28 July 2009
MAKING BIOCHAR: with Peter Hirst of New England Biochar
Peter Hirst brought his 70 gallon stainless steel biochar retort to Warner, NH and showed us how to burn 100 pounds of wood into 30 pounds of biochar. That's enough for a few beds in our garden after we grind it up and mix it with an equal amount of compost to innoculate the biochar with soil bacteria. But the biochar pioneers are scrambling to find economical and efficient furnaces that can produce tons of the material.
Biochar was first discovered by Amazonian Indian societies a thousand years ago (terra preta), and rediscovered a decade or so ago by modern cultures desperate for ways to improve soil fertility. The new biochar retorts, such as this one that Peter demonstrates, burn biomass with high efficiency and also produce charcoal which can be added to soils, sequestering that carbon more or less permanently. The secret is wood gasification. For more curiously local perspectives, visit http://curiouslylocal.com