Biochar is a carbonized material produced at high temperatures in a zero or low oxygen environment. This charcoal substance has a porous cryst alline structure, and can be used to increase soil fertility (IBI 2010). Since the discovery of the Terra Preta soils of the Amazon, where biochar / charcoal incorporation is providing benefits of increased nutrients and soil CEC even after abandonment up to 2000 years ago (Sombroek et al. 2003, Glazer et al. 2002) there has been increased interest in biochar production and use.
First coined by Peter Read, biochar was envisioned to refer to charcoals which are prepared for soil improvement which would potent provide a potentially very large scale carbon storage mechanism (Read 2009).
Ideas for inexpensive light weight insulation material to fill the space between the inner and outer drums of a biochar making gasifying woodstove. This Aprovecho Research Center video shows how to make cheap/free firebricks for their rocket stoves. They mix sawdust with adobe clay and fire it. The sawdust burns away leaving a porous structure. If I fill the space between the barrels with this material, the trick would be how to let the gases and water vapor escape while it is being cured. This Brick-making experiments website adds detail. Other ideas I’d like to explore would be some combination of plaster and vermiculite or perlite.
Also Roxul Safe mineral wool used for firestopping is noncombustible, inexpensive, melts at 2150ºF, has zero flame spread, zero smoke developed rating. Available from the mech insulation supplier behind Alaska Pump (near/behind Central plumbing off intl airport road. 56th st?)