this post was submitted on 04 Sep 2023
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Again? Did we stop?
It doesn't look like anyone has mentioned metallurgical coal yet. Even if you don't burn it for energy, the carbon in steel has to come from somewhere and that's usually coke, which is coal that has been further pyrolised into a fairly pure carbon producing a byproduct of coal tar.
Metallurgical coal only makes up for rather small part of coal mining, around 7% of all coal production goes towards it, and while the process produces more GHG than just burning it for power it has a less profound impact because it's just smaller. It's also one of the places where we can't really find an alternative, to produce steel you need to use bitumen coal because they have more carbon and less volatiles than charcoal.
On top of that steel is extremely recyclable meaning that any steel produced can be reused pretty much 1:1 with only a small amount of energy needed.
You can make really pure charcoal if you use plant fiber, like waste coconut husks. I guess it's just a cost issue?
More than likely it's a cost issue, coal is artificially cheap thanks to several countries subsidizing the coal industry like Germany, USA and Australia.
There's also I guess the practical question of how much plant fiber per ton of metallurgical coal is needed, i.e. how land would be dedicated towards 'producing plant fiber' for the steel industry.
Coconut husks are free with the coconuts, which is why I mentioned them. Without explicitly breaking out my highschool chemistry, I'm guessing you get about a third the mass of carbon from cellulose.
If it's a whole 7% of the coal mined, though, that is a pretty significant amount. I assume we'll have to find less agricultural ways of fixing CO2 at some point, because it is kind of a shame to use prime agricultural land to make industrial feedstock. NASA already has a device that can turn it into CO electrically, I guess.
How much of that carbon is emitted Vs embedded in the steel matrix? 50%?
I'm not actually sure. I imagine it depends on how exactly it's mixed in.
The green alternative would be to go back to charcoal (or "biochar" if you want to sound fancy), but it might be a bit more expensive.
So that's where the name coke comes from! TIL!
Coal is just Cola with the letters swapped around.