They’re using hydrogen to de-rust iron, and later let the iron rust again. I don’t have a degree in chemistry, but that sounds like a scam.
There are basically two sources of hydrogen that matter at an industrial scale: fossil fuel cracking (not clean energy) and electrolysing water. In the first case, if you want power it’s more green to burn the fossil fuel directly.
And if you’re electrolysing water and then using the hydrogen to chemically derust iron, it would (as far as i understand with high school chemistry) be strictly more efficient to electrolyse rust directly. The oxygen can dissipate into the environment or be reintroduced as necessary, like with a sacrificial metal for ship’s hulls.
It’s undoubtedly innovative that they have a relatively efficient way to store the latent chemical energy of hydrogen given an excess of hydrogen, but in terms of energy storage that is putting the cart before the horse.
it would (as far as i understand with high school chemistry) be strictly more efficient to electrolyse rust directly
I’m not a chemist either, but I do know a bit of chemistry.
Typically, you need a solution of NaOH (sodium hydroxide) to directly reduce iron oxide in an electrolysis cell. If your iron oxide contains impurities, those may react with NaOH and ruin the fun. Also, if you have exposure to CO2, your NaOH will gradually degrade, producing NaHCO3 and losing potency.
My impression: wet electrolysis is great for making high purity iron, but it would be hard to make it work for energy storage.
