https://www.wartsila.com/marine/products/engines-and-generat...
But I have my doubts. There's still no economically viable way to produce "green" ammonia at scale. It's hazardous to handle and less energy dense than liquid hydrocarbons.
We already have an entire, scaled up industry of producing artificial fuel in a non-petrochemical route: It's where the ethanol in your gas tank comes from.
Farming will be easier to electrify than shipping, or it might not even need to be, and then we will have ample supply (at least here in the US) of energy dense fuels produced through non-petrochemical needs
Growing corn to turn into ethanol to burn isn't like, a carbon negative process right now, but it's also viable today to provide energy dense fuels in a sustainable way to feed our needs like long term storage, compactness, emergencies, and things like planes which won't work with batteries very well.
We already supply enough artificial hydrocarbon fuel through that process to make up 10% of all gasoline burned. As american cars electrify, the corn farmers are going to lose their shit about this subsidy being reduced, so we should just turn it around and have them commit to a larger artificial fuel industry. Our corn growing is already basically a fully socialized industry, let's just lean into it more. Put less corn syrup into random foods like burger buns and put more of it into vats to get energy dense fuel.
It's (technically, barely) an energy positive process, is extremely scalable, is fairly old "tech" such that it won't be owned by one company or country, and the hardest part will be replacing the petrochemical fertilizer.
Oh, ethanol is a more energy dense fuel too.
Regulation is not always bad.
Also, we’d need to make them impossible to open and impossible to remove without cutting the ship in half.
Ethanol as a fuel is mostly a subsidy for US farmers. The net energy gain is low.[1] Ethanol plants need a lot of heat energy to process corn into ethanol. They don't burn their own ethanol for heat; they use natural gas or even coal.[2] If they made their own process heat, which they could, they'd use about half their own output. They wouldn't get the subsidy on that. So they burn other fuels to make ethanol.
That doesn't include the costs of farming the corn.
[1] https://energy.sustainability-directory.com/learn/how-does-t...
[2] https://www.researchgate.net/figure/Energy-use-in-each-of-th...
The point is not an energy positive process. The point is a semi sustainable industry for making high density (liquid) fuels for the few systems that will need that energy density to continue functioning in an electrified future. The goal isn't "Don't burn anything ever". The goal is "Stop adding carbon to the atmosphere"
People talk about that concept like it's the future, but humans have been bulk producing a high energy liquid fuel with good stability and toxicity properties for millenia! The US produces enough ethanol to totally replace our entire commercial aviation usage right now.
Ethanol costs about $2 a gallon at that current industrial production level.
Actually that gives me pause. What stops anyone using it as a primary fuel right now if it's so cheap? I imagine the average airplane jet turbine has done a lot of testing on ethanol of course, and you always have to worry about your employees trying to drink your fuel then.
But my point is; We subsidize corn growth so that the USA will never, ever, ever experience a famine. That's the point. The corn will be grown regardless, and if there isn't a minor societal collapse that year, we should turn more of it into ethanol instead of corn syrup. Electrify agriculture and industrial process heat and you can also use that setup to essentially "Load shift" the high solar output in the summer into the winter.
You still have to deal with a lot of specialized infrastructure and engine design.
I would have thought something like processing coal or synthesizing ethanol to a more suitable drop in replacement fuel would be easier. Maybe less scalable or outright requires more energy input.
Is that really such a downside? Ports are full of specialized infrastructure anyway, and the costs of engine design can be amortized over many engines to be quite minimal overall. Once you've done the design work an ammonia engine isn't more expensive than a hydrogen or diesel engine. And the upsides of ammonia are substantial: fairly easy to handle, quite energy dense and most importantly it is already produced worldwide in huge amounts.
You should probably check who would control a larger part of the ammonia supply. I can see few other reasons for putting large quantities of something so unforgiving as ammonia on ships.
NH3 has no carbon in it. It has the advantage of not producing CO2. This is a good advantage for public communication.
Methane works perfectly well for shipping. It's cheap, abundant, and we already have all the infrastructure for it.
And to fully decarbonize it, we'll just shift to biogas or power-to-gas.
There is nowhere close to enough biogas for ocean going vessel. Methane has got into the focus due to methane slip. And fossil methane only allow a limited CO2 reduction vs Marine Diesel oil. It won't be enough to reach 2030 IMO target on CO2 reduction.
The total amount of biogas production is around 2.5 exajoules (2.5*10^18) per year. The amount of diesel used for intercontinental shipping is 213 million tons, or 10^19J (given the 45MJ/kg energy density).
So we need about 4x the current biogas production. That's entirely doable, especially with the power-to-gas transition.
These large ships will likely be de-carbonized either with ammonia turbines or fuel cells. Mann has already been running a PoC ammonia turbine ship for about 4 years--the last 2 undergoing proper blue-water "sea-trials" journeys.