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Comment by unchocked | Hacker News Reader

I find it odd that the author dismisses hydrogen storage largely based on the requirement to mine water for electrolysis and then goes on to propose using ~12,000 tonnes of water for thermal energy storage.

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12 000 t of water is a large swimming pool (about 5 Olympic pools) and could be used as such, perhaps.

Edit: using hydrogen for steelmaking or other reductive processes yes; for energy storage, we have better choices. You'd make it as you need it.

Storing water does not require pressure vessels, nor cryogenic coolers.

It pretty definitely requires pressure vessels if you care about it's phase.

Well it requires a closed container that maybe has to take a few psi of water pressure. It doesn't require anything that can tolerate thousands of psi like hydrogen does.

Oh for sure the storage problem is much much more difficult to solve wrt hydrogen than water, I was just being pedantic.

You can store hydrogen in lower pressures if you don’t care about the amount of space it takes.

That's a brilliant idea. You could store the hydrogen in some big balloons. There's no buoyancy on the Moon, so you don't need to anchor these balloons. You need to cover them with a dome to protect them from micrometeorites, but when you establish a Moon colony, building domes is the name of the game. At normal (on Earth) room temperature and pressure, a balloon with a radius of 10m holds about 60 kg of hydrogen. I did some back of the envelope calculations, and that would be enough to provide about 2 kW of power for the length of the lunar night (14 days).

More importantly, water does not diffuse through metal vessels.

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