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Workshop discussion and documents (in progress)

Biochar is a charred substance which is thermochemically treated in a zero or low oxygen environment. Charcoal generally refers to wood biochar, but other biochar can also be produced from other biomass, and even processed biomass (e.g. paper mill waste). Generally biochar refers to those substances which are prepared, or have properties suitable for either as an agricultural soil amendment or for carbon storage. Biochar is not the same as ash – a product of full combustion of biomass, including combustion (with air) of biochar. This has a lower stable carbon content, although is likely to have more available nutrients.

Biochar has been defined as “the porous carbonaceous solid produced by thermochemical conversion of organic materials in an oxygen depleted atmosphere which has physiochemical properties suitable for the safe and long-term storage of carbon in the environment and, potentially, soil improvement”. Shackley, S., Sohi, S.P. (Eds.), 2010. An assessment of the benefits and issues associated with the application of biochar to soil. Report to the Department for Environment, Food and Rural Affairs and the Department of Energy and Climate Change, London.

“Biochar is commonly defined as charred organic matter, produced with the intent to deliberately apply to soils to sequester carbon and improve soil properties (based on: Lehmann and Joseph, 2009). The only difference between biochar and charcoal is in its utilitarian intention; charcoal is produced for other reasons (e.g. heating, barbeque, etc.) than biochar.” Verheijen FGA, Jeffery S, Bastos A.C, van der Velde M, Diafas I (2009) Biochar Application to Soils - A Critical Scientific Review of Effects on Soil Properties, Processes and Functions. EUR 24099 EN, Office for the Official Publications of the European Communities, Luxembourg, 149pp. (Lehmann, J., and Joseph, S., eds. (2009). Biochar for Environmental Management: Science and Technology. Earthscan, London)

”Biochar is a fine-grained, highly porous charcoal that helps soils retain nutrients and water. The carbon in biochar resists degradation and can sequester carbon in soils for hundreds to thousands of years, providing a potentially powerful tool for mitigating anthropogenic climate change.” IBI (2010) International Biochar Initiative: http://www.biochar-international.org/press

“Charcoal and Biochar are similar, but not the same. They share raw materials and production techniques, but they have different end uses and those end uses utilize different properties in the chars.” Schenkel and Shenxue revisited - implications on char production and biochar properties Version 1 (June 2010) issued at the Biochar2010 Conference, Ames, Iowa – June 2010 Hugh McLaughlin and Frank E. Shields

Charcoal can be any biomass see charcoal for more information about their relative properties including heating value.

The term biochar originated in the bioenergy literature in the late 90's to distinguish grain-derived activated-carbon from similar coal-derived materials. The two concepts of using charcoal as a soil improver and as a GHG mitigation strategy arose separately in the early '90s.

The matching of the term “biochar” with the climate-change mitigation concept did not occur until 2005 in a presentation by Johannes Lehmann entitled “Bio-char sequestration in soil: A new frontier”. Lehmann relates that the term stemmed from a discussion he had with the late Peter Read who coined the phrase in this context http://www.guardian.co.uk/commentisfree/2009/mar/27/biochar while working on the revisions to one of these publications and preparing the 2005 presentation. See http://www.nature.com/ncomms/journal/v1/n5/extref/ncomms1053-s1.pdf for the references behind this timeline.

Terra preta refers to anthrosols (human modified soils), examples of which were first investigated in the Brazilian Amazon. Biochar, charcoal, ash and other substances were incorporated into the soil to make these dark earths. This happened over a long time period, and the methods and additions are unknown, which makes it not completely comparable to modern biochar addition, although lessons can be learned, and they can try to be recreated to realise the same benefits to plant growth which they show.

Biochar crop trials in Asia Pacific (and beyond...)

