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Comment by Filligree | Hacker News Reader

More efficient, but also more expensive and harder to scale.

To expand battery capacity you need to dig up lithium and half a dozen other rare elements, deal with the toxic byproducts (or dump them in a lake), manufacture batteries, control circuits and run ongoing maintenance.

To expand hydrogen capacity, you need more pressure vessels. These can be made of steel or aluminum, two of the cheapest materials in existence, and with practically zero pollution. Ongoing maintenance amounts to checking for rust and occasionally replacing valves, so it scales far better.

Hydrogen has serious downsides, but there's definitely a case to be made.

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Lithium's not just a little bit more efficient, it's like 2x more efficient.

I think converting H2 to methane and storing that is far more realistic than storing H2. Methane slots into all of our current natural gas infrastructure. Liquid natural gas cars are more practical than H2 cars.

However, we're going to be harvesting TWh-worth of lithium for our car batteries anyway, so we're going to have a huuuuuge secondary market of used car batteries that still have a consistent 50%-80% charge capacity that could be used for grid storage.

I think it's too early to see exactly how the technology will work out, but a huge lithium-ion economy seems inevitable. I truly hope that electricity -> H2 -> methane (or a carbon chain) happens though. Because that is carbon sequestration, and I think that in 2050 we're going to want to start paying people to do that and not let the result get emitted again.

> To expand hydrogen capacity, you need more pressure vessels.

Even simpler, you can store it in salt domes which are currently used for natural gas reserves. The pipes and related infrastructure may need to be replaced due to hydrogen embrittlement, but the storage itself is already there.

At the risk of sounding like an idiot, would there be any value in capturing some of the energy as compressed air/purified oxygen to be injected in to the hydrogen burning process... thingy? Perhaps in a manner similar to how a SABRE engine works? [0]

[0] https://en.wikipedia.org/wiki/SABRE_(rocket_engine)

Redox Flow Batteries can be expanded by also just adding more "pressure vessels" to store the charged electrolyte.

Which is why I'm more interested in Redox Flow than Lithium Ion, for grid-scale applications anyway. Lithium Ion's efficiency is necessary for cars or other mobile applications. But if you're building it on the ground, you just build a bunch of cheap heavy tanks all over the place.

I'd love some more info on Hydrogen storage, in theory and in real projects. If you have sources I'd much appreciate them.

Nah, what I already wrote already covers about everything I feel sure about, and half of it is just common sense. Shouldn't be too hard to find better sources, though.

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