The Backyard Biochar Retort Kiln

The Backyard Biochar Retort Kiln This low cost wood-fired biochar kiln can be even cheaper if you have some of the materials already lying around or if you have welding skills. The kiln uses any small dimensioned, dry feedstock that won’t pack together -... More

The Backyard Biochar Retort Kiln This low cost wood-fired biochar kiln can be even cheaper if you have some of the materials already lying around or if you have welding skills. The kiln uses any small dimensioned, dry feedstock that won’t pack together - sawdust or wood chips are too small. Wood chunks, sticks or stalks will work better. The feedstock needs to be loaded into the retort with air spaces so the gas can vent. Depending on the feedstock, you can make 20–40 lbs of charcoal in 2-4 hours. How does it work? The 55 gal drum is the retort. It is loaded with feedstock and then sealed, except for the vent. The retort is surrounded by a kiln made of cement blocks, to hold in the heat. You build a fire underneath the retort and keep it going for about an hour until the hot wood inside starts to outgas. The gas vents through the tube under the retort and ignites. Once the gas is burning, you can stop feeding wood to the fire as the reaction is now self-sustaining. This proc Less