> but is iron optimal for such an approach? I found the question equally intriguing. This is still an energy storage medium, so think of it like a very energy

> but is iron optimal for such an approach? I found the question equally intriguing. This is still an energy storage medium, so think of it like a very energy dense battery rather than a true fuel & today it is produced by burning carbon in coal/coke. That aside, for a solid powder fuel, pretty much yes. That 2nd article lists out why it is most likely the best choice, but to collect everything I read together. 2nd most abundant (Al is more), powder burns into powder oxide which can be separated easily (not corundum glass), production capacity exists across the world (not exotic material), the waste product will dissolve in acidic water (for cleaning), but isn't a "heavy heavy" metal (we can excrete iron through our kidneys), decent flame capacity (magnesium would burn hotter, maybe), very shelf stable, degrades into the final product (it rusts, but then you dump it the same way), won't catch fire by itself (not like the alkali metals or sulfur/phosphorus) Eventually, there's just a few non-carbon elements which even hit a part of those - Al, Si and Fe. And the other two make it one-use only with glassy (literally) oxides.