There was an article on here the other day about a new approach to generating electricity from ammonia. The downside, though, is that creating ammonia needs H2 feedstock, which is often made by stripping the carbon off of methane obtained from natural gas.

If this is a useful way to get H2 feedstock for producing ammonia, that’s interesting on its own!

We used to make refrigerators using ammonia as the working gas, too, but concentrated ammonia kills.

    Exposure to high concentrations of ammonia in air causes immediate burning of the eyes, nose, throat and respiratory tract and can result in blindness, lung damage or death. Inhalation of lower concentrations can cause coughing, and nose and throat irritation.

Huffing gasoline is really bad, but not ammonia cloud bad.

Also the energy density of liquid ammonia is only about half that of liquid hydrocarbons. In the family of nitrogen fuels there's also hydrazine, which is much spiffier, but if you're worried about the toxicity of ammonia, well.. Yeah, maybe we don't want civilians filling up their cars with hydrazine.

The benefit of nitrogen fuels as a carbon-neutral fuel is that getting nitrogen from the atmosphere is a lot easier than extracting carbon dioxide from the atmosphere.