Semi-Submersible Hybrid Platforms for Wind–Wave Hydrodynamic Performance: High-Fidelity Numerical Simulations powered by SPH

Hybrid wave–wind energy platforms seem a promising way forward to elevate renewable energy power production by blending in wave energy converters (WEC) and wind turbines. This work proposes an extreme performance estimation through high-fidelity software for a power unitcomprising a 5-MW NREL wind turbine and three WaveStar devices using a numerical framework based on DualSPHysics, which implements the Smoothed Particle Hydrodynamics method to solve the fluid dynamics, powered by state-of-the-art GPU parallelization. First, we validate the response of the power unit by relying on sub-component model validations, specifically, validating an OC4 DeepCwind layout under operational frequencies, and, using their spectral representation, we compare the hybrid platform performance during power production. Using incremental sea-states, we employ the model to evaluate the platform-to-WEC sensitivity for two cases: no power absorption and operational, respectively. This investigation shows that the platform heave and pitch motion increase by about two and three times, respectively, when the devices are operating at their optimal damping. On the other hand, the surge motion only increases by around 50%. It is clear – combined wave and wind energy platforms are more susceptible to wave induced loads when the wave energy process is not interrupted, suggesting how WECs combined to FOWTs do not generally provide a stabilizing effect unless more specific strategies are enforced.