Off gas problem from making biochar

This was a question that I didn't have a really good answer for, so I will serve it up to the community.  I figured that most of the off gases were part of nature, and stabilizing the carbon is the benefit.    Anyone know about wood gasifiers?



"I'm wondering about the offgas from making charcoal, it appears to contain some tars and other ickies that I don't necessarily want to release into the atmosphere, and I wonder if the most ethical way to make charcoal is in a wood gassifier while sumultaneously using the gas produced for some homestead task like heating water or something. Is this something that has been discussed? Thank you!"




Thanks,
John S
PDX OR

I can't speak to toxicity, but the "closed-in fire" smell of the off-gases will test the goodwill of your neighbours. It stinks like the devil. At least that's what my small-scale kiln experiments have shown.

I have seen (but not tried) two kiln designs that address this. The commercial designs pipe the off-gases back into the burn chamber, keeping the heat up as the char finishes. The second method, which I would like to try, uses a smaller barrel full of wood for char, inverted and set on blocks inside a larger barrel, which provides the burn chamber for wood initially and then char gases later in the cycle.

Personally, I use a continuous-burn-and-tamp method in a half barrel or pit. A tight-sealing lid goes on when I'm finished. It seems to work okay (though purists may roll their eyes). Someday I might get fancier.

What Douglas said.
However you do it,  and even if you don't capture the heat for use,  always burn those off gasses.

From what I have seen a TLUD stove is the simplest way to make char and make use of the heat produced.
I have struggled to use them without highly processed fuelstock ,  but others seem to have little or no problem.

TLUD's have been used to heat homes, power stove tops and fire ovens.
These functions are not always needed.
When that's the case,  drying fuelstock , baking clay bricks or distilling water are functions that produce a storable yield.

William Bronson wrote:What Douglas said.
However you do it,  and even if you don't capture the heat for use,  always burn those off gasses.

From what I have seen a TLUD stove is the simplest way to make char and make use of the heat produced.
I have struggled to use them without highly processed fuelstock ,  but others seem to have little or no problem.

TLUD's have been used to heat homes, power stove tops and fire ovens.
These functions are not always needed.
When that's the case,  drying fuelstock , baking clay bricks or distilling water are functions that produce a storable yield.

Hello everyone.

I am curious how one would go about building a unit to produce biochar from wood sources.  I will be setting up orchards with alley cropping using Inga edulis & like species (In Colombia), & would like to continue to improve the soil using biochar with the branches pruned.  I also use charcoal in my aquaponics system which will be feeding the alley cropping as well, so this would be an added utility for the biochar.

This one works for me.  The big difference is when you make the chimney, just measure your chimney, draw the circle, and use that as your guide.  Also, drench the coals when the flames just barely go above the coals.