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Small scale Biochar with DIY retort

Small scale DIY retort

Any fire proof container will work in this technique.  The feedstock is placed inside a container, well-sealed, with a small hole punched near the side of the lid to allow gas to escape and prevent oxygen entering.

  1. Start a fire the size of your container or bigger. It is best if the hole for gas to escape is in the fire, as it allows the gas to be burnt off and not escape into the atmosphere.
  2. You will know the feedstock has been pyrolyzed (turned to Biochar) when there is no longer a flame from the hole in the container. It’s best to leave it a little longer to be sure all volatile matter has been released.
  3. Carefully remove the container of charcoal while still hot and dump into a suitable container of water. This causes the Biochar to become hydrophilic and absorb water. This is a must if you with to inoculate the Biochar before you add it to soil. Once no more Biochar is floating on the surface, it has been successfully conditioned to be hydrophilic.
  4. The best texture for soil addition is as fine as possible. You can use a mortar and pestle or grade it through a screen, anything works – the finer the better.
{ 3 comments… add one }
  • Charmaster Dolph March 15, 2016, 8:48 pm

    Hey Charlie

    Feedstock means the wood/biomass that you want to make into biochar.


  • Jerry Bouin February 15, 2017, 8:00 pm

    Hi Dolph,
    I’ve got two questions:
    1} When I do my bamboo biochar {end process}, I fill an empty drum that I turn over to stop oxygen ! I don’t dump it in water ! does it matter for it’s quality ?
    2} I’m looking to make a bigger biochar burner to install on a trailer and be able to process 3 metres long bamboos of big diameter ! Would you have any drawings for making such horizontal burner ?
    Thanks in advance.

  • David August 31, 2017, 12:46 am

    Could this be done in an inside fireplace using a smallish tin? Would the gasses be an issue?

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