Make Your Own BioChar and Terra Preta

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Introduction: Make Your Own BioChar and Terra Preta

A simple way to make BioChar in a 55 gallon drum. Hoping to promote simple, scalable, environmentally sound methods for making biochar for improving the soil on small farms and in backyard gardens. And improving the air as well.

When you bury the carbon you are sequestering it out of the atmosphere for hundreds of years. A pound of carbon buried this way takes quite a bit of CO2 gas out of what's overhead.

http://en.wikipedia.org/wiki/Biochar
http://en.wikipedia.org/wiki/terrapreta

This is a collaborative on Instructables.com; you are invited to upload your tweaks, photos, facts, refinements.

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Step 1: Overview

Cartoon of the process. I would like to sketch some more designs and have people test them.

Step 2: Prep & Materials

Materials:
55 Gallon Drum, with Lid
Drum sealing ring
Dry Biomass - usually wood & wood chips, or dung
water
compost

Tools
Hoe, rake, shovel
Dust mask, ear protection, eye protection
Heavy gloves, boots
Hose & nozzle
Metal cutting circ saw or hammer & chisel

Step 3: Make the Charcoal

Seal up the lid and roll the drum onto the fire. You want the vent holes pointing down into the fire so that methane gases get flared off before they escape into the atmosphere, causing atmos damage.
The drum has to sit on the fire for several hours. First steam comes out for 2 to 4 hours, as the water boils off. Then, volatile gases (VOC's) such as methane and hydrogen start blazing out of the slots like blowtorches, for 1 to 2 hours. When the gases have all flared off, there will be little or no smoke. The carbon will start to burn, sucking oxygen into the barrel. That's when you want to stop the process by rolling the drum off the fire and covering the slots with sand to starve the oxygen. Water helps too, since you're happy with wet charcoal.

Step 4: Remove From Fire and Cool

Watch out for hot ground, hot sand!

Step 5: Making Biochar Into Terra Preta

Crush the charcoal with your grape smashers (boots). Add fungal wood chips, household compost, (especially milk, fish, and bones) leafy compost, chicken gickem, urine, grey water, worm tea, fish tank water, you name it! Try to get the charcoal juiced up with calcium, nitrogen, bacteria and fungus before you put it into your garden. Enjoy it for hundreds of years! The ancients added pottery shards, which may absorb toxins, but I like to use my hands in the soil, so I don't add that. Do add crushed clamshells and eggshells.

You just sequestered some carbon!

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Find out everything - International Biochar Initiative, http://www.biochar-international.org/
Hat Tip to Gunther Folke & his retort method: http://www.holon.se/folke
Join the Biochar group here at https://www.instructables.com/group/BioChar/
Check out http://www.DIYbioChar.org to participate and vote in design competitions (going live March 2009)
Take political action!

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20 Comments

 This is very helpful!  Thanks for making this Instructable.  

However, please note that THIS method of charcoal production is NOT climate-friendly.  Any combustion process that releases un-burned gases will actually exacerbate the greenhouse-effect.  The simple pyrolysis/gasification effect created in this steel drum will release gases called "volatile organic compounds" or VOCs, including methane.  This looks like smoke or fumes, and may be gray or yellowish in color.  

Methane is a gas that is 20 to 25 times more potent than CO2 in trapping heat in the atmosphere.  In other words, the effect of the gases you create while making biochar could exceed the carbon-capture benefit of biochar in soils. 

To fix this, you have two options: 
1) make certain that any gases you create (i.e., "smoke" or "fumes") are burned or flared, thus reducing the VOCs to CO and CO2 (less potent GHGs than methane).
2) even better, engineer a system to make use of these gases for thermal energy.  Waste-not-want-not!

Cheers!

This is one of the least efficient method of making charcoal and does not even guarantee that you will have any bio-char when you finish. FYI Bio-char is characterized by the presents of cations on the carbon molecules and is created between the temp. of 700C and 800C in the presence of some water. I agree with you about the climate friendliness of this method. It could be if his production process offered more control and if the biomass was destined to rot or be burned anyway. Look for this on facebook it is a good working group for bio-char production in a responsible way.

Correct wikipedia link is: http://en.wikipedia.org/wiki/Terra_preta

Thank you for your link. I found it to be both accurate and encouraging. FYI the article on wiki about bio-char is not correct on a couple of important points namely it's def. of bio-char. Here a link to a good working group on Facebook.

I first meet the founders at an international symposium on bio-char in Richland, Washington. Later I attended their workshop in Seattle, Washington, where I learned to make T-LUD stoves that had been optimized for bio-char production.

If you are burning a fire to make the biochar its releasing CO2. Does the amount of biochar you make offset this release? Would be good to figure out a simple way of capturing the syngas and re-using it to make biochar.

Thanks fyc. The carbon that is collected as charcoal is highly recalcitrant - it doesn't evaporate to the atmosphere for many years, as it otherwise would if the wood was decomposing. So there is a net capture of CO2. The syngases are directed downward into the external fire and burned to help generate heat, so they are being used to make biochar. The efficiency of the system could be improved by building an external housing that would conserve heat from the external fire and direct it around the barrel, perhaps towards a cooking platform or water jacket, and up a high chimney, perhaps with an afterburner. I hope you can improve the design and participate in biochar online forums.

Update - I added llama poop and compost to the charcoal, let it stew for a couple of weeks an worked it into my soil last fall. This year my gardens seem really happy, my friends say my stuff is bigger and greener than theirs. That's as scientific as I got right now. It's a lot of work, & it's not super friendly to the atmosphere in this lo-tech method, so I'm not recommending it for everybody.

This is very helpful!  Thanks for making this Instructable. 

However, please note that THIS method of charcoal production is NOT climate-friendly.  Any combustion process that releases un-burned gases will actually exacerbate the greenhouse-effect.  The simple pyrolysis/gasification effect created in this steel drum will release gases called "volatile organic compounds" or VOCs, including methane.  This looks like smoke or fumes, and may be gray or yellowish in color. 

Methane is a gas that is 20 to 25 times more potent than CO2 in trapping heat in the atmosphere.  In other words, the effect of the gases you create while making biochar could exceed the carbon-capture benefit of biochar in soils.

To fix this, you have two options:
1) make certain that any gases you create (i.e., "smoke" or "fumes") are burned or flared, thus reducing the VOCs to CO and CO2 (less potent GHGs than methane).
2) even better, engineer a system to make use of these gases for thermal energy.  Waste-not-want-not!

Cheers!