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How do you make biochar?

Biochar can be made from anything that was once alive, but we focus on making it from ‘waste’ woody materials like wood chips. Heating wood in the absence of oxygen is the key to making biochar.

Biochar can be made traditionally on a small scale, in bespoke kilns, or even in large kilns the size of shipping containers with lots of high-tech functionalities. 

The traditional way biochar is made is in a fire, arranged in a special way, which minimises the oxygen around the wood and prevents the charcoal turning to ash. Unfortunately this method is bad for our climate as it releases a lot of smoke, and overtime it’s also bad for the people because they end up inhaling lots of smoke in the process. ⠀⠀⠀⠀⠀⠀⠀
Biochar made in bespoke kilns, either small ones or large ones, is made at a higher temperature to improve the structural qualities of the biochar, which in turn improves the performance in the soil. A higher temperature results in a crystalline structure of carbon, so in the soil the water and fertiliser retention is maximised, and the carbon is locked up in tight molecular bonds. ⠀⠀⠀⠀
This last point means microbes cannot breakdown the carbon, so rather than being biodegradable (and releasing the carbon back into the atmosphere), the carbon instead stays in the soil and is a form of carbon sequestration and storage (hence it being carbon negative!).

Make biochar at home with purpose-built kiln

Offering a safe and sustainable alternative to traditional at-home production methods, we are the first on the market to design and manufacture a purpose-built smokeless biochar kiln

Simply load up your kiln with your 'waste' wood of choice and light it from the top. Any smoke which is generated is quickly burnt off meaning no methane pollution. 

When the flames turn blue (usually 45 minutes - 1 hour), quench the fire with water. This stops the biochar from turning to ash and creates steam, which in turn, improves the quality of the biochar. When you are sure the fire is out, put your heat proof gloves on, pick up the burn chamber using the handle and tip the biochar into a bucket. Crush it up into small pieces and then it’s ready for use!

How to ensure biochar is made carbon negative

  • Choose wood which is considered ‘waste’ or low value meaning it is destined for either landfill or incineration. By choosing clean, non-toxic wood ‘waste’ we can intercept the carbon before it has a chance to go back into the atmosphere. 

  • Make sure your feedstock is dry. Using green or wet material will create smoke which will outweigh any carbon savings achieved through making biochar.

Make your own biochar kiln: more harm than good?

It is possible to make biochar kilns at home but it can be easy to get it wrong and end up doing more harm than good. Due to the accelerated wear on the thin metal walls of most oil drums used for making kilns, these products don’t tend to have a long life. If you have the skills and the tools necessary for the job, go ahead, but be careful because you don’t want to end up creating a smoke machine. Because any smoke produced will outweigh any carbon savings achieved through the biochar. 

If you want to make your own kiln, this is one of the best resources we have come across. But please be careful… If it gets smokey, put it out with water and try again with new feedstock in a new design. Biochar should be made in a carbon negative way, otherwise, you’re doing more harm than good for combating climate change.

1 comment

  • Joakim Sjöquist

    Hi heard you in the roots and all podcast. Living in northern parts of Sweden. Gonna try to start making biochar next year. Looking into differrent way to do so. So please send me a link to me.
    Theres is a company here that just trying to start up a big scale production.

    Best regards

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