Preliminary design of a 75 m Mega Yacht with diesel - Electric hybrid propulsion powered with hydrogen FCs

The naval research and industry are facing with the significant challenge of ensuring carbon neutrality for the future of sustainable transportation. This imperative arises from the fundamental role that this sector occupies in global trade and the transportation of people. To achieve this goal, the use of green propulsions and alternative fuels play a central role, guaranteeing a significant reduction of ships global emissions and the respect of rules imposed in the Emission Control Areas (ECAs), therefore the preservation of the sea. If environmental awareness has been a reality for which efforts have been underway for years in land-based transportation, the same cannot be said for the maritime industry. For this reason, and with the aim of introducing innovative and more eco-compatible solutions, the paper presents the methodology used for the preliminary design of a 75-m Mega Yacht and sizing of the hybrid diesel-electric propulsion system equipped with hydrogen powered fuel cells and pressurized storage. As current technology does not support long-range sailing with full hydrogen propulsion, the hybrid propulsion was preferred. The configuration presented offers the flexibility of full electric sailing for short distances (up to 130 nautical miles) or to access protected areas, while also allowing traditional propulsion when hydrogen refuelling infrastructure is unavailable at ports or when faster sailing is required. The power unit consists of four FCs with a total power of 540 kW, two 180 kW electric motors combined with two 1765 kW thermal engines. The hydrogen storage area is composed of 105 cylinders with a total capacity of 21.3 m3 and a pressure of 350 bar, respecting the current regulations and guidelines for the use of hydrogen and pressurized explosive gases onboard. Furthermore, the IMO criteria were met to verify the feasibility of the idea.