Biochar is a charcoal made from biological materials such as wood and vegetable matter. A biochar stove serves two purposes: It creates biochar and it allows you to cook food on top of it while it is making the biochar. The flame generated by a biochar stove is cleaner and less polluting than the flames that many other types of stoves produce. It burns a wider range of fuel than simple wood stoves do. It also makes biochar, which you can use as a soil amendment to make gardening easier or use as fire starters like any other form of charcoal. In addition to being clean and versatile, a biochar stove is also small and surprisingly easy to make, and it serves well as a portable camping stove.
Things You'll Need
- 33-oz. can with top removed
- 18.5-oz. can with top removed
- Short flat-head bolt, no wider than 1/16 inch, with nut
- Nail with diameter equal to that of the bolt
- Can punch
- 46-oz. can
- Can ripper
- Tin snips
- Small wire rack pot support
Hammer the nail into the bottoms of the 33-oz. and 18.5-oz. cans, in the exact center. This will make holes for the bolt, so you can connect them later.
Hammer additional holes all over the bottom of the 18.5-oz. can, spacing them not more than 1/16 inch apart from each other. These holes will draw air into the burn chamber from underneath.
Punch twelve holes around the bottom rim of the 33-oz. can, using the can punch. These holes allow air intake from outside the stove.
Place the smaller can inside the larger one, so that the center holes in their bottoms line up. Bolt them together.
Cut the 46-oz. can in half with the can ripper. File the jagged edges dull with the file.
Punch a hole in the center of the base of one of the half cans, using the nail. Use this hole as a starter hole, and cut out a 5/8-inch-wide hole with the tin snips.
Set the large half can over the cans you have bolted together so that the hole you cut is on top. This half can is the top of the stove. Place the wire rack pot support, sometimes called a trivet, on top of this half can. This device is meant for holding pots over an open fire, it can be as simple as a metal grate supported by metal legs. If you cannot find one small enough to fit on top, use one large enough to fit around it so the wire rack is suspended directly over the hole in the top of the stove.
Tips & Warnings
- Fill the inner can with biomass such as wood chips, leaves or pine cones. Ignite the biomass directly with matches or by igniting a cotton ball soaked in alcohol placed on top of the biomass. Place the stove's top over the two-can assembly once it is lit, and follow with the rack on the very top. About a half-cup of biomass will boil 1 quart of water. Once the flame goes out, remove the pot and the top of the stove, and douse the contents with water. This prevents the charcoal from burning up. Save the charcoal for later use.