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Biochar made easy!
Posted by Jesse Leavitt about 10 years ago
Possibly the easiest, fastest, and most efficient method for producing biochar
For those of you who read my last update, you could see I was initially demorilized about the methods of producing biochar. It had required high input of fuel, and material that some people might just not have the sources for. Although the end product was of high quality, it didnt seem worth it to me. I was determined to find a more efficient way.
After leaving the permaculture research institute, I found my self volunteering on a 150 acre property just west of Brisbane. The property owners were an older couple attempting to reforest, and rewild their property in the gatton valley. Wynton (fellow intern) and I arrived and our first thoughts for assisting mark and Diane with their efforts was to put together a high quality compost. Better yet, biochar charged with the inoculum compost.
Mark and Diane were excited about biochar, and how it would benefit their property. Now the trick was to use materials they had on the property to produce the char. After rummaging through their farm shed, I found a 44gal barrel. I thought to my self "there has got to be a way to just use this barrel" and in fact there was! The key idea is what is called an upside down fire. By cutting a hole in the bottom of the barrel giving the barrel two open ends, allows you to burn from top to bottom (see photo 1) With the barrel mounted slightly above the ground to let oxygen in the bottom of the barrel drawing the flame down. (See photo. 2) This causes the flame to ignite volitiles from the biomass, and leaving char behind because of the rapid combustion. (See photo 3) after about 5 minutes all volitiles have combusted and it is time to extinguish the flame. (See photo 4) leaving you with the remaining material, biochar! After using this method, I came to the conclusion that farm scale biochar was worth it, and highly useful. It took no more than thirty minutes to prepare and process, also the fuel itself created the char. Afterward we assembled a compost pile, and mixed in a few handfuls of char. (See photo 5) Now Mark and Diane have a high quality product to assist them in their efforts! I recommend going out and trying this technique yourselves and putting it to good use! Soon I'll be seeing how I can utilize biochar in fiji..so stay tuned for my next update!
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Is there a separate chamber in the drum to make the biochar?
No, that's the beauty of it. You only need one drum, with an opening on top, and bottom of the barrel. The upside down fire allows the material to burn in a state of pyrolysis.This process is more efficient because the fuel to lite the fire is the same material that is being turned to biochar.
Wow this is awesome. I wonder how this can be biochar and not just regular burnt wood, I wonder if it has the surface area of biochar. Well I trust you and I hope there can be some analysis done on this method compared to the standard duel container method. Have fun in Fiji brother.
Very interesting. So you think this method uses up the oxygen at the ends not allowing any (oxygen) to the rest of the barrel?
Did you cut the bottom OUT or just put in a hole on it? I have used a "burn barrel" for many years and spread the ashes out, but it's mostly paper in there. To use branches, leaves, old hay, etc., 1-how does one keep it from falling out of the bottom and 2-what materials are best to use to create the char?
Heat energy actually radiates equally in all directions from the point of combustion. it’s the displacement of gasses as they expand that sends out hot air not the actual heat energy itself. So once combustion of the top layer of your upside down fire occurs, the heat energy is radiating down as much as it is up. So if extinguished at the right time you will end up with biochar.
Marie- I cut out a hole in the bottom 10 centimetres from the edge of the barrel. The material is stacked from the ground up. The barrel must be packed tight with as few air pockets as possible. I find the best material to be bamboo, with sawdust and leaf litter to fill in the gaps.
If you are making biochar you need to try and deal with the emissions the best way possible. More than carbon is burn and released. Adding a long flue will help and if you can create flue turbulence that will help burn up more of the negative emissions.
This is a video of an open source project based on my design. A lot of effort has gone into reducing emissions and making the unit safe and easy to operate and maximising the biochar produced.
This is a nice version of the unit. (UK)
This is my hacked R&D version. (based nth of Brisbane)