Energy system co-design approach for WECs optimisation: the pendulum wave energy converter case study

The integration of wave energy into power systems is often hindered by a mismatch between device-level performance and system-level needs. Conventional early-stage Wave Energy Converters (WECs) design frameworks, typically guided by levelised cost of energy minimisation, overlook systemic benefits such as aligning renewable production with the system’s demand. This paper proposes a co-design framework that simultaneously optimises WEC design and the renewable energy mix, ensuring that the selected design performs optimally within the overall system while embedding the system’s constraints and performance targets into early-stage WEC design. The approach is demonstrated for the Pendulum WEC (PeWEC) within La Gomera’s isolated grid, in the Canary archipelago, a relevant testbed for microgrid decarbonisation. A multi-objective genetic algorithm couples the PeWEC numerical model with the EnergyPLAN simulation tool to perform hourly-based annual simulations of the whole energy system. The framework identifies Pareto-optimal solutions that reduce CO2 emissions and curtailment, reaching up to 50 % CO2 reduction and 90 % renewable energy sources (RES) share. Results show that optimal devices are not those with maximum stand-alone productivity but those providing power profiles that stabilise the grid and improve RES integration. The methodology enables a comprehensive assessment of wave energy value by embedding system-level constraints directly into the design process and provides practical evidence of how wave energy can support the decarbonisation of isolated grids. The approach is generalisable to other remote, hybrid, or high-RES systems and RES technologies.