A DESIGN BY OPTIMISATION APPROACH FOR HYBRID PROPULSION SYSTEMS SIZING USING ACTUAL SAILING PROFILES

Hybrid propulsion is considered a promising alternative to diesel mechanical propulsion which can assist the maritime industry to mitigate its contribution to climate change. The energy performance of new designs for most ship types is evaluated with the regulated Energy Efficiency Design Index (EEDI), though its limited consideration of one design point in calm water conditions and installed rated power is characterised as insufficient or even dangerous by many authors. Nevertheless, individual sailing conditions are expected to influence the resulting carbon footprint. The automotive and aviation industries have already adopted the energy assessment of new designs over operating cycles such as the Worldwide harmonized Light-duty vehicles Test Cycle (WLTC) or the Landing and Take-Off cycle (LTO). This paper demonstrates a new approach for the resizing of the hybrid propulsion system of an ocean patrol vessel of the Royal Netherlands Navy. It utilizes the actual sailing profile of a vessel based on logged high frequency operational-data. Carbon intensity is predicted by a state of the art digital twin of the vessel’s energy system developed by the authors in a previous stage. Results suggest that calm water conditions can potentially overestimate carbon intensity improvements and point to different optimal designs thus actual profiles must be used in future analyses.