Over at a politics board I belong to there are several cats who are beating the drum about an “ammonia economy.” The idea is that, with some modifications, you can convince an internal combustion engine to run on ammonia. While I don’t think they’re pushing for ammonia cars at present, they seem to think that agricultural machinery would be a good place to start, on the theory that the people who use it are already used to dealing with the ammonia, or ammonium compounds, that this plan requires.
Obviously, you can tell I know next to nothing about the science involved. Would this work, or is it another car-that-runs-on-water?
I know very little about the science involved, but it’s at least not a spectacularly stupid idea on it’s face, since the combustion products of Ammonia in Oxygen are just water and Nitrogen. Nitrogen is already 70+% of the atmosphere.
I wonder, though, if incomplete combustion would product NO[sub]x[/sub], which are famous for lending their brownish color to smog.
Where do they propose we get the ammonia? It’s not naturally-occurring in anywhere near the abundance of carbon-based fuels, which means we’d need to make it, which means we’d need to supply energy. And where does that energy come from?
It’s all the same problems as hydrogen fuel, except with the added bonus of being poisonous.
It talks about the company HEC making all kinds of generators and other engines for different kinds of fuel, so it would seem that it is a regular internal combustion engine, but it does not say explicitly.
I found another discussion site that had people debating it and there was mention of fuel cells. Hmm – need to look into this more when I get home…
Ammonia is NH3, so it’s in some ways a hydrogen carrier. There’s a group called the Ammonia Fuel Network (AFN) that’s pushing this concept - they’ve got a website, so they must be legit!
Direct combustion of NH3 would result in quite a bit of NOx emissions, although there are ways to minimize that. The thing the AFN is promoting is that NH3 combustion does not rely on the carbon cycle - except for the fact that nearly all ammonia is now made from natural gas.
I don’t know who’s behind all the ammonia fuss, but it does have some technical viability, even if it’s probably not practical.
I personally think the methanol economy (Olah is a big proponent of this, with a monograph and an Angewandte Chemie Int. Ed. publication on the subject) would be a more obvious choice. Of course, both compounds have problems. Methanol reacts with Al, Zn, and Mn. Ammonia reacts with Cu, Zn, and various rubbers and liquid ammonia dissolves a lot of metals. Both have toxicity issues and of course we still have to produce the stuff, no matter what we use.
We obviously make the ammonia using the Haber-Bosch process, but that just means we need a source of H2. On the plus side, the reaction is exothermic. However, we’re kinda stuck with that process. With methanol, we have more options.
One the one hand, ammonia will liquify at ordinary temperatures under pressure, so it’s storable. On the other hand ammonia is one of those things that when a railroad tanker car of it spills, they evacuate everyone for miles downwind. CFCs were invented to replace toxic flammable ammonia in refrigeration systems. I would not want to be immediately downwind of even the ten gallons of liquid ammonia that could be spilled in an auto accident. My verdict? Too impractical.
Ammonia is commercially produced through the Haber Bosch Process. It is incredibly energy intensive and given the 92.4 KJ/mole needed even with a perfect catalyst, will allways be very energy intensive. Once we get this whole free energy thing figured out, I think this is a great plan.
I would worry about the hazardous nature of ammonia, meth heads and the potential nitrate polution but once we have free energy I’m sure we will have instant disaster control, access to the phantom zone and flawless polution control.