I wanted to offer some math on the *economics* of electrified container ships. This @VaclavSmil article does a good job of describing the technical challenges, but doesn't get into cost/benefits, which I think is important here. https://spectrum.ieee.org/transportation/marine/electric-container-ships-are-stuck-on-the-horizon

In the article, he notes that a large trans-Pacific container ship would have to be 40% batteries, which he sees as a deal-killer. He should have priced it out, because that wouldn't be a problem if the ship were cheap enough. However, it isn't cheap enough under current prices.

Let's do some math using Smil's numbers. His large-scale trans-Pacific ship needs 4650 tonnes of diesel. At $550/tonne, that is $2.5M of fuel for one trip. He says that you would need 30 GWh of batteries for the same trip (though only 60% of the cargo). At $15/MWh, that is $0.5M.

So, good news: you save $2M per trip, or $1.7M to ship the same amount of stuff with electric (when adjusting for the cargo capacity).

But now the bad news: 30 GWh is a lot of batteries and they aren't cheap. At $200/kWh (a very good deal), the batteries cost $6B upfront.

So, as far as a payback period, it would take 3,000 trips to make the energy cost savings add up to the cost of batteries. And those trips take about 1 month. 3,000 months = 250 years. Not a great payback period. And we are taking only 60% as many containers each time.

Smil notes in the article that shorter trips may make more sense for electrification. For example, a trans-Atlantic ship might run half the distance in half the time, needing half the batteries. Not the ship can manage 80% as much cargo, needs $3B of batteries (ooof) for 15 days.

It only saves $1M per trip now, but that makes the payback period $3000M / ($1M * 24 trips/yr) = 125 years. Still pretty terrible, but we can see how the scaling works: half the distance/time, half the payback period. If the trip were 1 week, payback is down to 60 years.

So, in short, it is hard to see this penciling out, even for super-cheap batteries (going down to $100/kWh reduces the cost/payback period by 50%). So it seems like large-scale, long-distance shipping is stuck with diesel, or goes to fuel cells/nuclear if decarbonized.

At the same time, there is space for short-distance electrified ships (ferries, for example), because you don't need much stored energy and can charge frequently. I also imagine that cruise ships would be a good target, as they spend half a day or more in port every day or two.

But successful application for ferries cannot easily scale up to long-distance container ships. So if you had a vision of ports becoming giant battery repositories and providers of large-scale ancillary services, I don't think the math supports that as particularly likely. Sorry.

PS: I started into this math with the hypothesis that electrification was pretty feasible for shipping, but math convinced me otherwise. Obviously, we could force it to happen, but it sens to me like that will be awkward/expensive for decades to come.

PS2: I had a vision of modular batteries in Conex containers that could be traded out in ports (easy with the conex-handling equipment), and ports acting as hosts to huge battery banks that charge during high-RE periods and supply services. But alas: