Like any fuel, ammonia has emissions. Super interesting piece on the difference between doing ammonia properly vs. getting it wrong that goes into a lot of detail on emissions:

How much energy is used to produce ammonia fuel? The method of presenting the information here is very annoying and a waste of time.

My friend used to work on ammonia referigeration in food storage, and supermarkets. He used to joke that if there was a leak you could find it easily by just looking for the dead customers.

I used to work in an ice cream factory and the refrigerant used was ammonia, The refrigerant lines were painted a bright yellow and railing was use to protect exposed lines.

Yes I love the smell of nitric acid in the morning. The various nitrogen oxides also give an irreplaceable orange glow to the air.

Rotten eggs is Hydrogen Sulfide, totally different chemistry

I was surprised that a chemist would not know the smell / attack of ammonia. I used to smell it around pet owner's homes. I was even once given smelling salts in my middle school.

i remember the coast guard giving out warning over the radio whenever a tug pulling an anhydrous ammonia barge would come into the bay... 1000 foot clearance for any other traffic... look up ammonia plant explosions on the web

Roads lined with dead flies, including bees. Used to work at a firm that used liquid latex. It gave off ammonia when the top was off. It soon acquired lots of black spots on the surface as insects flew too close and died. Sure wouldn't want to pump the stuff or work on the engine.

Ammonia-powered cars make absolutely zero sense when ammonia's extreme causticity is a core reason why we aren't using it as a domestic refrigerant in fridges, freezers and heat pumps despite being one of the best options otherwise.

Doesn't the Haber-Bosh process generate CO2? It seems to me that any carbon reduction from using ammonia fuel would be offset by the increased CO2 generated in making that ammonia.

Lovely, we're abandoning diesel because of NOx to replace it with this?

What do you mean, "back to burning liquid fuels?" Roughly 99% of us never left.

I was a cargo engineer on gas tankers. Occasionally we carried ammonia. When we did you always had strapped to you a mini BA set. Ammonia loves moisture, so the eyes nose and mouth get it first.

That was nothing, I've been hit by refrigerant grade ammonia and trust me you never ever want to go there, for a while I did not think I was going to survive it. Super dangerous stuff! I left a really big mess on the floor from what came out of me. I was not actually in the cloud I was just close. Gives me chills thinking about it.

Drag racers tried something similar a long time ago. They used Hydrazine. Led to engine blow ups and eventually being banned. Ammonia has to be transported in very heavy steel cylinders which are used as is to refill refrigeration systems. To use it in cars would need a lot more than just a squirty hose gun to get it transferred.

Instead burn ammonia directly in a combustion engine, some companies are developing ammonia truck with a electric motor. Yes. The ammonia molecules (NH3) are broken in N (nitrogen) and H3 (hydrogen) in a special device and hydrogen go a fuel cell that converts it in electricity that feed a electric motor. This is much more efficient, because the efficiency of the electric motors are much more higher (> 95%) than a combustion engine (> 35%).

I helped my dad put a propane retrofit kit into a 1995 Ford F350 in 1996, It was super easy then and has become way more efficient since. It requires less modification than one would assume to make an engine run, it has an existing safe infrastructure and is readily available in the U.S.A, but nobody ever considers it as an option. Why?

The nice thing about petrol is that it's safe enough for use by the general public -- even those idiots who smoke cigarettes while filling up are usually OK.

NH3 is interesting, but the biggest problem is that it is NOT a fuel. You don't just drill holes and out comes ammonia (but that does happen with oil). You need to put energy into first obtaining H2, (which typically comes from natural gas turning into CO2 and H2 - another CO2 producing industry) or from electricity (which would be best if nuclear, but most are driven also by fossil since they have to run 24/7) and THEN you have to take the H2, mix it with N2 (which came from the energy to make liquid air and fractionally distill it), run it at high pressure and about 700 C and you get NH3. More energy is used to compress and store it. NH3 production consumes 2% (!) of the world's energy now. It is basically a liquid fuel battery, NOT a source of energy or "fuel". The Hydrogen revolution has a similar problem and has even worse problems for storage, energy density, etc. Interestingly HTGR and MSR (Gen IV reactors) run at high temps and could be used as direct heat sources for making NH3 (which would save that 2% I mentioned earlier, and more if it did get used as a liquid fuel). However, if you really want liquid fuel as energy storage, consider what the military does - use nuclear heat to make carbon-containing fuels (yes, they have carbon, but now you've closed the cycle). Lastly, any time you burn almost anything in an engine (including NH3) you will make some NOx emissions. Electric cars (and fuel cells) don't burn things to produce energy (in of themselves) so they don't produce CO2 and NOx (nor HC).