It would be amazing if they could leverage the container system, but instead of goods, there'd be battery containers they could just plug in to the ship. You could even charge a battery container somewhere and bring it in by (electrified) rail.
If we ever end up doing that it would mean terrible things for the state of our regulatory landscape.
A completely optimized high capacity cargo rail line can move 500 rail cars per hour. That's 1000 FEUs if we double stack containers. A lithium battery system in a FEU has around 2 MWh of storage. So that rail line has 2 GW transmission capacity if we saturate it with batteries - the same as a single high voltage transmission line. Being unable to build one of those in parallel to the rail line would be extremely sad.
Note that 500 rail cars per hour is actually an impressive feat of logistics. A normal rail yard at a port would be very happy with a sustained rate of 200 rail cars per hour, and will frequently drop below that.
