Backup power supply for a hydrogen-producing offshore wind turbine - a technology comparison

Hydrogen is an important energy carrier for the transition of the energy sector towards decarbonization. An attractive option for its sustainable production are independent offshore wind farms that include all systems for hydrogen production directly on the wind turbine platform. However, these systems face a challenge in maintaining a constant electric power supply on the turbine platform during periods of calm winds as they are not connected to the onshore electrical grid. This study evaluates and compares different technologies for a backup power supply on the wind turbine platform. Due to the limited energy storage capacities of battery systems and, thus, short energy bridging times, systems are investigated that make use of the platform-produced hydrogen (H2) to generate electricity and consequently provide long bridging times. Three different backup power supply systems are investigated: a fuel cell (FC) system combined with a battery storage (BS) system (H2 - FC + BS) as well as a hydrogen internal combustion engine (ICE) with and without a battery storage system (H2 - ICE + BS and H2 - ICE). These systems are examined in terms of efficiency (hydrogen consumption), lifetime, robustness, maintenance requirements, space consumption, and costs. The results suggest that the hybrid system of a hydrogen combustion engine with an accompanying battery storage unit provides an optimal solution, offering a balanced compromise between efficiency, robustness, and minimized maintenance demands.