[aifooh7Keew6xoo]

I'm not sure I'd leap to "much simpler storage problems than for hydrogen" for a highly corrosive gas.

The lower explosive limit of hydrogen is ~4%. By comparison the 300 ppm immediate danger to life and health threshold of ammonia is .03%.

It is intrinsically dangerous, i.e. without a source of ignition, at concentrations 2 orders of magnitude lower than the LEL of hydrogen.

Not every hydrogen leak is a concern, but just about every ammonia leak is.

The established OSHA 15 minute exposure limit for ammonia is 35 ppm, 8 hours is 25 ppm.

[thfuran]

But hydrogen likes to make invisible fires and leak through solid steel, and it needs to be ludicrously cold to liquify.

[aifooh7Keew6xoo]

Generally speaking modern hydrogen pressure vessels are not metal for this reason, they are composite and not affected by embrittlement.

The Toyota Mirai, a production hydrogen car, uses a type IV carbon fiber pressure vessel rated for 70 MPa / 10,000 psi.

Type V are rated for 15,000 psi.

It is not necessary to liquefy hydrogen for adequate range in ground transport applications: The Mirai yields a 402 mile EPA rated range on gaseous hydrogen.

The tanks weigh 93kg filled with 5.65kg hydrogen, yielding an approximately 190 kWh of stored energy.

All without corroding flesh in trace concentrations.

By comparison the Tesla Roadster's 450kg battery pack yields a 200 kWh capacity.

Ammonia is and would likely continue to be stored in metal pressure vessels as an obvious cost optimization and thus would compare unfavorably to hydrogen pressure vessels' effective energy density where that area of the performance versus cost optimization space is not available due to embrittlement.