Towards the design of a hydrogen-powered ferry for cleaner passenger transport

The maritime transportation sector is a large and growing contributor of greenhouse gas and other emissions. Therefore, stringent measures have been taken by the International Maritime Organization to mitigate the environmental impact of the international shipping. These lead to the adoption of new technical solutions, involving clean fuels, such as hydrogen, and high efficiency propulsion technologies, that is, fuel cells. In this framework, this paper proposes a methodological approach aimed at supporting the retrofit design process of a car-passenger ferry, operating in the Greece's western maritime zone, whose conventional powertrain is replaced with a fuel cell hybrid system. To this aim, first the energy/power requirements and the expected hydrogen consumption of the vessel are determined basing on a typical operational profile, retrieved from data provided by the shipping company. Three hybrid powertrain configurations are then proposed, where fuel cell and batteries are balanced out according to different design criteria. Hence, a new vessel layout is defined for each of the considered options, by taking into account on-board weight and space constraints to allocate the components of the new hydrogen-based propulsion systems. Finally, the developed vessel configurations are simulated in a virtual towing tank environment, in order to assess their hydrodynamic response and compare them with the original one, thus providing crucial insights for the design process of new hydrogen-fueled vessel solutions. Findings from this study reveal that the hydrogen-based configurations of the vessel are all characterized by a slight reduction of the payload, mainly due to the space required to allocate the hydrogen storage system; instead, the hydrodynamic behavior of the H2 powered vessels is found to be similar to the one of the original Diesel configuration; also, from a hydrodynamic point of view, the results show that mid load operating conditions get relevance for the design process of the hybrid vessels.