Parametric investigation of arm-length effects on novel hybrid wave energy converters: performance enhancement through integration of Wavestar units with two-raft-type system

Wave energy is an abundant and predictable renewable source with strong potential to complement existing clean-energy portfolios. In this study, a novel hybrid Linear Point–Wave Energy Converter (LP-WEC) was developed and numerically investigated. The LP-WEC concept integrates multiple Wavestar units with a two-raft-type floater, interconnected via hydraulic (spring-damper) mechanisms, to enhance hydrodynamic coupling and energy absorption. Nonlinear time-domain simulations were performed for three Wavestar arm-length scenarios (short, medium, long) using a single-side symmetric model; final system outputs for the LP-WEC were obtained by mirroring (doubling) the single-side results to represent the full symmetric array, and all cases were evaluated under four representative wave conditions. Analytical formulations were introduced to distinguish incident wave power, absorbed power, and equivalent energy indicators, forming the basis for assessing device-level and system-level performance. Results reveal that the LP-WEC consistently outperforms stand-alone devices when properly configured. In particular, the medium-arm scenario with moderate coupling exhibited the strongest synergy, with the hybrid system achieving 106.8 kWh/day of equivalent daily energy and 39 MWh/yr of annual equivalent energy—representing a two- to threefold enhancement relative to the independent Wavestar and two-raft-type configurations. Conversely, less optimal configurations yielded diminished benefits, emphasizing the sensitivity of hybridization to geometric and hydrodynamic parameters.