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Comment by RetroTechie | Hacker News Reader

Not just fertilizer:

"In addition to its use in the fertilizer and chemical industries, ammonia is currently seen as a potential replacement for carbon-based fuels and as a carrier for worldwide transportation of renewable energy."

Long-term grid storage?

Publication: 22 July 2022

Anyone know if maybe some pilot / small scale production facility has been set up in the mean time?

I've read about a farm that produced its own fertilizer, but dunno whether that uses this or some older / unrelated process.

Would be a huge breakthrough in any case.

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Where are all the people that complain about the dangers and impracticality of hydrogen when the topic of using a corrosive gas that poses an immediate danger to life and health at concentrations as low as 300 ppm as a fuel comes up?

They're trying to avoid using the stuff in industrial refrigeration it's so nasty, and yet here we are gleefully considering rolling down the highway with it in the cheapest vessel industry can lobby for strapped to our bum.

I guess the notion has passed so quickly we haven't had time for the media to program us with corporate agendas...

I don't think it's realistic as a fuel for cars, but "worldwide transportation" means more than that. I suspect they're talking about container ships, tankers, and such.

Ammonia is easier to liquify than hydrogen, and is in many respects easier to handle. However, it's definitely not something you want to have a spill of at a gas station or in your garage, and for that reason, it probably won't have "consumer" uses.

As far as industrial gasses go, it's certainly nowhere near the worst, and there's plenty of ammonia tankers on the roads today, but large spills do kill people every now and then.

It is certainly easier to liquefy, I can't argue that point.

Hmmm, "gas station filled with petrol that explodes" vs "gas station filled with hydrogen that explodes".

Being near either one as it explodes would be bad, but I wonder which one looks more impressive movie-effects-wise? :)

In my limited understanding, neither one really explodes. The petrol one would look like a huge impressive fireball that launches a big black mushroom cloud and then just burns like crazy. The hydrogen one, if the hydrogen is fairly pure, would be like a big faint blue wispy fireball, not all that impressive.

If there were an oxidizer in the mix somehow, it would be rather more explosive.

Cool, thanks. :)

The issue with hydrogen is that it has a fairly wide combustion range (meaning the ratio of fuel/air that can burn), I can't remember the numbers but it's several times greater than other common fuels. The other issue with hydrogen is that the combustion happens VERY fast... if you ignite gasoline vapor/air in an open 5-gallon jug, you have a nice rocket that'll fly 50 feet or so. If you ignite hydrogen/air in the same jug, you have permanent hearing damage and shards of plastic embedded in you.

If the hydrogen is fairly pure and the amount is question is small, then sure: combustion will happen at the hydrogen-air interface. If it mixes with air before ignition, then it can burn all a once, and Wikipedia informs me that “the limits of detonability of hydrogen in air are 18.3% to 59% by volume.”. Yes, it will literally detonate with supersonic flame velocity.

I once got to watch some moderately crazy students fill an ordinary party balloon with a stoichiometric mix of hydrogen and oxygen at ambient temperature and pressure. When it was ignited, the result was extremely impressive. No one was injured (because we were all warned to protect our ears and open our mouths and balloons don’t produce significant shrapnel), but the shock wave was not at all subtle.

https://en.m.wikipedia.org/wiki/Hydrogen_safety

Why is having open mouths important?

Less pressure on your eardrums if the shock wave reaches them from both sides.

Ah. So holding my eustachian tubes open (half way through a yawn) would also be a good idea?

My dad did this once. He drained the acid from a car battery and put it in a container with a narrow opening, then dropped in a bunch of zinc galvanized nails. Sulfuric acid + zinc = hydrogen gas. He then stretched balloons over the mouth of the container to inflate them, tied them up, and attached a strip of newspaper to the bottom. Finally, he lit the bottom of the newspaper on fire and let it go. Balloon floats up, makes pretty fireball.

We ran into two problems. First, a number of the flames blew out on their way up. No fireball.

Second, we ran out of balloons pretty fast. So he cast around for ideas, and decided to fall back on a box of condoms. They held a lot more hydrogen than the balloons.

They were also equally likely to go out before blowing up. I always imagined them coming down on someone's lawn, causing no end of confusion.

[DO NOT TRY THIS AT HOME! And if you're tempted, there's one thing I left out that's necessary for it to work properly, and the only thing I'll say about it is this warning: https://sciencenotes.org/add-acid-to-water-or-water-to-acid/ ]

That’s not the same thing, though — your dad forgot the oxygen! A balloon full of approximately pure hydrogen makes a nice fireball but doesn’t really explode — the same group that made the exploding balloon I watched also did one of those.

