Biochar is made with high heat and low oxygen. This was an experiment of sorts. I started the fire after packing the barrel with wood and once a fire had started on the top and the coals spread around, I tilted the barrel to provide a rolling effect for the gasses that the wood compounds give off to ignite. You can do also make it with a standard barrel and just keep adding to the fire right at the point where the burned wood shatters when tapped and is starting to ash. A cone shaped kiln is even better at making it, but either more expensive, or harder to make.

My future plans are to procure a 30 gallon barrel with a lid that I will pack full of material to turn into biochar and then place it in the 55 gallon drum with some air ventilation holes and a tall chimney to make a rocket burner. The inside barrel will never catch fire, but will get hot enough to pyrolyze (offgas) and my end result will be much better and a much higher percentage.