@badradger
And with catalyst action can be turned back to iron.
Kind of like hydrogen comes from water and the exhaust turns back into water.
@badradger saidHow much eneryg do you use to reduce iron oxide into iron and how much can you win back?
burning fine ground iron provides clean renuable energy.
This is more of an Engineering Problem of course
@Ponderable
https://newatlas.com/energy/bavarian-brewery-carbon-free-renewable-iron-fuel/
This piece says they would use solar energy to turn the rust back into iron.
Don't know the energy requirement for that but it would be renewable energy.