Produces no *DIRECT* co2. The iron DID use coke in its production. Nice try, though..
They wouldn’t be manufacturing iron just to burn it, this is for scrap iron being recycled.
The idea these guys have is to use iron powder as an energy storage medium, that energy coming from renewables.
Direct reduction iron (sponge iron) doesn't use coke, nor does it melt the iron. The reducing agent is usually CO/H2 (town gas, syngas, coal gas, etc.) that's made from coal or natural gas. Sponge iron can be made with methane alone or just hydrogen. The H2 only method hasn't reached commercial status.
It's the hydrogen angle that brings in renewables. Yep, making hydrogen gas using solar (or nuclear). IDK if sponge iron is good enough for burning. Sponge iron can be made into mild steel (low carbon) in an electric arc furnace. That step will give off CO2 from any carbon in the iron.