New York City to Lisbon is 5,400 kilometers. So no, 2,800 km is not even far enough to cross the Atlantic let alone the Pacific.

That submarine also does not use batteries for energy storage, it uses hydrogen gas (almost certainly produced via steam reformation).

That sub cals uses fuel cells, because WW2 is over for quite a while and technology advanced.

But no, 2,800 km isn't short. Not feasible for commercial ise, sure, but then no submarine technology is commercially feasible. It is too specialized.

Hence, green fuel as the preferred, and most realistic, option to decarbonize shipping.

Green fuel has proven exceptionally difficult to manufacture, and companies promising to produce it are running far behind schedule: https://www.technologyreview.com/2022/04/25/1050899/promethe...

> ...no submarine technology is commercially feasible. It is too specialized.

Except that's demonstrably false. Many (most?) subs use nuclear propulsion, and there are civilian ships that use nuclear propulsion. The NS Savannah was operated successfully for a decade [1], and several Russian ice breakers for even longer than that.

The fact that organization with the explicit goal of lobbying for renewables [2] prefers green fuel does not make it the optimal choice. It's the optimal choice to advance that group's goal of promoting green fuel, because nuclear power at scale is a competition risk for wind and solar

1. https://en.wikipedia.org/wiki/NS_Savannah

2. https://en.wikipedia.org/wiki/International_Renewable_Energy...

NS Savannah (one has to wonder why nobody mentions the German Otto Hahn, but whatever), was decomissioned for economical reasons. Heck, the only nuclear powered vessels the US Navy has are carriers and subs, even the lastest British carriers aren't nuclear powered anymore.

All in all, besides the niche need of the Russians for nuclear powered icebreakers, there were three civilian nuclear ships: NS Savannah (economical failure), Otto Hahn (likewise and retrofitted with a diesel engine) and the Japanese one (forgot the name, but that was both a technological and economical disaster).

And that is ignoring the fact that naval nuclear reactors are among the most well guarded secrets a nation has, none of that tech will ever see civilian use for that alone (the current generation thaz is, the reactors used in the three vessels mentioned showed already to be unfeasible for commercial use).

Edit: Nuclear power is nowhere near to be a risk for wind and solar, wind alone adds multiple NPPs worth of capacity to the grid every month while the added net nuclear capacity is basically negligible for decades now. Nuclear is not, and won't be, built at scale in the next decades. Only potential exceptions are India (good, otherwise they would build coal plants) and China (purely political, and at the same time Chine is building even solar and wind power than nuclear).

There's also the Sevmorput: https://en.wikipedia.org/wiki/Sevmorput

Even just one example is an infinitely larger fleet of nuclear powered cargo ships than green-fuel powered cargo ships.

Nuclear maritime propulsion isn't exactly a mystery. The basic operating principle of both pressurized water reactors and lead cooled reactors are known. All of the West's main geopolitical rivals (Russia, China) already have nuclear powered submarines - I'm not sure how you think technology for nuclear powered cargo ships are going tip the balance militarily.

This is pointless. The reason no nation on earth will green ligjt the use of it military maritime reactor tech for commercial use simple: this tech is secret and nobody wants the knowledge of said tech fall into opposition hands. ITAR is childs play in comparison.

This means, new reactor tech needs to be developed from basically scratch. And no, the mere handful of Russian icebreakers, and that one cargo ship which is half an icebreaker, don't count. Not if we talk about thousand of commercial vessels in operation.

One last question: Do you think we are faster to develop and build the tech and infrastructure for green fuels (which are needed everywhere from ships to planes) or to develop and build the industrial base to produce hundreds of small scale maritime nuclear reactors (for we don't even have the reactor tech yet)?

Hundreds of maritime nuclear reactors are already in operation. And the technology has already been deployed to civilian ships by four different countries. Your statement that no nation will greenlight maritime nuclear propulsion for civilian use is just factually incorrect. Countries did approve the use of nuclear maritime propulsion in ships. You even listed three examples yourself - you disproved your own claim.

Nuclear maritime propulsion is demonstrably closer to production than synthetic fuels. The former has been used in hundreds of warships and four cargo ships over the span of half a century. The latter is currently only produced using concentrated CO2 from biomass or other industrial byproducts (which is not something available at scale), and are not used for maritime propulsion.

Why is it that, that people always underestimate the technical complexities of thise things.

a) military nuclear technology will never see civilian use, claiming otherwise is beyond naive and ignorant

b) civilian nuclear powered vessels have been tried and deemed uneconomical (no, one specialized cargo ship requiring the power from a nuclear reactor to break through 1.5 m of ice doesn't count...)

