Ammonia, page-8

Yes I've read that nitrous oxides (NOx) are produced from burning Ammonia such as when used as a fuel for internal combustion enginesor turbines. Nitrous Oxides are a GHG, the precursor to smog, and generally bad for human health.

And cheating on NOx emissions is what VW dieselgate was all about.

https://www.newscientist.com/articl...ot-so-harmless-and-could-damage-human-health/

https://www.sciencedaily.com/releases/2017/05/170523081855.htm

Yes you're quite correct that the efficiency and energy consumption of the ammonia decomposition process will be critical to the vability of ammonia as a hydrogen transport. The reverse process (Haber-Bosch: nitrogen + hydrogen ==> ammonia) is already pretty energy intensive but has advantages for bulk transport since cooling and liquifying hydrogen for transport is also very energy intensive.