Making Biochar using Dry Mulch (video)


  • Making Biochar using dry mulch
  • Mulch is loaded into an old beer keg
  • This material will pyrolyse and become biochar
  • This keg can hold 50Litres
  • 50L mulch yields ~30L biochar
  • This lid is from another keg, but you can improvise
  • Sorting out the ash from the previous burn
  • Some bricks to support the keg
  • These kegs are farkin’ heavy!
  • The keg goes in upside down, so gases come out the bottom (into the fire)
  • More mulch is used as a fuel stock for burning
  • This mulch will burn from the top, down around the outside of the keg, cooking the mulch inside
  • A bracing made from strap steel, to hold the lid in place. It also allows some air in.
  • Cardboard is an excellent starter fuel, but the ash can block airflow, so don’t use too much.
  • The chimney stack creates draw, sucking air up through the holes at the bottom of the barrel
  • It took me 15mins to set up this burn.
  • Start the burn!
  • It has been my goal to minimise smoke during burns. Unfortunately, much smoke has been created in this pursuit.
  • The two most important factors (of many), are
  • 1: Adequate air intake
  • 2: DRY feed stock and fuel stock
  • A slow start and a long stack also helps
  • No smoke!
  • The fire makes it’s way slowly around the top
  • It is drawing air through the mulch below it
  • The heat begins to cook the mulch just below…
  • …and the fire is able to burn downward
  • Still no smoke!
  • Notice the darkening of the barrel as it heats
  • ~25mins into the burn
  • ~35mins
  • ~45mins 
  • Still no smoke!
  • This is a burn at night
  • While it looks awesome, it’s not burning clean
  • There is more fire inside than the barrel can ‘process’, and so smoke is pushed out the top
  • …still, it looks awesome
  • After the burn (a few hours later)
  • There appears to be less material but it has shrunk
  • If the biochar is too hot, it can start a fire, so be ready to hose it down thoroughly
  • Biochar, when added to soil, holds water, nutrients and provides homes for bacteria and fungi
  • It continues to support soil fertility for 1000’s of years!
  • To me, that makes it well worth the effort
  • …plus I have an excuse to play with fire!
  • Ready for another round
  • Thank you for watching

Read the full article here…

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