Passenger ferries with fully electric drive systems – sizing, technical evaluation, and life cycle assessment for operation in Swedish waters

Report, 2024

The shipping sector is in a transition to be fossil free and there are several different alternative solutions. For short sea and costal shipping battery-electric propulsion is very promising. The aim of this study was therefore to conduct a full life cycle assessment of a combustion propelled passenger ferry operating in Swedish waters, as well as of a retrofitted battery electric version of the ferry. A further aim was to examine the proportions of the environmental burden that falls on the battery, driveline components and the rest of the ship, as well as to compare the results with the diesel driven version. The study was based on the passenger ferry Vesta which operates by Styrsöbolaget between mainland and islands in Gothenburg’s southern archipelago, as well as on the river Göta Älv. The project resulted in the dimensioning of a fully electric drivetrain including battery pack. Electric motors with and without magnets were studied, an inverter unit and batteries of two different chemistries, and optimized for energy respective power. Technical results were then linked to a life cycle assessment model where the data inventory analysis for the electric drivetrain and operation was the focus. The charging infrastructure and the remaining parts of the vessel were also included in the inventory model, however in a more general manner. Then all parts were compiled into an environmental impact assessment regarding global warming, local emissions and resource use. All battery-electric ferry options investigated was shown to lower the global warming potential with more than 90% compared to an equivalent diesel-electric ferry using MGO.