Those are some big numbers. It makes me think of a crazy thought experiment:
How many MW could a container ship carry by literally shipping energy stored in batteries?
As in they fill up entirely with batteries, sail to a desert, plug into a cable to charge on cheap solar, charge up, sail to a population center, plug in to discharge. Repeat.
That's easy to work out from the parent comment. They conclude that 16,000 tons of batteries are needed for propulsion, with a total capacity of 3GWh.
For a typical 40kton cargo ship, that leaves 24,000 tons for more batteries, for a energy cargo capacity of 4.5GWh. The average US citizen uses ~770,000 BTUs of energy per day, or 0.23MWh. This "energy cargo" of this ship would provide the entire energy needs of a city of 20k people for one day. (I am being a little unfair, by assuming that everyone uses electricity for all of their energy needs in this scenario).
I think there are some startups working on cargo train "tankers" in the US too.
An idea I had after seeing the tanker concept was to have the battery carrier also serve as a generator via wind power. If its a huge ship I suppose you could just stick a turbine on it and go where the wind is blowing. I think a more fun concept is generating power off of a smaller scale cat- or trimaran generating both propulsion and power by sailing conventionally.
At 170Wh per kg (and ignoring the weight of the containers and any safety considerations), 20GWh of lithium battery would weigh 120,000 tons. This is a lot more than a typical Panamax DWT of 60,000 tons, which also needs to include the ship's fuel, provisions, crew, etc.
How many MW could a container ship carry by literally shipping energy stored in batteries?
As in they fill up entirely with batteries, sail to a desert, plug into a cable to charge on cheap solar, charge up, sail to a population center, plug in to discharge. Repeat.