> Rather, it's using the energy to deoxidize rust. Exactly, really what they are storing is electrons. Rusting the iron directly releases heat, which limits y

> Rather, it's using the energy to deoxidize rust. Exactly, really what they are storing is electrons. Rusting the iron directly releases heat, which limits your efficiency to the delta-T of the process. Reducing steam to hydrogen and then converting the hydrogen in a fuel cell allows higher efficiency to produce electricity.