> The researchers analyzed US-flagged ships less than 1,000 gross tonnage, which includes primarily passenger ships and three types of tugboats.

This is the buried lede. They are excluding basically all cargo shipping.

- Very little of the shipping industry is US-flagged. Most commercial ships sail under flags of convenience such as Panama and Libera, because of their reduced regulations and costs.

- Nobody carries cargo any distance in vessels of less than 1000 gross tons, because that scale would be uneconomical to operate. Modern seagoing cargo ships have about one crew member per 8000 tons of cargo.

> Very little of the shipping industry is US-flagged.

That's true for international shipping, but for shipping between U.S. ports, the ships have to be U.S. flagged due to the Jones act.

https://en.wikipedia.org/wiki/Merchant_Marine_Act_of_1920

I agree though that focusing on small U.S. flagged ships is not very representative of shipping in general.

It could be the ships they are studying are the most inefficient, and pollute the most near people. Maybe they make the most sense to electrify. It could also be the only ones that can be forced to electrify by law.

Large container ships are pretty efficient and mostly stay away from populated areas.

Hah, if we're only going to talk only about tiny US ships, run them on whale oil for all I care.

Seems to me the 80/20 here would be to attack the problem near the top of the stack, not the bottom. Those massive heavy fuel oil burning container ships that basically just smog the ocean 24/7 might be a good target for improvements; as well as just general code enforcement.

Until we can find a battery with the energy density of fuel oil, then it isn't possible to transport sea cargo on batteries.

Fuel oil is approximately 80x the energy per KG when compared to lithium.

Although the US isn't a member of one of the various large port state organisations it is enormous, and it has a lot of coast, so the US Coast Guard effectively acts as a Port State Control authority the way that say the Paris MOU or Tokyo MOU do, but with potentially less friction because instead of Spain and Germany or Japan and Australia having to agree what happens it's just Florida and New York, which are ultimately both responsible to the US Federal government.

If you have a Port State Control regime then the Flag State Control doesn't matter so much and so while it's true that most of these ships do not fly a US flag, they're not really sailing under a foreign flag for the reason you expect. A big reason instead is that these states have an Open Registry, which means everybody in the world can put a ship on their register. To fly the US flag, the ship's owners must be Americans.

Why doesn't Flag State matter so much (if you have PSC) ? Because the port states in effect control regulations if you visit their port, and unless your vessel somehow makes sense just pootling around in the ocean forever you will want to visit a port and thus be subject to their rules. Now, if that port doesn't have Port State Control, which fifty years ago none of them did, the Flag State is the only authority, but in 1978 the Europeans are agreeing rules to protect workers on ships in their water when blam - a shipping accident off the French coast causes world headlines. So of course journalists want to know, you're agreeing a treaty, how will your treaty fix this? And the bald answer for the intended treaty text was "It makes no difference, fuck off". But there are international journalists up in your grill and you've been telling everybody how important your treaty is and so... Port State Control, the Paris MOU is signed a few years later to formalize how Europe's states will coordinate to police everybody, regardless of the flag they're flying, if they enter a port.

The Paris MOU was a huge success, and soon anywhere with money imitated it. Tokyo MOU, there's a Carribean one, Indian Ocean, Black Sea... Anywhere you'd actually deliberately sail cargo ships to has Port State Control these days.

So yes, this does exclude all the cargo shipping, but not really because of the flag, it's because the cargo ships are enormous and so fall out of the size restriction.

~40% of cargo tonnage is moving fossil fuels (coal, oil, gas) around [1] [2]. I would expect this volume to decline as the global energy transition continues to ramp. China's economy and EVs are already depressing global oil prices [3] [4] [5], for example. Also consider global decoupling and repatriating of supply chains [6] [7].

My analysis: We're potentially going to require much less marine transport capacity in the future. How much of that can be electrified is the question, imho (versus "green ammonia" produced from low carbon energy [8]).

[1] https://thelastdriverlicenseholder.com/2022/01/12/almost-40-...

[2] https://unctad.org/system/files/official-document/rmt2019_en...

[3] https://www.iea.org/commentaries/china-s-slowdown-is-weighin...

[4] https://theprogressplaybook.com/2024/09/18/chinas-ev-and-hig...

[5] https://www.energypolicy.columbia.edu/chinas-slowing-oil-dem...

[6] https://www.axios.com/2024/11/14/companies-global-trade-chin...

[7] https://www.bain.com/about/media-center/press-releases/2024/...

[8] https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

Id guess its because large oceanic shipping ships have incredibly fuel efficient engines and batteries cant compete since they're recharged with thermal plants of similar efficiency.