Biochar
Create Biochar with the Trans-Portable Kiln Method.
We have made it our mission to improve the Portable Metal Kiln charcoal-producing-kiln and investigate ways to turn it into a biochar producing kiln. This system uses a ‘direct combustion’ method, whereby the heat for carbonisation comes from burning a portion of the biomass feedstock in a limited air environment. Vuthisa however decided to promote the plans for this basic drum system of producing charcoal and biochar so that others can build it and improve upon it. By constructing a standard kiln everybody is immediately on the same page. Join our exclusive community of Portable Kiln owners, known as the Portable Kiln Google Group for sharing ideas, innovations and improvements.
To produce biochar many enthusiasts opt for the 55/30 system, which consists of a 55-gallon outer drum containing the fire around a 30-gallon inner drum acting as the enclosed retort. For examples of such systems visit: http://www.carbon-negative.us/Burners.htm and http://youtu.be/COPqvVH7jiw. To produce biochar, the Trans-Portable Biochar Kiln can be constructed from either 3 (current model) or 4 (improved model) standard (2.350 x 1.225 metres) mild steel sheets. Recent trials have confirmed that it is possible to clean up emissions of the Transportable Kiln and convert it to a retort system. Our conventional Transportable Kiln can accommodate 2 x 55 gallon drums for making biochar with indirect heating, but we have been collaborating with experts in the fields of biochar and they proposed a 3-drum retort. This allows more fuel to be added in order to heat up the inner retorts, plus there will also be a notable increase in the biochar yield per burn.
Click on the GIF image above to play the animation
The drums are wedged in side by side and is rolled along with the rest of the kiln. When not using the 55-gallon drums the system is not a true retort and produces more smokey burns. If the purpose of the operation is to clear invasive aliens then the open burn will be able to process more feedstock at a time. If the focus is on creating a clean burn and producing biochar to be used as a soil amendment, then the enclosed drum system may the way to go even though the yield will be less. Compared to the 55/30 system the yield is substantially more though. The Trans-Portable Kiln is easy to transport to the work site for assembly, and being circular in shape, can be rolled over fairly long distances with minimal effort and labor. It is a fairly low cost system and initial capital outlay is minimal compared to other commercial type kilns. We have been able to increase the longevity of the kilns, by increasing the gauge thickness, reinforcing the top and bottom of the kilns to make them more structurally secure when re-positioning the kiln. We also have strict guidelines for setting-up procedures, feedstock re-fueling, and general handling of the kilns.
What exactly is Biochar?
Biochar* is charcoal created by pyrolysis of biomass, and differs from charcoal only in the sense that its primary use is not for fuel, but for biosequestration or atmospheric carbon capture and storage. Charcoal is a stable solid, rich in content, and thus, can be used to lock carbon in the soil. Biochar is of increasing interest because of concerns about climate change caused by emissions of carbon dioxide (CO2) and other greenhouse gases (GHG). Carbon dioxide capture also ties up large amounts of oxygen and requires energy for injection (as via carbon capture and storage), whereas the biochar process breaks into the carbon dioxide cycle, thus releasing oxygen as did coal formation hundreds of millions of years ago. Biochar is a way for carbon to be drawn from the atmosphere and is a solution to reducing the global impact of farming (and in reducing the impact from all agricultural waste). Since biochar can sequester carbon in the soil for hundreds to thousands of years, it has received considerable interest as a potential tool to slow global warming. The burning and natural decomposition of trees and agricultural matter contributes a large amount of CO2 released to the atmosphere. Biochar can store this carbon in the ground, potentially making a significant reduction in atmospheric GHG levels; at the same time its presence in the earth can improve water quality, increase soil fertility, raise agricultural productivity and reduce pressure on old-growth forests.
