There are a lot of papers advocating for a switch away from fossil fuels, and even H2 fuel cells, to ammonia based propulsion in transport. It can be used in combustion engines but there's a risk of NOx production. So the greenest option to me is ammonia to H2 conversion or direct ammonia fuel cells. It's got the same advantages of classic H2 fuel cells but without the constraints of cryogenic or pressurized containment of H2. And ammonia has a better energy density. But it's toxic for humans and, above all, marine life! Especially for fish species. So I'm feeling a bit uneasy about potential mass ammonia spills…
Large amount of any chemical pufiried, concentrated, and spilled in one place is a disaster
Improper utilization of any energy storage media - wood, electricity, even gyro-storage - is dangerous and produces hazardous waste
It's all about being technological and playing fair. There is nothing that switch from one energy storage to another would accomplish in terms of environmental safety.
I love NH3 idea, it's IMO 3rd best solution. Second best is alcohol. First best is making your energy locally with whatever you have and not wasting it for stupid things.
But all this will be easily messed up by reckless greedy maniacs that have most of the power in the world right now.
Here is something my dear friend wrote I just read yesterday: https://alexshvartsman.com/2024/12/03/the-rattler-by-leonid-kaganov/