[nine_k]

But this is perfect. A complete reversion of the reaction, without any additional interesting inputs or intermediate stages.

You can imagine a closed-cycle, isolated "battety" that discharges into sparkling water, and charges back into fuel and oxygen.

This is exactly the miracle solution that can turn CO₂ back into fuel, which can be burned again in existing ICEs and gas turbines, then turned into fuel again, powered by solar electricity.

Collecting and concentrating the CO₂ is going to be a task in itself, but things like power plants or steelmaking furnaces offer high-concentration, pre-heated CO₂.

[war-is-peace]

that would be cool, but wouldn't something simpler like electrolysis of water into hydrogen/oxygen work much better? I haven't the effort to do the math, but it would require less steps, less complexity, and less cutting edge catalysts with unknown lifetimes

[nine_k]

No.

It's hugely inefficient, so it requires more solar power.

Hydrogen is hard to store and use; unlike propane, it penetrates through plastics and even metals. Hydrogen is a good rocket fuel if you need top performance and cost is no object.

Propane is very convenient, and can be reused across the existing LNG infrastructure.

[mtrimpe]

Hydrogen is very difficult to use as a direct fuel source. This recent video gives a good overview of all the challenges a hydrogen engine has to overcome: https://youtu.be/DGL5g91KwLA

[war-is-peace]

thanks