Ammonia as a fuel for compression ignition engines

https://www.ammoniaenergy.org/articles/review-of-ammonia-as-a-ci-fuel-published/

by airstrike • 6 years ago

55 42 6 years ago

djrogers• 6 years ago

Soooo... It has to be mixed with a co-combustion fuel, is dirtier than diesel, and requires more space and weight to clean up it's exhaust.

The article really should have gone into some of the 'why' side of things - what are the advantages of ammonia?

piannucci• 6 years ago

Knowing nothing about this, broadly speaking, the enthalpy of formation of the diatomic nitrogen molecule is very high, and you might expect to achieve high energy density. Also it does not produce any CO2.

neltnerb5• 6 years ago

So for context -- I was working on this ten years ago. I don't have much to say about this particular example other than to note that almost all ammonia today is made using natural gas as the hydrogen source.

Using ammonia is a neat idea, if made renewably, but it will continue to be a challenge to use in cars because it is pressurized, corrosive, and toxic even compared to gasoline.

Obviously the bigger market for renewable ammonia should be fertilizers because right now we're feeding our crops petrochemicals in order to get high enough yields to feed us. That seems like a bad situation to put yourself in if there's any other choice.

jccooper• 6 years ago

If they had a FAQ I'd be looking for "How does ammonia power handle the many significant dangers of ammonia?" Except when extremely diluted that stuff makes diesel look like milk.

FranOntanaya• 6 years ago

Maybe it'd work for large trucks in very cold environments. Not much around in an accident and it handles lower temperatures.

asdfadsfgfdda• 6 years ago

The main "why" is a carbon-free fuel (when produced by solar) in a relatively dense form. Liquid ammonia has higher energy density than liquid hydrogen, is easier to store, and is already used a bulk chemical around the world. It also is more energy efficient than liquifying hydrogen.

If you imagined what oil would look like without carbon, ammonia is pretty close. The toxicity probably prevents cars and trucks from using ammonia, but for marine power or grid energy, it seems feasible.

Also, the co-combustion fuel can be supplied on-site by cracking the ammonia to hydrogen.

https://www.kallanishenergy.com/2020/07/08/air-products-to-b...

elcritch• 6 years ago

Cargo/freight shipping could be a prime target for a cleaner ammonia base fuel as most of the ships currently run dirty semi-processed petroleum, “bunker fuel”. It’s a hyper-cost sensitive market so without regulation I’d doubt ammonia would compete. Still it could be a feasible option to reduce pollution. Some Western countries might accept ammonia or similar diesel replacement, as it’d be a sort of natural tariff, but likely China would lobby hard against such a measure. There’s have to be a very strong push from a few nations, which I’ll doubt we’ll see anytime soon.

lpcam332• 6 years ago

What is the energy return of energy invested on getting hydrogen from solar and then turning into ammonia?

dTal2• 6 years ago

I'm confused. If we're stipulating carbon-neutral liquid fuel from renewable energy, what precisely is wrong with depolymerizing organic matter into ordinary hydrocarbons? Sure it generates CO2 at the point of use, but it's offset by the photosynthesis that made the organic matter. As long as the carbon cycle is a closed loop there shouldn't be problem, right?

rbanffy3• 6 years ago

Liquid ammonia has higher energy density than liquid hydrogen

Why not rockets then?

jessaustin• 6 years ago

It has to be mixed with diesel in order to function in compression ignition engines, otherwise known as "diesel engines". So, this "criticism" could be leveled at gasoline and other fuels as well. Spark plugs will ignite ammonia just fine. There is a single reference to this in a different post on the site. [0] My understanding is that most "hobbyist" ammonia fuel setups (i.e. "my pickup runs on ammonia now!") also use spark ignition. I suspect they're investigating the diesel engine possibilities because they would require fewer modifications to existing large marine engines.

[0] https://www.ammoniaenergy.org/articles/wartsila-tests-intern...

abe_m2• 6 years ago

I came across this a few years ago. The largest problem is that Ammonia is very toxic. It is also very corrosive. If you look around, there a lots of articles about problems when delivery systems are used to transport ammonia, and then propane. Trace contamination causes failure in propane systems due to corrosion.

So in a crash situation, if the ammonia ruptures, you're probably dead, and everyone else in the vicinity. With gasoline, diesel, propane, or natural gas, if the tank ruptures, people in the vicinity are likely fine if it doesn't ignite. On heavy trucks, ruptured diesel tanks are quite common in crashes. Fires lighting from them, much less common (i.e. most ruptures don't result in fire).

The article is devoid of any comment on the safety aspects, which from what I see, is likely the more important point.

