It’s pretty much irrelevant. You can stack containers vertically easily, and height difference doesn’t matter that much (8’6 vs 9’6 are the two common sizes). Below deck you have a hard cap because of hatch covers, but above deck you’re only really capped by sight lines. Lengths are 20ft and 40ft, so differ much more, and so having TEU or FEU as measurement is much more useful.
Super interesting. I recall a company in Thailand doing that for scooters. They had a wall exchange where you just drop in your old battery and get a new one. Real plug and play. This is obviously way more intricate though.
There is a company in Taiwan called Gogoro, which created this market; they sell scooters that you can't charge, but they have modular batteries and battery swap stations all over the island.
You just stop at any station, insert your depleted batteries, click a button on the app and they give you freshly charged batteries to put back in and go.
That makes a lot of sense when you think about it. Container ships are always stopping to load and unload containers in ports. Both the ship and the port already have infrastructure for handling containers. They also have infrastructure for handling refrigerated containers which need electrical hookups. This likely needs more specialized electrical hookups for charging and discharging, but that’s an incremental change rather than a whole new thing.
It does make sense. The problem is scale. There is an inland barge in the Netherlands that does this with 4 20ft battery filled containers, capacity is about 200TEU if I remember correctly.
The problem is charging. Charging up 4 containers worth of batteries takes a wild amount of power, we’re talking multiple orders of magnitude more than refrigerated units. By my calculations you needed about 100 days of charging on a single reefer plug. Ofcourse you can speed that up with custom charging infra, but still, the amount of total energy needed is mindbogglingly large and won’t scale easily to ships of 20 000 TEU, or even just constant visits of these 700TEU feeder ships.
If you use fast chargers you can not only charge them quickly, but you could prefer charging them when electricity is cheaper than normal (when the wind is blowing out the sun is shining.)
It can actually help with the intermittent nature of renewable electricity.
The port would need to seriously upgrade their electrical connectivity, but there’s an incentive to the grid operator as well.
Does not matter if you can’t move that much power to container terminals. You presumably don’t want to put a nuclear plant in every port. Even if you consider the battery problem to be solved at scale, you just don’t quite appreciate the enormous energy consumption of these ships. Charging them with existing infra used for refrigerated container is a fiction, plain and simple. You’re off by 2 or 3 orders of magnitude.
This is one area where we’re guaranteed to see a fuel being used. Either synfuels, e-fuels, ammonia, hydrogen, etc., it will have to be something that can be carried into the port from elsewhere. There’s no other way around this problem.
If nuclear were cheap enough to do that, we’d just put the reactor on the ship.
Note, I’m not suggesting you could use the existing infra for refrigerated containers, but I am pointing out that containers that need an electrical hookup are not novel. The difference here is the current supplied via that hookup.
“Battery in a shipping container” systems today can supply somewhere between 1-4 Megawatt hours of energy. If the ship has two 900kW motors, then you get about 30 minutes to two hours of propulsion per container at ahead flank and under ideal conditions.
I suspect these ships stop fairly frequently, maybe once every few hours or once a day? I read once that containers can be loaded/unloaded at a rate of about one per minute, so “refueling”, so to speak, becomes a 5 minute to one hour job, depending how much energy is needed. I wonder how competitive that is with current ships of similar size.
The economics become better as energy density of the containers improves, for sure, though.