I can’t find the video (it is posted here somewhere) but they do commercial production in a country and the retorts looks similar to this one except they seal the top and lets the gases come out the bottom and sustains the heat. But they get it going with waste oil and wood.
and if you want to do it that particular way, then you might look at waste oil burners for foundries and they can get hot enough to melt steel.
I personally just use a little bit to soak into the kindling to get the fire started.
The video above does show how crude a setup works… A drip oil burner would turbo charge the setup.
I have been doing experiments with sand batteries, I found that if I put wood ins the sand it will char… I am using a dutch oven and a stove top burner using solar panels to power it.
I love new ideas. Looking at this I would rather have a hole dug into clay in the ground so one would not be going thru 55 gal barrels so often … for the outer shell.
I don’t think the commercial ones use drip, they used a pan of it. more like a petroleum jelly can, iirc. Once you get it heated up, it should self-sustain. Having fire on the inside maximizes the volume of the barrel.