VBprogrammer• 6 years ago

Typically the good thing with ammonia is that it's smell is easily detectable by people well below it's toxicity level. I don't think this helps if the tank us crushed and you are trapped inside an upside down car right next to it though.

I think for the most part it is more interesting as a energy storage from renewable overproduction than in cars.

rbanffy3• 6 years ago

Only if the energy storage facility is far from everything.

A large tank leak and you'll end up killing a whole city.

AprilArcus2• 6 years ago

This is a very reasonable point, and even somewhat understated, since even when ignited hydrocarbon fuel burns more safely than ammonia. Nitrogenous compounds don't ignite and gradually burn off; they detonate.

mannykannot• 6 years ago

Don't try this at home, but IIRC from my mis-spent youth you can light the ammonia gas in a half-empty bottle of household ammonia solution and it will burn off quietly.

According to Wikipedia (which suggests that my memory may be faulty in this case):

"The combustion of ammonia in air is very difficult in the absence of a catalyst (such as platinum gauze or warm chromium(III) oxide), due to the relatively low heat of combustion, a lower laminar burning velocity, high auto-ignition temperature, high heat of vaporization, and a narrow flammability range."

Unlike nitrate compounds such as ammonium nitrate, ammonia contains no oxygen, and disassociates into hydrogen and nitrogen only.

airstrike2• 6 years ago

So in a crash situation, if the ammonia ruptures, you're probably dead, and everyone else in the vicinity.

I think the assumption is these would be mostly used for stationary power generation / marine vessels, not on-highway vehicles.

jobu• 6 years ago

If you look around, there a lots of articles about problems when delivery systems are used to transport ammonia, and then propane.

That's most likely related to meth production. They steal anhydrous ammonia (usually from farmers) and try storing it in propane tanks which are not designed for that. The tanks corrode or crack and then leak or explode.

I've also heard of farmers crashing their tractors into ammonia tanks or train cars of ammonia derailing, but generally speaking, the storage and transportation of ammonia is a solved problem. It's been used for industrial purposes for around 100 years and for agriculture since the 1950s. Based on on what the article said about NOx pollution and aftertreatment systems it's unlikely it will ever be viable for autos or any personal use where safety or risks are more of a concern than they are currently.

abe_m2• 6 years ago

While I understand that can be a problem, I'm talking about in legitimate propane distribution infrastructure. An example is here: https://www.lpgasmagazine.com/ammonia-contamination-episodes...

From what I understand, the steel tanks are built to the same standards for both gasses, but ammonia is corrosive to copper alloy valves and fittings. Trucks can be built to haul both and don't use copper alloy fittings. Propane only systems (like home heating systems) contain copper alloy fittings, and the valves and fittings can fail.

CyanLite2• 6 years ago

Ammonia production consumes about 2% of the world's energy and generates 1% of its CO2.

Animats• 6 years ago

MAN, the biggest producer of marine diesels, was supposedly working on this. But there's nothing about it on the MAN site. Just on the "ammoniaenergy.org" site.

The case for marine diesels is reasonable. The energy density is higher than bunker fuel, and the fuel only has to be available at major ports.

ZeroGravitas2• 6 years ago

I belive Maersk has decided on Ammonia as the future for their ships, with refits of diesel engines acting as bridge to fuel cells.

airstrike2• 6 years ago

MAN and Wartsila are both working on it

Paywalled, unfortunately: https://m.shippingwatch.com/article/12359286

AngryData• 6 years ago

Scariest shit I ever did was help pull a completely full anhydrous ammonia tank out of a 6 foot ditch. The trailer it was attached to had slid off the gravel road and twisted upside down in the ditch, some nearby farmer bringing it home from fillup. And it was not made to be picked up at all when full, but you know smaller farmer not wanting to lose his ass and farm with it by calling out some hazmat crew to drain it and transfer it. Used an excavator with a chains to very carefully pick it up and roll it out onto the road so they could pull it onto another trailer. If that fucker cracked open basically all of us down in that little valley would have died horribly. But doing dangerous as fuck shit on the cheap is the only way these small time farmers are holding on in the face of corporate monoculture farms, and hope they can survive long enough for those corporate farms to leave the area when the soil is depleted and worthless from their unsustainable practices.

pfdietz• 6 years ago

One use case for ammonia is in alkaline fuel cells.

Ammonia can be reformed to nitrogen + hydrogen by passing it over a hot catalyst. The gas coming out is free of CO2, so it can be used in alkaline fuel cells without carbonate formation (the CO2 in the air used by the cell must still be scrubbed, but that's an easier problem).

Alkaline fuel cells can use nickel instead of platinum electrodes.

Ammonia as a fuel for compression ignition engines

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