- so far a grand total of 600 maritime reactors (see point one for the military part) in history have been built globally, 400 or so of which are still in operation, in order to decarbonize global shipping that is close to the number of reactors needed yearly, and not even the military providers have the capacity to build that many (e.g. the Russians built, what, six of those since 2014!)

You keep hand-waving all of that away...

Again, we have four different countries that built civilian nuclear powered cargo ships. I don't doubt that designing maritime nuclear power for these ships was challenging. But it has already been done. The technology already does exist. The NS Savannah, Otto Hahn, and the Mutsu all used low enriched uranium in their reactors (as opposed to the highly enriched uranium used in military reactors). That's the main challenge in adapting nuclear power to civilian use, and it's already been solved.

By comparison, how many green fuel powered cargo ships have been in operation for over a decade? If hundreds of nuclear powered vessels operated for over half a century is too immature, then green fuel powered ships are even less mature that nuclear maritime propulsion.

You have now idea how ship propulsion systems work, do you?

The reason why I said "green fuel" as opposed to artificial natural gas is because hydrogen and ammonia are also potential examples of green fuel, in addition to artificial hydrocarbons.

Again, how many ships have been operated with green fuel? There are LNG powered ships, but none using LMG produced in a carbon free manner. As stated above, producing artificial hydrocarbons remains out of our capabilities. Existing power to gas prototypes are really just converting biomass to methane and that method is limited by biomass availability . There are smaller prototypes for hydrogen powered ships, but nowhere near the size of the NS Savannah and they haven't been operated for nearly as long. And I can find no examples of an ammonia powered ship.

Again, how many examples of green fuel powered cargo ships in commercial operation can you give? Not fossil fuel powered ships that can theoretically run off green fuel if we hand wave away the challenge of producing artificial methane. But ships actually using green fuel in the same vein that the NS Savannah actually used civilian nuclear maritime propulsion?

See, comment like that tell me you have no idea how a ship engine, or engines in general work. The problem to be solved is not the ships propulsion system, what stupidly keep repeating with nuclear reactors, but the source of the fuel for those engines we already have (developing new engines is happening day in day out, and that development will simply optimize for ammonia or hydrogen based fuels). A question which has almost zero to do with the question you so desperately want to have answered as some kind of, what, childish got ya?

I get it, you area NS Savannah and nuclear fanboy, reality so simply doesn't agree with you, nor do the relevant industries.

> developing new engines is happening day in day out, and that development will simply optimize for ammonia or hydrogen based fuels.

Meanwhile, we already have decades of operational experience with civilian nuclear maritime propulsion. It's objectively more mature technology than green fuel.

And for the record, I do indeed know hydrogen powered combustion engines work. Perhaps you're unaware that by virtue of hydrogen's much hotter combustion temperatures, it's hard to avoid producing nitrogen oxides (a greenhouse gas) as a byproduct in hydrogen combustion engines [1]. Hydrogen fuel cells are an alternative, but those have less power to volume ratios and have never been deployed at the scales required for nuclear maritime propulsion. Not only that, containing and plumbing all this liquid hydrogen is a challenge, too. There's more complexity than you think to make a hydrogen engine that doesn't emit greenhouse gases.

1. https://en.m.wikipedia.org/wiki/Hydrogen_internal_combustion...

You just refuse to get it, don't you? We way more experience eunning everything from gas turbines to ship engines than we have running civilian nuclear powered ships, I hope I don't have to explain how many non-nuclear powered ahip we have, do I?

We also have more experience using biogas to be burned in combustion engines and turbines of any sort, as we do creating said biogas.

We also way more experience in creating sythetic fuels, and using electrolysis to create hydrogen out of sea water (green hydrogen).

Those are all solved problems, and thisbis not my opinion, as opossed to you, but facts confirmed by the very industries involved in ship building and shipping.

Really pointless to discuss with ignorant tech illiterates like you.

> I hope I don't have to explain how many non-nuclear powered ahip [sic] we have, do I?

And again, how many of those are using hydrogen, ammonia, or synthetic methane?

> We also way more experience in creating sythetic fuels, and using electrolysis to create hydrogen out of sea water (green hydrogen).

Absolutely not. Almost all synthetic fuels is using biomass as an input, which does not scale. And only tiny, tiny fraction of hydrogen is produced in a carbon neutral manner. Less than 0.05%: https://en.m.wikipedia.org/wiki/Green_hydrogen

Again, if these are solved problem, show me the fleet of ships powered by hydrogen, ammonia, or synthetic methane.

I love the double standard!

Nuclear technology: if it isn't exactly the same thing we need, no matter how close, it doesn't exist.

Hydrogen etc.: we have a rough analogy and no real way of getting from there to here, therefore it is proven technology.