I think the point of this is one can use intermittently available renewable sources of power (wind, solar, tidal) to electrolyse the rust to produce the iron po

I think the point of this is one can use intermittently available renewable sources of power (wind, solar, tidal) to electrolyse the rust to produce the iron powder for on-demand burning. The rust produced by burning can then be re-electrolysed to make more pure iron powder.