There's no way people are going to be burning ammonia in personal engines. The pollutants from burning it are far worse than burning hydrocarbons. On industrial

There's no way people are going to be burning ammonia in personal engines. The pollutants from burning it are far worse than burning hydrocarbons. On industrial scales it might be feasible to scrub the exhaust (and even recycle them, since they're economically valuable) but on small scales I doubt it could be done.