Biochar from Brush Piles
From Kelpie's Web site: Green your Head
Since she wrote the article below, Kelpie discovered another way to make biochar from the brush pile, it's a little easier to do if like me, you get sprinkled on by rain while you're burning your pile.
"his works best with small diameter stuff less than 3 inches. Start a small fire next to your brushpile. Slowly feed it with brush so you start to build up a pile of glowing coals. You do this in layers so that once the top of the pile is hot and starting to ash (the glowing coals turn white on top), you add another layer of brush. Wait for that to heat up and then add another, until all your material is used. You should have a nice big pile of red hot coals. Now put it out with water. You could also smother it with dirt if there is no water nearby, but you must put it completely out or the coals will continue to burn and you will not get biochar."
"Another advantage of this method is that it burns much cleaner so you will get less smoke, and fewer complaints from the neighbors. "
Kelpie wrote a great description of how to make biochar from Brush Piles. for the local forest co-op:
First start with Dry Brush or Wood. (This method will be too won't work with wet wood).
"The key to the open burn pile method of making biochar is to light the pile at the top. The flame at the top of the burn pile turns the top layer of brush into charcoal. That layer then heats the layer below, driving off gases that burn in the flame. Just underneath the flame, there is no oxygen, so the charcoal layer is protected. As the pile burns down, some of the charcoal on the edges will burn, but much of it will not start burning until the pile has settled down into a heap of glowing coals. At that point, you need to protect the biochar you have made by quenching it with water. Make sure to use a light mist to slowly quench the fire, or you may get a face-full of steam and ash."
"This top-lit burn pile method of making biochar was pioneered by Dr. Tom Reed, an expert in wood gas technologies. Dr. Reed calls this burn pile method the “Pyrolysis Pyramid” method. Besides making biochar, the top-lighting method has another great advantage for brush disposal — it is cleaner than other methods because the smoke tends to burn up in the hot flame at the top. "
This method has also been described as an "upside down fire" and there are YouTube Videos under that title.