What are the byproducts of coal pyrolysis?

Good morning Permies!

It occurred to me to wonder what would happen if you did a retort-style pyrolysis using coal. Would the char left behind be at all akin to the char produced from fresh and dried biomass?

I then found this article that deals with the subject.

Does anyone have information on this? I mean, I know the underlying issue would still be the mined carbon being released to the atmosphere, but at least if coal was useable in a pyrolysis process that produced char that could be composted to be sequestered in the soil, less carbon would be released than through gasification or straight combustion. And all the volatiles would be cooked off and burned as fuel for the process, and for whatever process all that heat would be used for.

Am I missing something?

-CK

Chris Kott wrote:... at least if coal was useable in a pyrolysis process that produced char that could be composted to be sequestered in the soil, less carbon would be released than through gasification or straight combustion.

I see the title to the thread is asking about coal pyrolysis byproducts, but it seems to me it would just be best to leave the carbon (coal) in the ground in the first place instead of mining it to make char to compost in order to sequester that carbon, since it was already sequestered prior to mining.

Well of course, but in places where it is getting burned regardless because it makes the most economic sense, like for instance you literally have a vein on your property, or a poor municipality has easy access to the cheap resource, it would be good if there were a better way, and one that fulfilled a permacultural function.

There are places in this world where their transition in an energy crisis would result in a brown energy future as described in David Holmgren's Future Scenarios due to economic issues and supply constraints. Some places will have the resources necessary to transition to a solar thermal mirror array system for their industrial production, while others will be stuck with old infrastructure, trying to make the best of what they have so the power stays on and the mains keep pumping water. My thought was that if there was a cheap way to use some of the energy in coal and sequester the most of it in soil as biochar, there could at least be some silver lining to that carbon cloud.

This only works, though, if the end-product is actually just a similar carbon product to the activated charcoal we use to make biochar. Which leads me back to my question.

-CK

Chris Kott wrote:Good morning Permies!

It occurred to me to wonder what would happen if you did a retort-style pyrolysis using coal. Would the char left behind be at all akin to the char produced from fresh and dried biomass?

I then found this article that deals with the subject.

Does anyone have information on this? I mean, I know the underlying issue would still be the mined carbon being released to the atmosphere, but at least if coal was useable in a pyrolysis process that produced char that could be composted to be sequestered in the soil, less carbon would be released than through gasification or straight combustion. And all the volatiles would be cooked off and burned as fuel for the process, and for whatever process all that heat would be used for.

Am I missing something?

-CK

Boy oh boy... Where angels fear to tread
Well If you burn off the pyrolysis gases from coal you will still be releasing significant CO2 into the atmosphere. PLus whatever trace elements are in the coal will end up in the air or the resulting char; lead and mercury come to mind. Removing pyrolysis gases from coal is really what making coke is for steel making. Having lived in Hamilton Ontario and seen those plumes of orange, green and brown flames and the smells that go with it I can tell you I would want no part of it. Clean coal is a political creation. Maybe not as evil but still evil...

That's all a part of coal gasification. I am wondering about a proper high-temperature pyrolysis, wherein all the volatiles are combusted, and at such a high temperature that nothing escapes but CO2, and maybe some CO and water vapour, and that most of the carbon in the process would be left as a porous solid carbon matrix.

Again, coal is going to be used somewhere, and likely for a long time, and probably not in high-tech, highly efficient processes. So I was wondering if there's anything that could be done to ameliorate this situation.

Travis mentioned in a few posts that when it gets really cold on his homestead, he has the option of switching to coal, which will get his home something like 10 degrees warmer in the coldest winters, if I am remembering correctly. Now if this remained true, but a home pyrolysis appliance, perhaps a purpose-built RMH with a retort insert, were used for a cleaner combustion and a char byproduct, assuming the char was devoid of pollutants or toxic elements due to the nature of the pyrolysis, would that not be better than a lower-temperature, more polluting complete burn?

This isn't a suggestion that we dig up all the coal and pyrolyse it for energy and to make soil. That would be dumb. That would literally be mining carbon, using energy to derive energy from something we want to put back in the ground. That wouldn't make environmental or economic sense.

-CK

Better in this case is not good... If someone is destitute but they have coal they will burn it... would they stop at char when 3/4 of the energy is left? Probably not...