Potential for Hybrid and Battery Electric Propulsion Systems for a selected fleet of Inland Waterway Vessels in Germany

Kurzfassung

The integration of inland and coastal shipping represents a crucial step towards the enhancement of supply chain sustainability. In comparison to other modes of freight transport, they offer the lowest emissions per transported unit of volume. Nevertheless, the majority of these vessels are currently still operated with diesel-powered propulsion systems. In order to further reduce the environmental footprint, a shift to alternative means of propulsion is necessary. The lower volumetric energy densities of alternative fuels, coupled with their scarcity, necessitate meticulous planning and adjustments to replenishment schedules. This places additional strain on operations when competing with more flexible transport options, such as road-based freight transport. Therefore, this paper investigates the potential for hybrid propulsion systems in vessels without changes to their operational profile, with the objective of reducing the economic burden on the sector while contributing to more sustainable transport. AIS data is used in order to derive operational profiles of the considered fleet and to calculate their energy demand. From this, an estimation of the potential for alternative propulsion systems can be derived. Moreover, a linear optimisation model is employed to determine the necessary charger powers for a diesel-electric fleet. The median achievable share of electric propulsion in relation to the total energy demand for a selected fleet of 2539 inland vessels running on diesel-electric propulsion systems falls between 12 and 32% depending on the assumptions made regarding energy storage and replenishment times. This equates to a potential for up to 0.7 million tonnes of CO2 tailpipe emission savings. The necessary maximum charger power ranges between 100 and 200 kW, which is in line with the power requirements of state-of-the-art charging systems for road vehicles. In conclusion, it can be demonstrated that hybrid alternative propulsion systems pose a great opportunity to enhance the sustainability of inland and coastal shipping, without necessitating alterations to the vessels' operational profiles. A network of replenishment stations (e.g. electric chargers) is however necessary in order to facilitate this. The requisite charging powers fall within the same range as those typically required for road vehicles.