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Iron-to-rust cycle tapped by scientists for safe renewable energy transport
(interestingengineering.com)
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this post was submitted on 10 Jul 2026
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Source for claim of 1% mass loss per cycle:
https://research.tue.nl/en/publications/combustion-of-micron-sized-iron-particles-in-a-drop-tube-reactor/
I think the deciding factor between iron and aluminum comes down to exhaust filtration.
Iron oxide in the exhaust can be collected cheaply with a combination of centrifugal and electrostatic forces and it tends to retain is grain size. Aluminum oxide is lighter, more electrically resistive, and tends to break down into too-small nanoparticles.
Yeah, you'd only need to sinter pellets to pump hydrogen through them in a static pile. A fluidized bed reactor can reduce the iron oxide powder as is, and keeping the temperature lower prevents sticky sintering at the cost of taking longer to complete.
That source only covers losses due to iron evaporation during combustion, it doesn't cover reduction losses back into iron or what the regenerated iron's particle size is, which tells us what milling energy is needed to get back down to sub micron iron. That's the inefficient part of the energy loop, along with reduction efficiency with green hydrogen.
You need to understand that whatever method is being used for reducing your powder back into iron metal is going to be a mature technology already used for steelmaking. If green energy scientists somehow found a new method for reducing iron into metal it would be global breaking news in the steelmaking industry. That's the extraordinary claim you need to support with sources: how it gets regenerated and at what efficiency, does it need to be milled and to what starting and finishing particle size, consuming what energy, CAPEX, and OPEX? What's the total loop efficiency?
I really think the overall efficiency is going to be terribly low once you do the math on all steps in the cycle...