According to Wikipedia:

Emma Maersk uses a Wärtsilä-Sulzer RTA96-C, which consumes 163 g/kW·h and 13,000 kg/h. If it carries 13,000 containers then 1 kg fuel transports one container for one hour over a distance of 45 km.

You already have to elevate each of those containers (with the train or truck from the coast). An electric elevator would be much more energy efficient than the current solutions are. A litter or so of diesel fuel of electricity per container. Less than 100 kilometers of shipping. Much less than 1000 kilometers of trucking.