- It contains little nutrients and because the biochar is hardly decomposed, most of the nutrients are not available to plants.
- lack of evidence that this has potential for povery alleviation for use by small farmers
- husk char has good physical characteristics like water holding capacity but that is not very important in rice soils.
- husk char does not decompose well, which allows carbon sequestration in soils
- husks belong to millers not farmers
- drive could be carbon sequestration rather than soil improvement?
  • Australia
- Field trials are being conducted in soils ranging from tropical oxisols to sands, with a range of biochars (different feedstocks and process temperatures). The project also includes characterisation of biochars, and studies on carbon turnover and nitrous oxide impacts, and herbicide retention. This national project and other work is listed at http://www.anzbiochar.org/projects.html
- Generally, we have seen very positive effects on plant growth from manure-based and paper sludge chars, especially in acid soil, and less response to wood waste chars. But the wood-based chars have much slower carbon turnover, and give greater reduction in nitrous oxide emissions.
- Older published work is listed at http://www.anzbiochar.org/links.html#publications
The most recent volume of the Australian Journal of soil research is a special issue from the 1st Asia-Pacific biochar conference, held in May 2009 http://www.publish.csiro.au/issue/5422.htm
  • Indonesia - Rice BiocharRiceKalimantan.pdf
  • Malaysia - Maize Biochar Maize Study UMS.pdf
  • Lao & Vietnam - rice husk biochar trials http://www.mekarn.org
  • Japan - Tokai University, Bamboo charcoal for tea trees
  • Oil Palm waste, National University of Malaysia (UKM) and Malaysia Palm Oil Board (MPOB) Malaysia, suitable for orchids/palms/trees/shrubs/flowers/vegetables. BEK from ALL Power Labs, BEC from Biochar Engineering, UPM-Nasmech Carbonator Pilot Plant in Malaysia. Using EFB, fronds, trunks and shells to produce biochar.
  • India - GEO – tree crop trials, http://www.e-geo.org, soil added to pit where mango saplings planted, and also a biochar-compost used as a mulch
  • India - Geo http://biocharindia.com vegetable trials: biomass of a variety of crops generally improves with biochar. More nitrogen is required initially with biochar addition to the soil.
  • USA - (for alkaline soils research) http://www.biocharengineering.com/about_us/index.html; University of Colorado at Boulder - North American Biochar Conference http://cees.colorado.edu/biochar_soils.html

Biochar use

  • Waste charcoal (rice husk) in Thailand is being applied to coconut palms
  • Charcoal / activated charcoal can be used in nurseries, as a plant and tissue culture medium (absorbtion of secondary metabolites - which are growth inhibitors), as a "soil and mulch sweetener", and as a fertiliser and insecticide
  • Small-scale farmers in India, char and ash is commonly added for eg. links in http://biocharindia.com
  • Biochar urinals: At GEO we have designed simple Biochar Urinals please see the link http://e-biocharurinals.blogspot.com/. Value addition and utility of Biochar in our daily life makes it more valuable. Recently we encouraged a farmer to spread the Biochar in the cattle shed for keeping it dry and clean as well for serving the purpose of Absorbtion urine of cattle. Waterless cleaning of utensils using biochar, the oil and other substances attached to Biochar adds value and serves the purpose of cleaning too. http://e-biocharclean.blogspot.com/. A good presentation on urine http://conference2005.ecosan.org/presentations/tidaker.pdf

Charcoal production vs biochar production

  • Best economic return for charcoal production is shown for a Heat Treatment Temperature (HTT) of 300-350 oC. Preferred biochar production range, based on optimized 'Adsorption Capacity', is shown to be 450-700 oC peaking at 600. (ref. frank shield’s paper – see above)