The stoichiometric premixed balloon is only 2/3 H2 by volume, so it releases 1/3 less energy, but it’s a whole different experience when the energy is released essentially all at once. Interestingly, there was no noticeable fireball from the premixed balloon.

A premixed H2+air balloon probably makes a fine explosion, too :)

> That’s not the same thing, though — your dad forgot the oxygen!

Oh, I'm quite aware. The other fun game we played was with his acetylene welding torch and balloons. It has separately controlled tanks of acetylene and oxygen. Acetylene only = nice big fireball. Acetylene + oxygen = no fireball at all, instead a very loud boom + a bit of a shockwave.

A quick search for higher heating values suggests that acetylene and hydrogen gasses have fairly similar HHV per mole of oxidizer. (H2 needs 1/2 equivalent or O2; acetylene needs 5/2 equivalents, so H2 wins by a bit.)

But H2 takes up most of the space in the balloon, and acetylene is nice and compact, so considerably more total energy should be available with acetylene!

I don’t know whether oxyacetylene will detonate nicely, though, or whether a balloon-sized oxyacetylene mix will merely combust subsonically.

Hydrogen is way worse than gasoline or any hydrocarbon. It has to be stored at very high pressures and there’s no practical situation in which it doesn’t explode.

Toyota have produced a prototype ammonia engine they claim is the end of the EV market.

Neat. I look forward to them rolling out a production model in 2043.

I look forward to them rolling it out downwind.

They can keep making claims to cover up their complete bungling of their market position.

As for the idea itself. Ammonia as fuel fails the first principle of safe design. It’s a poisonous gas. Using it as a fuel is a willingness to trade the safety of people for a cheaper fuel.

The move from cars to SUVs in America was so car manufacturers could skip emissions and safety requirements of cars on the technicality that SUVs are “light truck” chassis[1]. Dan Luu shows that those safety regulations are often a box ticking exercise for manufacturers except Volvo[2]. American stroad design is a particularly bad mix of street and road which is more dangerous for drivers and pedestrians than other designs. And the diesel emissions scandal so many car manufacturers were caught defrauding.

“willingness to trade the safety of people for a cheaper X” is exactly what we should expect car companies (and companies in general) to do, because that’s what they’ve done so often though history.

[1] https://youtube.com/watch?v=jN7mSXMruEo “These stupid trucks are literally killing us” -NotJustBikes

[2] https://danluu.com/car-safety/

https://www.enginelabs.com/engine-tech/engine/corrosion-of-c...

It is important to note that hydrogen, due to the small size of the molecule, is really hard to contain as a gas. Moreover, leaked hydrogen gas is an indirect but potent greenhouse gas via interfering with the degradation of existing methane in the atmosphere. If we leak enough hydrogen, we might not be helping the climate very much.

I was once in a presentation which claimed formic acid to be a better alternative, but I'm not an expert in that field, so I can't comment on its merits.

There were some recent articles suggesting that there may be enough natural hydrogen seeping out of the ground to supply all of humanity’s energy needs. It seems a bit unlikely that leakage of hydrogen from fuel systems would matter much in comparison.

How about radon, is that fissible?

No, it gives off alpha particles and gamma rays. Hypothetically, you could build a device to harvest that energy (along the lines of an RTG), but the energy density and conversion efficiency would be laughable, given the 3.8 day half-life and gaseous state.

To be clear, I’m saying enough hydrogen to power humanity chemically, not by fusion.

Enough hydrogen to power humanity by fusion is readily available anywhere :)

Use compressed air or NOx as oxidizers for delayed combustion in engines. Not only would it provide a means of storing energy for ICEs, but it would also eliminate pumping losses on the intake stroke.

I wonder if this process would be easy enough that “ammonia battery” plants would just synthesize on site when solar power is high. Like charging up a battery with no need to move anything.

Or maybe a regional factory with short pipelines.

At atmospheric pressure Ammonia liquifies at −28 °F (−33.3 °C), Hydrogen −423.17 °F (−252.87 °C). That alone is a vast improvement. You can build a car/boat/aircraft that keeps its Ammonia fuel tank cool with minimal effort however it’s wildly impractical with hydrogen.

Add the issues with hydrogen embrittlement and Ammonia starts to look trivial by comparison. People deal with industrial quantities of Ammonia on a regular basis without significant issues. Hell even gasoline and diesel are toxic and can be quite dangerous

https://www.nbcchicago.com/news/local/attempt-to-pass-a-tank...

No, they have significant issues on a regular basis still.

Anything dangerous at scale has issues. That doesn’t mean people are unwilling to fill up at a gas station or use other hydrocarbon fuels despite plenty of far worse examples. https://www.npr.org/2021/11/06/1053162519/sierra-leone-oil-t...