Preparation of biochar
After browsing through many resources on techniques to prepare your biochar before mixing it with the soil we found Peter Hirst (New England Biochar) gave the best instructions: “The biochar has a micro-porous structure and it also chemically attracts organic molecules and water and tends to hold them in place. To make them available for the plants it has to be soaked or saturated with all of those elements before it goes in the ground otherwise it will be competing with the plants for the water, the microbes and the nutrients and it can actually harm the plants if it goes in raw. So we advocate mixing the biochar with soil or a good active organic compost before it goes in the soil so it soakes up its full compliment of water and nutrients and microbes so that it can make those available immediately to the plants as soon as it is added to the soil. Ultimate concentrations after some time of repeated applications of biochar will work up to about 8 to 10% biochar by weight of the soil content.” Since this system produces approximately 265 lb (120 kg) of biochar, you would eventually be able to enrich an area of approximately 250 ft2 (23 m2) or 2860 lb (1300 kg) of topsoil.
For expert hands-on advice buy The Biochar Revolution. Chapter 8 is especially relevant and gives the best advice for characterizing Biochars: attributes, indicators, and at-home tests written by Hugh McLauglin, PhD PE, Director of Biocarbon Research, Alterna Biocarbon Inc.
To see more benefits of biochar as a soil amendment see this post: http://vuthisa.com/2011/01/09/biochar-as-a-soil-amendment-and-carbon-sequestering-tool
See this video clip of some Biochar created with the above system: http://youtu.be/PRdYW5klHXc
The process – explained
Now that we know how to make biochar, what thermodynamic reactions are actually taking place during the different stages of biochar making? Knowing this might help you to gauge your own operation and fine tune it. It is a good idea to invest in an industrial purpose, digital thermometer and Type K thermocouple rod ±0.5 metres (1.6 ft) long. This will cost approximately $200 (USD).
The pyrolysis of wood in such apparatus basically resolves itself into 4 different stages:
- Evaporation of the moisture present in the wood takes place as the initial phase, up to an average temperature of 170 °C (338°F). During this period scarcely any gas is produced.
- As the fire builds up inside the kiln, the temperature rises and at approximately 280 °C (536°F) the exothermic reaction begins to take place. Gas consisting almost entirely of carbon monoxide and dioxide is evolved and a certain amount of acetic acid is formed together with small quantities of wood-naphtha and tar.
- The exothermic reaction then continues during which concentration of carbon in the biochar takes place. Large quantities of hydro-carbons, acetic acid and wood-naphtha and tar are produced while the temperatures rise to 380 to 400 °C (716 to 752°F).
*As per Terms and Conditions of Wikipedia Encyclopdia we attribute credit to the authors on Biochar by listing their URL and hyperlink here: http://en.wikipedia.org/wiki/Biochar
Make charcoal in your own backyard « said,
June 12, 2010 @ 9:23 am
[...] Biochar [...]
Is it better to burn wood or charcoal? « said,
September 5, 2010 @ 12:28 am
[...] Biochar [...]
Welcome « said,
October 28, 2010 @ 3:36 pm
[...] Biochar [...]
greenpower said,
December 28, 2010 @ 5:12 pm
I agree “The Biochar Revolution” with “The Biochar Solution”
http://biochar-books.com/ is pretty cool.
The Biochar Revolution collects the results and best practical advice that these entrepreneurs have to offer to the biochar community. When practice and theory advance to the point where they meet in the middle, then we will truly see a biochar revolution.
Biochar as a soil amendment and carbon sequestering tool « said,
January 9, 2011 @ 9:40 pm
[...] Vuthisa investigated the Portable Metal Kiln for biochar production, which differs from conventional open burn methods in five ways: (1) The steel plate is very thick and not only lasts longer than 55 gallon drums, but allows the contents of the kiln to “cook” in the absence of charcoal by means of a tight sealing lid (2) The drum can be made oval to fit in two seal-able 55-gallon drums, yet also allow burning material to be added to heat the drums (3) Small sized feedstock, typically found in yard waste, such as twigs and branches are ideal for this system as it will not turn to ash, as with larger horizontal type kilns that can take up to 3 days to cool down, reducing small diameter feedstock to ash (4) Large quantities of biochar can be produced as opposed to the 55/30 type closed retort that produces small quantities (5) The kiln can be rolled long distances without any wear and tear to adjacent feedstock sites. More information and detailed construction plans can be found here: http://www.vuthisa.com/biochar [...]