[Meandering]

This is interesting... I hope they can make it feasible in the long run. There is another interesting application for this oxidation phenomenon.[1] They burn iron dust to create a C02-free furnace. Imagine replacing coal with iron in concrete plants...

[1] https://newatlas.com/energy/bavarian-brewery-carbon-free-ren...

[teruakohatu]

Iron ore reserves: 168.6 billion tonnes Coal reserves: 1055 billion tonnes.

Coal energy density: 6.7 kWh/kg [2] Iron Ore energy density: 1.4 kWh/kg [1]

Total iron ore energy reserves: ~236.04 billion kWh [3] Total coal energy reserves: ~ 7,068 billion kWh [4]

So as far as energy goes we have 30x as much coal energy.

Now the rust can be renewed with energy ... but you need the energy to renew it in the first place.

[1] https://spectrum.ieee.org/energywise/energy/renewables/iron-... [2] https://en.wikipedia.org/wiki/Coal [3] https://www.nrcan.gc.ca/our-natural-resources/minerals-minin... [4] https://energyeducation.ca/encyclopedia/Coal_reserve

[jazzyjackson]

That's current proven reserves, not theoretical reserves, no? Because as we've seen with oil, the higher the price goes, the more we seem to find.

> but you need the energy to renew it in the first place.

So am I hearing you could create the iron-fuel someplace with excess energy and then ship this stored energy someplace that wants to burn it?

And while Iron loses out to energy density per kilogram, it wins on kilogram per cubic centimeter :D (your math is much appreciated btw)

[CorrectHorseBat]

Iron ore is mostly oxides so it was never going to be an energy source like coal, but an energy storage medium.

[yissp]

Is iron abundant enough for this to scale? Maybe this could kickstart the asteroid mining industry.

[ummonk]

The earth is made out of iron. There is no point in mining it in space, and regardless anything mines in space would be far too expensive for a use like this, which is why the main prospects for asteroid mining are precious metals.

[incompatible]

Yes, iron ore is mined in massive quantities in Western Australia at a cost in the order of $100 per ton.

[sbennettmcleish]

Yes, we're not gonna run out. WA ships nearly a billion tons/yr.

[Meandering]

You would use a fixed amount of iron and recycle it. It's not like you need "fresh" iron for every use.

[montecarl]

Iron is the 4th most abundant element in Earth's crust. There are almost 3000 times more iron atoms than lithium atoms.