Simple biochar maker for any earth oven, masonry heater or fire place

Discovery this weekend! I was watching a video on YouTube by user hiramcook (the link is: http://www.youtube.com/watch?v=G-D766o4nQU&NR=1&feature=fvwp) and got an idea for a super simple biochar chamber to add to any existing earthen oven, masonry heater, or fireplace such as a Rumford or even a conventional one. It takes about 90 seconds to make if you are being especially lazy and slow.





What you need is:

1) A steel can with a steel lid that fits tightly. Best to remove any paint, but I skipped that part :) No exact size, just small enough to fit into your earthen oven, fireplace, wood stove fire box, etc. What I am talking about is the type of can that carmel popcorn, holiday gift cracker or cookie assortments, and the like are sold in and you can usually find in a thrift store or at a garage sale, if not in trash piles, metal recycling bins, etc.

2) A fat nail, slotted screwdriver, awl, or something else to use for punching holes in the lid. Hole size and number are probably not important, as long as they are in the lid. My test chamber has six holes arranged in a circle in the center of the lid, each about a pencil thickness wide, kind of like a burner.

3) Dry twigs and/or wood chips, generally 1/2 inch or less in diameter, broken up by hand and dropped in the can. No need to make them all uniform or especially short, just snap bunches of them down into finger length or smaller bits and fill the can. You will wind up with lots of air space around them, which is good.

Put the lid on the can. Punch holes in center. Take lid off. Fill with twig and chips. Put lid back on.

Now put the can in the fire or on coals inside your earth oven, wood stove, fireplace etc. with the lid and holes up. As the can heats up, the pyrolysis gasses are driven out of the holes, where the surrounding fire ignites them. Keep an eye on the can by checking the flames periodically until they stop. When they stop, remove the can, which is now full of biochar! It may be a good idea to put a brick on top of the holes to make sure air is cut off and the charcoal inside does not continue to burn. When the can is cool, open it to get to the biochar. This stuff is fluffy and shiny and simply falls apart in your hand. Put it in a bag and crush it before adding it to your compost pile or composting toilet - the bag will keep the charcoal dust down.

Simple and cheap and fast and effective! The can can be re-used for a long time. The photos include shots of it in use in my earthen oven, taken through the removable plug of my oven's rocket door (see previous shovel tech post). Yes, those flames really are coming out of the holes of the can, the photos don't show it as well as I hoped. The proof is in the char. Please make some biochar!