And plenty of more recent examples: https://www.fox29.com/news/tanker-truck-fire-closes-stretch-...

Ammonia is one of the most common chemicals manufactured and transported around the world and has plenty of accidents but hydrocarbon accidents get into the hundreds of deaths: 150 dead https://en.wikipedia.org/wiki/Tacoa_disaster 500-600 dead 5000–7000 suffering severe burns https://en.wikipedia.org/wiki/San_Juanico_disaster 167 dead https://en.wikipedia.org/wiki/Piper_Alpha

People even hook up to natural gas lines after events big and small like: 300 dead https://en.wikipedia.org/wiki/New_London_School_explosion or here’s a recent event which destroyed 60-100 homes https://en.wikipedia.org/wiki/Merrimack_Valley_gas_explosion...

My primary point here is that if you see an ammonia spill you're going to die whether or not it explodes.

I suppose it's worth noting in your second link, the fatalities were from the kinetics of the impact, which is a hazard that belongs to "things with velocity" rather than "things containing fuels".

We can assume that uncontained fire and explosion are categorical hazards with fuels.

Ammonia has significant risks that few other proposed fuels present and I believe it's worth considering whether this is something we want moving outside of hazmat routes between industrial zones.

Except the risk of fire / explosion is lower. NFPA 704 for gasoline is 1 Health, 3 fire, 0 Instability where Ammonia is 3 Health, 1 fire, 0 Instability

Major spills of either are dangerous but rare compared to how much is being created and transported. We’re only ~5x as much gasoline vs Ammonia today. Considering most cars would be EV’s I suspect the total amount of Ammonia produced even with widespread adoption isn’t going to change by that much. Say Long haul trucks, heavy equipment, aircraft etc.

PS: Which isn’t to say Ammonia is actually a good fuel, the only thing I can think that actually used the stuff was the X-15. So it would need significant economic advantages to end up adopted.

You don’t have to keep it cool. Ammonia has similar profile to propane. It is liquid at 7-14 bar. We build pressure tanks like that all the time for propane.

Ammonia is probably too unsafe for cars and boats. But anything filled by professionals like trains or ships would work. But might work to have tank exchange system like with propane.

I was thinking about that but it's only a liquid at those pressures if you can keep it from getting too hot--say, a tank sitting there under the desert sun. And if your pressure relief triggers on ammonia it's a lot more of an issue than if it happens with propane.

Pretty sure they're talking about moving energy, not energy for moving.

> danger to life and health at concentrations as low as 300 ppm

Well its not like you can put any petrochemical fuels in you coffee

This is for ammonia inhalation.

I don’t think either is a good fit really, if that helps.

Replace highway infrastructure with train infrastructure that is powered by overhead lines. Build out the power grid to support that, and blanket the country with new rail lines that are nationalized and run as a public utility.

Result, reduces carbon footprint of travel - land shipping - ability to build out modern towns - etc

Toss in a bill to require all train lines to also install national fiber. You now have enabled the revitalization of large swaths of the county.

Especially frustrating when considering that decarbonising a large part of transportation is easy, but boring: it's trains, light rail, it's cycling infrastructure. Not as sexy as futuristic energy sources, but it's what will save us in this sector: viable alternatives to the horrendously inefficient automobile

This is not to mention everything else. The immense death toll directly (crashes) and indirectly (pollution, particulates, etc). The waste of space in cities. The waste of time in traffic that is unfixable if everyone is driving in an individual car. Etc etc. I wish people would stop trying to save the auto industry and start looking at the root of the problem.

Bulk transport, not consumer vehicles

The Haber Bosch reaction does not produce any CO2:

  N2 + 3H2 -> 2NH3

The challenge is getting the zero emission Hydrogen. The process presented here is somewhat better than using electricity for the electrolysis split water, but still substantially more expensive than the gray Hydrogen obtain by cracking Methane gas and releasing the CO2.

Where did you conclude it was somewhat better than using electricity for electrolysis?

I took the author's claim of 100% electrolytic efficiency at face value and contrasted with typical water electrolysis efficiencies, followed by a Haber-Bosch step.

This method of direct electroreduction should not confused with the Laser-induced method discussed elsewhere in the thread, which has abysmal numbers.

The 100% efficiency is faradaic efficiency, not energy efficiency, I believe.

Are there power plants today that burn ammonia directly? If not, is it a simple/cheap enough conversion?

It is actually cheaper because of existing infrastructure that exists for fertilisers manufacturing.

But the main concern is that ammonia burns slowly. It might work in power plants but not in EVs

Why would you want to burn ammonia in an electric vehicle?

