> So what happens to all that rust? This is where things get clever, because the iron isn’t just a fuel that’s consumed— it’s energy storage that can be recharg

> So what happens to all that rust? This is where things get clever, because the iron isn’t just a fuel that’s consumed— it’s energy storage that can be recharged. And to recharge it, you take all that Fe2O3, strip out the oxygen, and turn it back into Fe, ready to be burned again. It’s not easy to do this, but much of the energy and work that it takes to pry those Os away from the Fes get returned to you when you burn the Fe the next time. The idea is that you can use the same iron over and over again, discharging it and recharging it just like you would a battery.