Available technologies

  • Sampanda, Anderson's TLUD, EverythingNice, Anila gasifier stoves research http://biocharinnovation.wordpress.com/
  • Flannagan stove - China http://www.airpollutionfacts.net/2010/10/17/rice-hull-biochar-trial-hangzhou-2007/
  • TLUD comparison paper Anderson_Stove comparison tlud.pdf
  • TLUD Biochar producing stoves from GEO Magh series http://goodstove.com/
  • Efficiency vs char production: A good TLUD cooking stove will give from 20 to 50 gram of char from 1kg of fuel if you let it burn out. If you stop the process when flame is over it will be from 50 to 100 gr. A bad TLUD stove almost the double, but then loosing energy for cooking.
  • Magh series, designed more than 25 TLUD stove designs including natural draft and forced air, all the declared as Open Knowledge http://goodstove.com
  • TLUD adoption is slow as the technology is different from traditional stoves, its operation/use requires training to the stakeholders
  • The price of stoves varies, could be made for just 4 cents to $100 or more. The adoptable model for a family of five could be made using locally available material at the cost of $7 natural draft and $10 forced air.
  • The pellet TLUD stoves are dependent stoves, although their performance is good, their adoption is low, the recurring cost on pellets is not bearable by many low-income communities. The facilitation, awareness, cost of stove, preparation of fuel / fuel cost and training on their operation are the major challenges. But their efficiencies being higher about 40% would be in large demand.
  • The TLUDs for institutions and community cooking are in immediate demand, if proper designs are made and facilitated. The biochar as byproduct, unless the community feels its importance and usage, are not ready to take it out of the stove and quench it.
  • Most often the user is leaving the biochar with in the stove for simmering / extra energy.
  • Does anyone think it will be possible to encourage the use as a soil amendment or is it not in the interest of users to do this?
- desire for use requires that stove user has land, which is not optomised for cultivation (unless someone is in the business of buying it, although this has been seen on a small scale for ironing in India). Also that the user does not get fuel for free already or which is readily available. The benefits of biochar have to be known, and also successfully realized (biochar will have to be added at the right season, and in combination with other soil conditioners). Has to be full information then free choice of user.
- It is difficult to send an accurate message to users about the benefit of biochar, if they investigate themselves, the change they see may be due to other reasons, and not due to the biochar (i.e. controlled with and without biochar trials are used – these can be simple).
- The extra effort to put the biochar into the ground is also a disadvantage, and biochar / ash from fires has competing uses for example in toilets.
  • Should we even be trying to maximize biochar production in stoves (which reduces efficiency) or trying to ensure efficiency and emissions reductions (which have proven to be very good in gasification stoves anyway)?
- The stove must fit the needs of the user, so some biochar producing stoves should be available. But biochar producing ability must not be at the expense of ease of use.
- Feedback from users is required.
- Gasification stove should be promoted because they can use materials not used in traditional or conventional stoves (biomass waste).
Biochar can however be beneficial, so can be stored by users, in a metal container (another expense…).
- TLUD stoves are also not designed for char production, so it can just be seen as an option of the user wants to empty the stove. Actually emptying a stove is difficult – the stove is hot, and it is dangerous and difficult to extinguish (especially when you are in the middle of cooking!).
- The TLUD-FD (Forced Draft = with fan) does not produce any char, but the benefit of this design is in the emissions reductions and efficiency.
  • Stoves and char removal: Quenching with water in a metal stove - can induce rusting I think depending on the type of metal used, which shortens the life span of the stove?
  • Competing uses for char from stoves in the United States and Europe in the 1800s, charcoal was mixed with "nightsoil" and sold to farmers as "poudrette" http://timespanner.blogspot.com/2009/08/new-lynn-poudrette-factory.html

  • Gasolysis unit India - picture awaiting upload...
  • Gasification is an important technology, espc. of rice husks since there is an unusally high char and stablised carbon yield compared to other woody biomass (may be due to the silica shells which seem to protect the carbon in the biomass from conversion). Feedstock is free and where it is for waste management, it pays for its self
  • Negative consequences are limited and can probably be avoided (e.g. tar production in the gasification, health issues from rice husk burning where this is feedstock)
  • Gasification in Cambodia - energy is expensive so it makes economic sense, and rice husk is readily available
  • Torrefraction converts biomass to use in co-firing power plants or dedicated biomass combustion

POI (Palm Oil Industry)

  • Biochar can benefit: (fertilizer efficiency, crop enhancement, biomass waste management, CHP/WtE, greenhouse gas emission management, river eutrophication management, environmental spin)
  • the POI has readily available feedstocks in large quanitities which could be used to make biochar
  • The POI is likely to continue, so efforts can be made to make it more sustainable.

Biochar characteristics / characterisation

  • we may produce biochar for carbon management, or agricultural
  • it is possible to produce differenet characteristics with biochar using feedstocks primarily, but also through process conditions
  • probably not practical in small scale / low tech approaches to change process
  • Stephen Joseph presentation covers the aspects that should be assessed in characterising biochar, from health and safety to effectiveness as a soil amendment http://www.ibi2010.org/wp-content/uploads/Joseph_characterization.pdf
  • analytical techniques for characterising biochar and presents data for a range of chars http://www.publish.csiro.au/nid/84/paper/SR10058.htm


