDWEC) system.

A hybrid CNN-Transformer model with optimized VMD for fault diagnosis of wave energy converter gearboxes

Leveraging defects in arrays of heaving cylinders for enhancing the performance of point absorber wave energy converters

Hydrodynamic analysis of a very large floating structure coupled with an array of wave energy converters

Numerical study on the hydrodynamic performance of a coupled oscillating buoy-oscillating water column wave energy converter

Multi-objective optimization and performance analysis of a 10 MW offshore wind-wave hybrid system with built-in wave energy converters

Event-triggered neural network prescribed performance control for wave energy conversion system under input saturation

Abstract The Wild Horse Optimizer (WHO) has demonstrated competitive performance in various optimization tasks; however, it often exhibits rapid convergence in early iterations and limited refinement capability in later stages, particularly in multimodal and high-dimensional problems. To address these limitations, this paper proposes an improved WHO framework from a mechanism coordination perspective, in which multiple search strategies are systematically organized according to different stages of the optimization process rather than introduced independently. The key novelty lies in coordinating multiple mechanisms across the search trajectory, thereby enabling a structured balance between global exploration and local exploitation instead of relying on isolated enhancements. Specifically, a random running strategy is used to enable non-local relocation when population diversity decreases, an adaptive weight mechanism regulates search intensity according to the population state, and an enhanced waterhole interaction scheme improves guided information exchange among individuals. In addition, chaotic perturbation and Lévy flight are incorporated to maintain diversity and support long-range transitions throughout the search process. The proposed method is evaluated on benchmark functions, constrained engineering design problems, and a practical wave energy conversion optimization task. Experimental results show that the proposed algorithm achieves faster convergence, improved solution quality, and stronger robustness than the original WHO and several representative metaheuristic algorithms. In the wave energy application, the optimized PTO parameters increase the average power output to 119.21,W under regular waves and 103.04,W under irregular waves, corresponding to improvements of 5.83% and 8.57% over WHO, respectively. These results demonstrate that the coordinated mechanism design effectively enhances both global exploration and local refinement, making the proposed method a reliable optimization tool for numerical benchmarks and practical engineering systems.

ABSTRACT Wave energy converters (WECs) are highly sensitive to geometric design, which directly affects hydrodynamic response and energy capture efficiency. This study investigates the influence of geometric modifications on the hydrodynamic behavior of a two-body floating WEC using a combined experimental-numerical approach. Wave tank experiments were conducted under regular wave conditions using a 1:10 scale model to characterize the baseline response and validate the numerical model developed in ANSYS AQWA. Two geometric modifications were examined numerically: window openings in the outer buoy and elongation of the connecting tube between the buoys. The window configuration reduced relative motion amplitude by approximately 7%, lowering energy capture potential. In contrast, elongation of the connecting tube increased relative motion by up to 20%, improving power take-off performance. The results demonstrate the significant role of geometry-driven coupling effects in the optimization of multi-body floating WEC systems..

This study introduces a novel approach using two deep learning agents, trained with the twin-delayed deep deterministic policy gradient (TD3) algorithm, to replace the PI controllers used for the control of grid-connected Archimedes Wave Swing (AWS) wave energy conversion systems. The generator converter's controller has two mandatory objectives: minimizing losses in the stator and maximizing energy extraction from incident sea waves. These goals are achieved by controlling the generator's dq currents using a TD3 agent on the rectifier side. In addition, the grid-side inverter's controller is responsible for regulating both the DC link and the point-of-common-coupling voltages. In the new configuration, two approaches are proposed in this work: either a single deep learning agent replaces the four proportional-integral (PI) controllers on the inverter side, or a hybrid approach combining two PI controllers with a TD3 agent. To verify the reliability of the TD3 agents, the system is analyzed in both steady and transient states under fault conditions. Furthermore, the TD3 agents' performance is benchmarked against the classical PI controller configuration in MATLAB Simulink. The results demonstrate better dynamic and steady-state responses from the hybrid-TD3 agent on the grid side than from the full PI classical configuration.

Autonomous marine pollution-monitoring platforms must operate for extended periods in remote, harsh sea environments with limited maintenance access, making power-source selection a critical design choice. This study develops a transparent multi-criteria decision-making (MCDM) framework to compare five candidate power options, hybrid systems, wave energy converters, photovoltaic modules, fuel cells, and small wind turbines, against criteria spanning technical performance, economic cost, and environmental impact. Criterion weights are derived objectively using the entropy method, and the alternatives are ranked using two complementary MCDM techniques: VIKOR, which identifies compromise solutions closest to an ideal point, and ELECTRE, an outranking approach based on concordance/discordance pairwise comparisons. Both methods consistently select hybrid power systems as the top option, with wave energy ranked second. Solar and fuel-cell solutions fall in intermediate positions, while small wind turbines rank lowest across evaluations. A sensitivity analysis that perturbs criterion weights by ± 10%, ± 20%, and ± 30% confirms that the ranking order remains stable over a broad range of weighting scenarios. The proposed entropy-VIKOR-ELECTRE framework provides a quantitative and defensible basis for selecting robust power systems for long-endurance autonomous marine pollution-monitoring deployments.

ABSTRACT In this paper, a two-body point absorber wave energy converter (WEC) equipped with a bistable mechanism is investigated. The power take-off (PTO) is simplified as a linear model for the focus on the coupling mechanism between a bistable system and multi-body hydrodynamics. First, the mathematical model of the WEC was developed and verified through the comparison of float response amplitude between the time domain and frequency domain. Subsequently, key bistable parameters were selected to conduct parametric and modal analysis on the heave response, oscillation states, and power capture efficiency of the WEC based on coaxial double cylinders, with respect to the float principal dimensions. The influence mechanism of the bistable mechanism on power capture was also investigated. Increasing the outer radius of the torus, reducing its draft, and enlarging the spar radius were found to enhance the power capture efficiency and to broaden energy capture bandwidth. The inter-well response of the bistable mechanism reduces the natural frequency of the torus and brings it closer to the wave frequency, resulting in the overall bistability of the WEC and improved power capture efficiency. Finally, the power capture performance of the WEC with an actual float configuration (PowerBuoy and WaveBob type WECs) were studied, analyzing the influence patterns of float hydrodynamic coefficients on power capture efficiency. Compared to the PowerBuoy type WEC, the WaveBob type WEC exhibits greater hydrostatic stiffness for its spar, leading to a significant improvement in power capture efficiency under the effect of different bistable stiffness.