Not sure if they are today, but Toyota is putting a lot of effort into ammonia turbines. Also ammonia can be fired with coal or natural gas in existing setups. The main issue is neutralization of NOx exhaust.

Filter the exhaust through a caustic solution to neutralize NOxs.

While not in mass production, there is strong interest from the marine shipping industry. It can be produced near ports, and meets the storage and combustion engine constraints (similar to diesel) of the use case.

https://spectrum.ieee.org/why-the-shipping-industry-is-betti...

https://www.wartsila.com/media/news/30-06-2020-world-s-first...

https://www.lr.org/en/about-us/press-listing/press-release/i...

https://www.ammoniaenergy.org/articles/maritime-fuel-mix-cou...

A sibling comment mentions scrubbing NOx emissions as a significant issue, and it strikes me that the shipping/cruise industry is already a major polluter in that area. (Unlike cars, which must have catalytic converters because of local landlubber laws.)

High efficiency scrubbing appears to be feasible.

https://pubs.acs.org/doi/10.1021/acs.energyfuels.3c01419

I guess my point is that cleaner technology is already being avoided by those companies, because they can save a buck by polluting in international waters.

NOxs are practically zero with HCCI at a stoichiometric ratio.

There has been a lot of research in fuel cells that generate electricity from ammonia, with much simpler storage problems than for hydrogen.

Yes, fuel cells need more usage as we move away from oil & unnatural gas.

Direct propane fuel cells have some thermal issues, but recently there was a breakthrough in propane synthesis that would make it efficient to produce. Are ammonia fuelcells efficient?

I'm not sure I'd leap to "much simpler storage problems than for hydrogen" for a highly corrosive gas.

The lower explosive limit of hydrogen is ~4%. By comparison the 300 ppm immediate danger to life and health threshold of ammonia is .03%.

It is intrinsically dangerous, i.e. without a source of ignition, at concentrations 2 orders of magnitude lower than the LEL of hydrogen.

Not every hydrogen leak is a concern, but just about every ammonia leak is.

The established OSHA 15 minute exposure limit for ammonia is 35 ppm, 8 hours is 25 ppm.

But hydrogen likes to make invisible fires and leak through solid steel, and it needs to be ludicrously cold to liquify.

Generally speaking modern hydrogen pressure vessels are not metal for this reason, they are composite and not affected by embrittlement.

The Toyota Mirai, a production hydrogen car, uses a type IV carbon fiber pressure vessel rated for 70 MPa / 10,000 psi.

Type V are rated for 15,000 psi.

It is not necessary to liquefy hydrogen for adequate range in ground transport applications: The Mirai yields a 402 mile EPA rated range on gaseous hydrogen.

The tanks weigh 93kg filled with 5.65kg hydrogen, yielding an approximately 190 kWh of stored energy.

All without corroding flesh in trace concentrations.

By comparison the Tesla Roadster's 450kg battery pack yields a 200 kWh capacity.

Ammonia is and would likely continue to be stored in metal pressure vessels as an obvious cost optimization and thus would compare unfavorably to hydrogen pressure vessels' effective energy density where that area of the performance versus cost optimization space is not available due to embrittlement.

In Japan they're looking at adding Ammonia co-firing to coal plants:

https://about.bnef.com/blog/japans-ammonia-coal-co-firing-st...

I think many (most?) combined cycle plants use ammonia to destroy NOx in the exhaust (selective catalytic reduction). Some diesel cars use this technology as well (using urea instead of ammonia).

The strangest thing is that Japan is thinking about burning ammonia together with coal

https://about.bnef.com/blog/japans-ammonia-coal-co-firing-st...

which I just can't imagine being clean when I consider that nitrogen oxides are also a concern with combustion fuels, not to mention it being an inefficient "battery" if you're making ammonia from green hydrogen and then burning it and spinning a turbine.

Well, we don't necessarily need as much storage if we can just shift a good amount of demand.

Fertilizer production via this method might be a good fit for times when rates are low or even negative due to wind energy overproduction during off peak.

Farms have been producing their own fertilizer for centuries. ;-)

Millenia, even.

Yeah I know. Wasn't talking about that.

https://phys.org/news/2021-02-plasma-technology-world.html https://portal.nifa.usda.gov/web/crisprojectpages/1025777-lo... https://pubs.acs.org/doi/10.1021/acssuschemeng.2c06357 (paywalled)

"plasma" and "NOx" seem to be the keywords here (so other process than discussed here).

Not at scale (yet), cost unclear. But the technology exists, and being improved upon.

Yes, and yields were crap back then. Guano and then synthetic fertilizer changed everything.

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