[ianburrell]

You don’t have to keep it cool. Ammonia has similar profile to propane. It is liquid at 7-14 bar. We build pressure tanks like that all the time for propane.

Ammonia is probably too unsafe for cars and boats. But anything filled by professionals like trains or ships would work. But might work to have tank exchange system like with propane.

[LorenPechtel]

I was thinking about that but it's only a liquid at those pressures if you can keep it from getting too hot--say, a tank sitting there under the desert sun. And if your pressure relief triggers on ammonia it's a lot more of an issue than if it happens with propane.