[rini17]

I won't be surprised if this ends up solved in low-tech way - just mine and smelt 50 tons of iron/nickel and then build 1MWh Edison battery.

[Zhenya]

What's an Edison battery? I searched and did not find anything conclusive.

[rini17]

I meant this one: https://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery

[adamcharnock]

I think this is referring to a nickel-iron battery, or NiFe for short. It's old tech, but is pretty indestructible. I have 20 of them in my off-grid system.