They mention that with hydrogen. It's cheaper to produce hydrogen but much harder to transport it. Fortunately, hydrogen can reduce iron oxide, which turns out

They mention that with hydrogen. It's cheaper to produce hydrogen but much harder to transport it. Fortunately, hydrogen can reduce iron oxide, which turns out to be a great complement. Their analysis is that the system cost of burning iron and renewing it at electrolysis plants is lower cost (and safer) than using hydrogen directly.