“Large” and “1 Megawatt” seems like a contradiction.

Interesting. Not necessarily practical, but unusual.

I had heard about iron flow batteries which also change the oxidation level of iron, but not about burning iron powder and reverting the rust to iron using hydrogen.

I think electrochemistry has better prospects in warm climates, where you most likely cannot sell the heat. Burning and converting heat into anything always has a penalty in terms of efficiency - but can get high power densities. In cold climates where reaction heat is a useful thing to consumers - maybe.

I wonder the energy cost of creating the powdered iron. And of converting iron oxide back to iron powder.

This is a cool concept. There are definitely possible issues that need to be hammered out, but I like seeing diverse ideas for energy production! Thanks for sharing!