The thinking in this article also explains the logic behind the solid metal fuel -- like iron powder for example. Basically oxygen reacting with iron (rust form

The thinking in this article also explains the logic behind the solid metal fuel -- like iron powder for example. Basically oxygen reacting with iron (rust formation) results in heat generation. One important detail around use of hydrocarbons for fuel to power things like cars is that you need the energy to be delivered in a timely manner -- typically within milliseconds of the spark. Whereas something like a power plant could be happy to have just a hot pile of iron metal powder giving off heat for weeks at a time rather than in one massive flash explosion. Using something like iron powder that is in a pure Fe unoxidized state would require some process to get the iron into that state. Likely requiring energy -- so probably the cycle for iron powder power plants would be to use solar/hydro/wind power to generate the power liberate the oxygen from the FeO2 molecule, then transport the iron to the place where it would be used that has poor access to solar/hydro/wind, then use that there. Anyway, articles like this really do a great job of making people think about things..