this post was submitted on 31 Oct 2023
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Carbon Dioxide Removal (CDR)
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CDR is removal of CO2 from the atmosphere - an essential basket of technologies for achieving UN IPCC best outcomes to mitigate climate change. This is a community for discussing advances and issues of CDR.
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I made an electric biochar reactor to test the idea of capturing the syngas! What a magnificent smoke factory! https://www.openairforum.org/t/experiment-4-electric-fired-biochar-reactor-d/838/1 -- I did collect a bit of pyrolysis oil but my primitive gas collection system was no match for the smoke particles and the garage will probably never be the same. They say pyrolysis oil production is favored by "fast" pyrolysis and at first I did not know what that meant - 30 minutes seemed relatively fast to me. But it turns out that fast means several SECONDS. To do that you need biomass cut into small pieces and heated very quickly. A way to do that is with molten salt but for some reason, my wife has forbidden this class of experiments in our garage for now . . .
Phenomenal work, very impressed! I'm kind of shocked at the idea of reliably performing pyrolysis in seconds, that sounds like it would require the energy of a massive fresnel lens and be quite dangerous. I do extensive solar cooking from late spring to fall but am pretty leery of using serious focused energy.
Anyway, very cool. What did you do with the resulting pyrolysis oil? I know little about it beyond its capacity for heat generation through combustion.
I think the most likely route to fast pyrolysis will be as an adjunct to power generation with solar power towers in the midst of heliostat mirrors - just speculation.
I only made a small amount of pyrolysis oil - not enough for any further experiments. I recently have read that it can contain quite an array of fairly toxic benzene-family compounds. It could be refined and "cracked" to make a range of products now made with petroleum, but I just washed mine down the drain into my septic tank (where it will probably remain for some centuries).
That wouldn't surprise me. Probably the best thing we can do for the time being is to immediately combust it for heat. The heat could be used to maintain a constant pyrolysis process, adding in more feedstock basically forever, or to heat buildings. That would be one way to bootstrap a biochar industry so that further research can determine ways to make syngas into a commercial product.
I've also been wondering about using biochar creation with syngas combustion for water desalination or just plain running a steam turbine. Seems like there's a lot of potential.