Dakota fire holes are easy to build/dig, burn cleanly and clean up well. For more on these one can see:
https://en.wikipedia.org/wiki/Fire_pit#Dakota_fire_pit
Here I attempt to extend one to resemble a TLUD biochar stove. TLUD stands for Top Lit Up Draft, and is an arrangement of chambers and air flows that forms charcoal while cleanly burning the smoke produced. For more on these one can see:
https://en.wikipedia.org/wiki/Top-lit_updraft_gasifier
I dug a Dakota fire hole, then dug below one of the holes to form a char-making chamber.
It differed from this drawing in that there was no primary air supply. I guess it is actually not a TLUD, but a 'TLND' (Top Lit No Draft).
Then I loaded the chamber with dry wood, spread kindling and tinder above, but still way below ground level. Then I lit a fire atop the fuel. It burnt pretty cleanly, but released a little smoke. I'd like to improve this and will try to figure out how. Below are some photos of the resulting char in the hole.
To enlarge a photo fragment below, to see the entire image, click on each fragment.
