I don’t really buy this argument. Maritime alternatives like hydrogen fuel cells and biodiesel seem like far more realistic plays than installing nuclear reactors on thousands of vessels.
Biofuels is also severely limited in supply and will in the future most likely be reserved for aviation, which is a lot more constrained than shipping etc. when it comes to which fuel options can be retrofitted on existing systems.
Realistic fuels that are being used now: 1. Methanol. 2. Liquid methane.
One could get (much) higher efficiency by using the heat from a nuclear power plant directly (never producing electricity) but I guess that would have to be a completely custom design.
If you have spare electricity (from any source), it's easy. Just capture some CO2 and react it with hydrogen with specific catalysts and at a high pressure. You can get methanol directly this way.
It's more expensive than fossil fuels at the current prices, so nobody cares.
Liquid methane is essentially the same as LNG, which is rapidly becoming the most popular fuel for newbuild ships today. But it's about as environmentally friendly as building natural gas powerplant to replace coal - a temporary solution at best.
Future solutions need a carbon-free fuel, period.
Methanol is slightly preferred because methane can leak, and it's a more potent greenhouse gas than CO2. However, even most of the CH4 leaks happen near the drilling wells, and in pipelines. It's unlikely that synthetic CH4 will have to be transported over long distances.
https://gcaptain.com/aet-orders-worlds-first-ammonia-dual-fu...
Ammonia fueling infrastructure does not exist, and its failure scenarios are just not going to be acceptable. Meanwhile, LNG fueling infrastructure is rapidly getting built out.
What's worse, ammonia is also produced from natural gas, it's used for process heat and as a hydrogen source. There's pretty much no "green ammonia". So instead of round-tripping through ammonia production, it's easier to just burn the LNG directly.
In future, we can switch to green ammonia, but then we also can use power-to-gas or power-to-methanol instead. Both are more efficient than ammonia synthesis.
Methanol production, in particular, can potentially scale down to very small facilities. In theory, large utility-scale solar or wind farms can have a methanol synthesizer unit, that will produce it when there's more electricity when needed. It can then be transported by regular tanker trucks.
Proliferation will always be a risk with nuclear reactors. We will never have nuclear powered civilian ships, as long as there exist pirates out there. Sure, Russia operates nuclear powered ice-breakers, but there are no pirates in the Arctic Ocean, plus, for Russia the distinction between civilian and military is not all that clear.
As for hydrogen, I think ships are the killer app. High pressure tanks or cryogenic tanks benefit from the square-cube law. If you want them to be economical, they need to be really large. They will never make sense for cars, or even trucks, but they can make sense for trains, and certainly for ships.
Wasn't one of the promises of thorium reactors a much lower risk of non-proliferation? (Here's a fun question, can one make a pebble bed reactor design with pebbles designed such that if a ship sank, could a special magnetic sphere of a 'correct' size pull in the pebbles but keep a safe distance? IDK but trying to think outside the box here...)
I think it's worth remembering that for the sake of many ships, we do not need the power-density of an SXX or even an AXX per-se.
> As for hydrogen, I think ships are the killer app. High pressure tanks or cryogenic tanks benefit from the square-cube law. If you want them to be economical, they need to be really large. They will never make sense for cars, or even trucks, but they can make sense for trains, and certainly for ships.
The bigger the tank, the more rigorous the inspection has to be to avoid risks due to hydrogen embrittlement.
I'll admit, I'm -less- worried about that property on a train than a ship, but on a ship I think we'd first need to see good evidence we can maintain things of such size on ground safely.
We might actually get more "nuclear powered" civilian ships, in a way. The reactors will be on land, where they can be properly guarded. And the heat and power will be used to manufacture carbon-neutral liquid fuel.
We gotta remember what a lot of the Marine world really looks like, under the covers.
That is, lots of them will use HFO aka Residual Fuel oil or 'bunker fuel'.
Switching to Biodiesel? Probably the 'cheapest' of the options, not sure what if any implications exist from the switch (lots of ships will stop burning HFO in ports and switch to more common diesel/etc, however not sure if there is a difference in some engines with doing so long term)
Hydrogen Fuel cells are likely as much of a 'refit' from a labor standpoint as switching over to a nuclear reactor; Also the general issues of hydrogen embrittelment and the like have not yet been solved AFAIK especially for the volumes needed for large ships, also not sure if there have been a lot of studies as to whether the hydrogen embrittlement problem could lead to larger structural integrity issues on such a vessel.
Nuclear, OTOH, has had at least a few 'non-military' ships (mostly nuclear icebreakers) with good success.
The current 'whitewashing' strategy of cruise lines is LNG, for whatever -that- is worth...
Edit: finger slipped and hit post too early, so a bit was added, apologies!