Pure hydrogen has some handling difficulties which might be solved by binding it to carbon (eg in Methane: CH_4), or to nitrogen (eg in Ammonia: NH_3).

Ammonia production has as an advantage that nitrogen is available in large quantities in the earth's atmosphere (78%), and ammonia production and usage can therefore _theoretically_ be carbon-neutral (and in fact not involve carbon at all, ideally)

Methane production has as an advantage that you can produce it using atmospheric carbon capture (pulling CO_2 from the air), which means it could theoretically contribute to reduction of greenhouse gasses. A downside of atmospheric carbon capture is that earth atmosphere CO_2 is fairly low (0.04%) .

(note: Atmospheric CO_2 capture is also proposed for Mars ISRU (In-Situ resource utilization), which is one reason why SpaceX is using methane engines for its upcoming generation of (mars) rockets. There's some synergies / extra investments to be had in working on CO2 capture technologies)

(note 2: Current modern methane and ammonia production/delivery tend to use fossil hydrocarbons as the hydrogen donor, rather than water electrolysis https://en.wikipedia.org/wiki/Ammonia_production#Modern_ammo... )

Ammonia is injected into NG in gas turbines to scavenge N to stop NOx production: N is better at binding to N than to O. So, you just burn your NH3 slightly rich.

Ammonia is favored as the refrigerant in industrial cooling systems, but not domestic or automotive for safety reasons.

Ammonia may be burned in ordinary combined-cycle gas turbines and ship engines, requiring only new plumbing, because it corrodes some metals. The ship-building industry is already gearing up for the transition to ammonia fuel. Purely electrical synthesis production capacity will be low through 2026, because factories for synthesizers are still under construction.