Biochar – agrichar – Terra Preta

This is exactly what we are doing with our CSE project. Very well done video. Only 11 minutes, please watch it!


6 Responses

  1. I just heard about this at a conference I recently attended. There was a farmer there with some forested acreage he tends for timber. He described a very simple set-up using two 55-gallon metal drums that he used to convert wood into this charcoal. He said he used trimmed branches and the brush wood that he culled from around the valuable timber crops, all under a 2″ diameter, to produce this charcoal. Any piece of hardwood above 2″ that wouldn’t bring in cash he used for his own firewood. He claimed that even pine could be used to make a charcoal that would impart no resinous flavor if used for cooking.

    We may muck about and try to reproduce his system. We don’t have all that much wood. But it would be great to either generate charcoal for cooking or for soil amendment.

    Thanks for posting the video. Extremely interesting.

  2. You could make a huge carbon filter for your tilapia pond. The pond would charge the charcoal with nutrients for terra preta, and the charcoal would keep the water clean for the fish.

    I don’t know how the charcoal would compete with the aquaponic plants for nutrients. I’ve heard that aquaponic systems can have sudden crashes in their microbe populations- a large backup filtration system would be a bonus.

  3. Thanks everyone.

    Kate – more power to you! One thing to consider is that low heat burns to create charcoal without pyrolysis runs the risk of significantly increasing emissions. Gasification runs the emissions over 1800 degree coals providing for a very hot secondary burn of the initial gases which cleans them up markedly.

    Matt – we solve the aquaponics nutrient starving concern by placing the biochar filter *after* the watercress allowing the plants to have their fill and still providing the fish with clean water.

    What my brain has been chewing on since this video is designing a dryer right into the system like they had…


  4. the dyer running on syngas was particularly impressive,

    I realize the output would be lower, but could things like corn and sunflower stalks be used instead of wood? If all we are seeking is basically high surface area carbon, it shouldn’t matter if the result is powder from relatively lower cellulose vegetation or chips from higher cellulose vegetation (wood).

  5. Absolutely – any carbon source will work. We have run everything from chicken manure to sawdust to sewage, er, “bio-solids”. The trick is to get it dense enough to sustain the temps, and chunky enough to let air in. Hence our push for pelletizing and the use of a hammer mill. That way everything from corn stover to switchgrass to cardboard can be run through with relatively little adjustments as the pellets will have roughly the same shape and density. Oak sawdust will still give more btu’s per pound than willow – but willow is alot cheaper!

  6. Hi Rob,

    I just recently started reading your blog. It is wonderfully inspiring. All this talk of being carbon negative and regenerating soils makes me want to share this with you: The Carbon Farmers of America ( They are a group of pasture-raised livestock ranchers in the Northeast who are using intensively managed livestock to stimulate grass (via chomping down) to promote root shedding, decompostion, and ultimately a regenerated topsoil and carbon sink.

    Carbon negativity and topsoil building is all possible!

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