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Comment by vimacs2 | Hacker News Reader

There isn't a paywall I can spot in the original link - perhaps it's a regional thing?

What you might be missing here is that the "only downside" should be emphasized far more. Hydrogen is a bloody nightmare to store long term. It's boiling point makes the -20 C involved with this technology look like an oven and you really do want to ideally store it as a liquid since the exceptionally low molecular weight means leakage is a constant problem save for some very advanced (and expensive at scale) carbon composites.

Graphene seems to be a potentially excellent storage medium but we are still a while off from being able to manufacture that at the amount that would make it economically usable for hydrogen storage at scale.

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One way to store hydrogen safely long term is metal hydrides. Hydrogen readily infuses certain metals, like lithium, like water infuses a sponge.

The problem is that the density us rather low. Enough to store tritium in a nuclear warhead, but possibly a bit bulky for home use. (Also, the hydride remains flammable.)

Titanium hydride storage has been tested for automotive use. They shot hydride tanks with a rifle, and the result was less impressive than shooting a gasoline tank.

Also, hydrogen rises quickly as it burns, instead of spreading out on the ground.

Hydrogen is readily stored as liquid anhydrous ammonia.

I’d rather cleanup a diesel spill than an ammonia one.

Do you have more details on this somewhere? Maybe a nice semi-technical writeup?

With a bit of DDGing I found something [0] from March by the chemical society. With respect to storage density, NH3 is better:

Ammonia has a higher energy density, at 12.7 MJ/L, than even liquid hydrogen, at 8.5 MJ/L. Liquid hydrogen has to be stored at cryogenic conditions of –253 °C, whereas ammonia can be stored at a much less energy-intensive –33 °C. And ammonia, though hazardous to handle, is much less flammable than hydrogen.

This doesn't even mention how elemental hydrogen weakens metals over time ("embrittlement"), which makes storage even more challenging. There are lots of other issues discussed at that link, and it's clear that NH3 will be more expensive than e.g. gasoline, at least until there is better solar power. Still, if hydrogen makes sense, ammonia makes sense.

[0] https://cen.acs.org/business/petrochemicals/ammonia-fuel-fut...

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