Electric Propulsion in Short Sea Shipping

Short sea shipping, the movement of freight along coasts and inland waterways, is more efficient and environmentally friendly for transporting large quantities of product. While marine transport may displace numerous diesel trucks, conventional propulsion systems still rely on petroleum fuels and the old engines found in most freight vessels produce harmful exhausts. An investigation was undertaken to determine the technical, economic, and environmental potential for an electric propulsion system in short sea shipping operations within New York State where numerous waterways provide a marine highway option that can be used for freight transport. Duty cycle information obtained from tugs during real-world operations in the New York City Harbor was used in the analysis. Three drivetrain configurations, a series hybrid-electric tug with energy storage, a series hybrid-electric tug with plug-in capability, and a series hybrid-electric tug with exchangeable energy storage capability were analyzed using the acquired load profiles. Modeling results indicate that the fuel savings is highly dependent on the application. The plug-in configuration is likely to be the most cost effective concept based on the large increase in additional fuel savings for the minimal cost to add this capability. This study shows the value of modeling with real-world duty cycles to estimate system benefits. An ongoing study evaluating the potential benefits of electric propulsion for New York State Canal Corporation maintenance vessels may identify a favorable application for this technology due to the low power requirements and regular recharging opportunities within their operations.