Embracing Our Interdependence With Nature
Permaculturist John Rogers in Melbourne Florida
I love the idea of making biochar on a small scale for my farm, but I am concerned about the SynGas release into the environment. I have heard that the methane released from this process is more damaging then if the carbon was burned into the atmosphere and not sequestered into biochar as done here. i have seen the youtube video and was wondering if there was a way to capture the gases emitted (if methane) and use this for other purposes).
Thanks for your comment Brian. I have had similar concerns. When I made that inquiry during a biochar presentation I learned that though some gasses are released into the atmosphere when the wood is charred, not as much is released as when the wood is fully burned to ash, and in the form of char the wood doesn’t break down or release its carbon the way it would if it rotted. From what I have read when biochar is added to soil it helps to sequester methane and other soil gasses. It is likely that if weighed the pros would far outweigh the cons of this issue. I am going to continue to study bio char and specifically this issue that you bring up.
The methane (and CO and hydrogen) produced by the pyrolysis front burns in the secondary combustion chamber and flue above the charring wood chips (assuming adequate secondary air is introduced at that point). These syn-gasses are decomposed in the secondary combustion. And this top flame provides the chimney effect which draws in primary air through the bottom of the bottom barrel. A smokeless burn is an indication of this desired efficiency.
TLUD (Top Lit Up Draft) technology is almost magic.
Ah nice save John, thanks so much for explaining what happens to methane, carbon and hydrogen during pyrolysis. I hope Brian sees this comment stream. Perhaps it deserves its own article as a follow up.
I know this comment thread is old but I thought I’d address Brian Blum’s concerns about methane and syngas emission (just in case anyone else comes along and wonders)
Brian, in the TLUD that John is proposing, the syngas (methane and hydrogen) is burnt in the secondary combustion chamber. The methane turns into carbon monoxide and the hydrogen turns into steam. If the syngas was simply released without being burnt, it would have a more negative effect upon the environment as methane is a more powerful greenhouse gas than carbon dioxide or carbon monoxide. The good thing about the TLUD design is that the methane is turned into carbon monoxide, thus reducing its greenhouse effect.
Syngas can be captured and used for other purposes (cooking/heating) but that would require a different sort of biochar production than the TLUD mentioned here. It is more complex too.
Of course some might be wondering about the fact that carbon monoxide and carbon dioxide are released by the TLUD. This is true, however the NET effect of creating biochar (including this method) is carbon negative. Remember that the biomass in the barrel will turn completely into carbon dioxide one day simply through decomposition. Turning it into carbon monoxide gas and solid carbon via the TLUD ends up reducing the amount of carbon put into the atmosphere.
Thanks for your excellent comment One Salient Oversight, and for lighting up this old thread.
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