How can long-distance battery-powered container ships stack up? A speculative Asia-Europe illustration

Are batteries too costly and insufficiently energy-dense for long-distance shipping? We consider a container ship on a round trip between Asia and Europe under two speculative assumptions. First, in addition to a battery-on-container-ship (“on-ship”) approach, we study an “off-ship” concept where a dedicated battery vessel can power the ship en route. Second, we allow (dis)connection of battery vessels and charging at sea (stops). We describe an economic model that optimises ship speed, number of sea stops, battery capacities and battery vessel adoption for a hybrid (fuel/battery) container ship. Our main insights: (i) the off-ship approach allows greater flexibility and partial electrification at higher battery costs, (ii) optimal speeds increase and vary depending on the route segment with battery-powered propulsion, and (iii) battery uptake is more sensitive to battery costs than energy density. We hope these insights promote research into the technical feasibility of the off-ship approach.