  • PAHs???
  • The IBI advised that when using high silica feedstocks such as rice husks, 'it is important to keep the temperature of pyrolysis low (below 550 degrees C for high silica feedstocks such as rice husks) to reduce likelihood of forming crystalline silica.
  • IARC: “There is sufficient evidence in humans for the carcinogenicity of inhaled crystalline silica in the form of quartz or cristobalite from occupational sources. There is inadequate evidence in humans for the carcinogenicity of amorphous silica”, page 210 (IARC, 1997) - IARC, 1997. Silica: IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. International Agency for Research on Cancer, Lyon, 242 pages.
  • still a lot of investigation to be done, but there can be no doubt that amorphous silica can cause health problems.
  • Adriana Downie's presentation on conference website has dioxin data. http://www.ibi2010.org/wp-content/uploads/Downie_-_ibi_2010_-risk.pdf
  • Specifiying temperatures alone can be misleading, because crystal formation is a function of temperature and time at temperatures below 1200 deg C and times of the order of minutes. This is a moot point with slow pyrolysis, but is significant with fast pyrolysis.
  • The presence of iron and other similar metals is useful in encouraging the formation of low melting point silcates (especially under reducing conditions), which tend to be less crystalline than silica because they melt and often solidify as amorphous silicates (depending on the cooling rate). For things like rice husk the intentional addition of collodial iron to the feed may (emphasis) help in reducing formation of crystalline silica
  • Carbon traps in the pores of plant derived silicate structures during gasification. This may (emphasis) make it less of a health risk by making it easier to assimilate by the body.

Feedstock availability

  • Malaysia & Indonesia – POI
  • India Agriculture biomass available in India is about 800 million tons. Crop residue is as follows (in million tones): Rice (13.1), Wheat (15.4), Sugar(21.6), G.Nut (3.3), Mustard (4.5), Cotton (11.8), Total 69.9 million tones crop residue from the above six major crops. Current use is as compost or burned into ash.
  • Feedstock Rice husk in Asia Pacific: use of rice residues (straw and rice husks) is an interesting scale to look at, since there is lots of it available, in many cases it is not used, and its use does not interfere with food production (one competing use is charred husks can be mixed with fresh husk to produce fuel briquettes).
  • Eucalyptus spp. has a very high productivity, and Moringa spp. and Jatropha curcas are potential tree crops with residues (competition is biofuels)


  • extended abstract from IBI focuses on learning from the experience of the bioenergy industry (biochar, policy, carbon offsets) cowie et al.doc

Carbon finance

  • Small scale biochar production is efficient and cost effective is compared to other means of carbon sequestration. But because there is no time to buy, both large and small scale options are required.
  • Overall assessment is that the prospect is good to create C offsets from biochar projects www.biocharprotocol.org
1. Avoided emissions that arise from changes in the management of feedstock that reduce CH4 or N2O emissions.
2. Carbon stabilised in biochar
3. Fossil fuel offsets from energy produced.
  • Much more difficult is to claim avoided emissions and C sequestration due to the benefits that arise where biochar is added to soil in agricultural settings. The mechanisms are clear but currently biochar specific evidence at the field scale is lacking (albeit increasing) further in general these areas are less well established in C markets.
  • It is also important to realise that a project will need to have its own data to support claims that they wish to make and that the costs of setting up a project, monitoring and verification can be significant. There is considerable scope for innovation in this area.
  • REDD+ can be a big help. Multi-species, managed forests. Management can double annual output and the most logical place for REDD+ output would seem to be Biochar.

Groups and networking

Biochar India Google Group http://groups.google.com/group/biocharindia/

Discussion format

This workshop aims to allow open discussion, covering controversies, risk and uncertainties surrounding biochar - if you have any suggestions for discussion topics, or any comments, please get in touch (sarah.carter @ ed.ac.uk)

What is biochar?

Biochar is the result of heating biomass (including wood and agricultural residues) in a zero to low oxygen environment to produce a charcoal type material, which can be used as a soil amendment. Once biochar is in the soil it can change the chemical and physical properties to potentially create more favourable conditions for crop growth. In addition it can provide a long-term carbon sink since it does not break down quickly in the soil. Thus, the carbon that might have gone in the atmosphere and caused global warming gets trapped in the soil by this process. Some researchers estimate that it will persist in the soil for 1000’s of years and will continue to provide benefits to the soil and crops. Biochar can be produced in a number of ways, from traditional charcoal kilns, to household cook stoves, to large scale gasification units operating for waste management or energy production.

Learn more about biochar here


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The workshop is organised by the Appropriate Rural Technology Institute (ARTI) and the UK Biochar Research Centre, University of Edinburgh.

ARTI is a renowned NGO in the field of biomass energy and sustainable agriculture. Two time winner of the prestigious Ashden Awards, ARTI is one of the pioneers in the area of R&D on biochar production and use in India (www.arti-india.org). The University of Edinburgh is one of the world’s top 20 universities and the UKBRC is an alliance that connects research organizations with significant research activity in the UK. The UKBRC aims to serve as a source of robust data and informed objective analysis on this subject to all stakeholders (www.biochar.org.uk).

Last edited by raffaella@ecoharmony.com .
Page last modified on Wednesday November 10, 2010 13:28:14 GMT.
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