Alternative Propulsion Systems and Low/Zero Carbon Fuels for Different Marine Vessels

In 2022, shipping was responsible for around 706 million tonnes of carbon dioxide emissions, up 5% from 2020 and back to 2017-2018 levels. To accelerate the energy transition and reduce emissions in this sector, the International Maritime Organization (IMO) has set ambitious goals requiring all stakeholders' radical actions. Several solutions have been proposed such as cruise speed reduction, on-board installation of a Carbon Capture and Storage system, use of low/zero carbon fuels in conventional internal combustion engines, and introduction or replacement of the main and auxiliary engines with novel technologies. Thanks to their high energy conversion efficiency, and reduced environmental impact, the interest in fuel cell-based systems for shipping propulsion has been rising in the last few years. In this work, the replacement of fossil fuel-based marine engines with fuel cell technology is analysed from technical and environmental points of view. A preliminary technical assessment, aiming at defining different powertrain configurations, is performed by starting from the characterization of the selected ships, in terms of installed power, navigation routes, and load profiles. The feasibility of the proposed solutions is evaluated by considering the fuel consumption and the emissions avoided with respect to the conventional solutions.