[cyberax]

Ammonia can indeed be used as a longish term energy storage. It's not as great as methane (that can be pumped into underground caverns), but it liquefies at room temperature at just around 9 atmospheres or at -33C at atmospheric pressure.

Though it's pretty poisonous if it leaks.

[namibj]

It's corrosive to humans, toxic to aquatic life, but once you dilute it, humans survive easily.

The dangers are in confined spaces.

[kragen]

it's caustic if it leaks, but in the environment it quickly reacts to produce nontoxic products