[otherotherchris]

Most diesel and natural gas reciprocating engines can be switched to ammonia with only changes to fuel pumps and injectors.

It's a great easily transported bridge fuel that can replace LNG export until the anti-nukes pull their heads out of their arses.

[KennyBlanken]

You misspelled "replacement of the nearly the entire fuel system."

"Easily transported"? Are you nuts? It has far less chemical compatibility than LNG and is wildly more dangerous to people. It gets even worse if the ammonia has any impurities.

Ammonia is highly corrosive to zinc, brass, and copper. Copper, for example, is often used as crush washers in high pressure banjo bolt fittings used in oil and fuel lines in automotive applications.

It's wildly incompatible with several elastomers (ie fuel lines and seals) and plastics (fuel tanks, sensors, tubing, etc.)

If there are impurities in the ammonia, it starts eating the shit out of steel, too.

I doubt existing emissions control equipment would work.

Then there's the small problem of what happens when any unburned ammonia makes it past the rings into the crankcase....so the entire evap system now has to have ammonia-compatible parts...and since the evap system vents into the intake system, which is often made with lots of plastic, now you've got to replace the intake manifold. And since the oil is going to get contaminated with ammonia, the entire oil system has to have ammonia-compatible parts, too.

In modern direct injection vehicles (diesel or gasoline) you're likely at a huge number of components that would likely need to see ammonia-compatible equivalents developed, manufactured, tested, and then installed on the vehicle. The high pressure pump on most passenger vehicles is driven off a cam and tightly integrated into the engine, for example. It's not just a matter of "swap out the fuel pump." Fuel tanks in passenger vehicles are often plastic and not trivial to remove, at all.

Oh, and: renewable energy sources are significantly cheaper than nuclear, which is why wind and solar are replacing decommissioned nukes at a ratio of 6:1.

You seem a bit outside your lane.

[otherotherchris]

>"Easily transported"? Are you nuts? It has far less chemical compatibility than LNG and is wildly more dangerous to people. It gets even worse if the ammonia has any impurities.

Why would there be impurities in ammonia generated from solar powered water electrolysis? Where are they coming from?

Why would clean NH3 react strongly with carbon-managanese steel pressure vessel used in LNG transport?

>I doubt existing emissions control equipment would work.

Is emissions control installed on large marine diesels and stationary generation in Japan?

>In modern direct injection vehicles

Bzzzt. Wrong. This article is about coal power.

[rini17]

Water is such an impurity. Even diesel system can have problem with water condensing out of air during day/night cycle if no precautions are taken. And diesel won't react with water but ammonia will and very eagerly.

[ncmncm]

I doubt anybody seriously thinks ammonia will be a fuel in cars.

But is practical for ships and peaker plants.

[solstice]

Really interesting. Could you post some sources?

[jandrese]

The only downside is that you're dealing with ammonia...

I'm dubious simply because ammonia is so nasty to human life. Spills are far worse than diesel or even gasoline spills.

[neltnerb]

Yeah, ammonia and hydrogen as ways to store energy have significant challenges, they probably aren't worse than if we had to store natural gas. Ammonia is corrosive and needs to be cold, hydrogen needs to be compressed to be energy dense so it needs heavy walls. Both explode. Hydrogen leaks a lot around seals and through them, but welded tanks probably do fine.

Natural gas needs to be compressed to be energy dense as a liquid, it explodes, it maybe has some technical advantages but the benefits seem narrow if you're starting from a fresh analysis. We're good enough at it to switch to an ammonia economy, people handle it safely all the time. It's just different risks.

[Reason077]

Natural gas is fairly safe (non-explosive) while compressed. It has to decompress and reach a pretty specific ratio of air-methane mix before it becomes explosive.

Hydrogen, by comparison, is explosive across a much wider range of pressures and concentrations.

Hydrogen also needs to be stored at far higher pressures than natural gas in order to reach comparable energy density, which makes it more difficult and expensive to handle and transport.

[ncmncm]

We will not be using compressed hydrogen, so that doesn't matter. LH2 is kept at atmospheric pressure.

[Reason077]

Liquid hydrogen is also pretty difficult and costly to store and transport, because it requires cryogenic storage. You need to make sure to keep it at −252.87 deg C or it's not going to stay liquid for long! It also takes a lot of energy to compress into a liquid in the first place, making it much less efficient as an energy carrier.

Hydrogen used to get used a lot by the space industry (Space Shuttle, etc), but now days the modern rocket industry has been moving to other fuels (kerosene, methane) - largely because of the greatly reduced costs of handling those fuels!

[ncmncm]

We are already quite well practiced in handling and transporting liquified methane, which in only incrementally easier than LH2.

Rockets are lately designed for methane in large part so that concentrating Martian atmosphere for fuel will be more practical, but also for CO2's greater molecular mass, important in an earthly first stage launcher, which needs absolute thrust, to get moving in 1G, much more than efficiency.

As fuel, LH2 may find use mainly or even exclusively for aircraft, but it is exceedingly valuable as feedstock for other work, including ammonia and, yes, methane synthesis. Methane is itself feedstock for many other processes. Ideally these would not result in released CO2...

[ncmncm]

Hydrogen will not be compressed, but rather liquified.

Hydrogen is prevented from exploding by assuming all joints leak, and providing continuous positive airflow to keep concentration always below 5%.

[coderenegade]

Methanol is probably better than ammonia as a vector for green hydrogen. It carries less hydrogen per volume, but it's a liquid at room temperature, trivial to transport, and it's generally less dangerous. It's also been used as a fuel for reciprocating engines for more than a century.

[japanuspus]

Methanol and ethanol share the same fundamental problem: they are both carbon-based, and despite global warming atmospheric CO2 is still well below 0.05% of the atmosphere which means it is very resource-consuming to extract it. As long as we still use some fossil fuels, you can capture at power plants, but in the long run it is a dead end.

Ammonia, on the other hand, just requires nitrogen which is 70% of the atmosphere and very easy to extract in industrial quantities.

[coderenegade]

You don't need to extract CO2 from the atmosphere using direct air capture (I agree that it's a dead end); you use existing sources of waste to intercept the carbon cycle. Sewerage, for example, contains carbon that was pulled from the atmosphere by a plant, or bacteria in the soil. Ditto for municipal solid waste, especially wood products and paper. If you need additional sources, you can grow fast-growing plants (seaweed is preferable, since it doesn't rely on good land) to pull carbon out.

When you make methanol, processes like gasification and pyrolysis leave you with excess carbon in the form of carbon black, or ash. If you sequester this before it oxidizes, fuel production becomes carbon negative. Methanol is better than ethanol because a) you can't drink it, b) the single carbon molecule means it burns cleaner, c) you get more fuel for the same initial amount of carbon, and d) it doesn't compete with food production for arable land.

[zardo]

And the emission control system.