Biochar

Biochar or terra preta, is a name for charcoal when it is used for particular purposes. Like all charcoal, biochar is created by pyrolysis of biomass. Biochar is under investigation as an approach to carbon sequestration via bio-energy with carbon capture and storage.[1] Biochar thus has the potential to help mitigate climate change, via carbon sequestration.[2] Independently, biochar can increase soil fertility, raise agricultural productivity and reduce pressure on forests, though the degree to which results offer long term carbon sequestration in practice has been challenged.[3] Biochar is a stable solid, rich in carbon and can endure in soil for thousands of years.[1]

Contents

History

Pre-Columbian Amazonians are believed to have used biochar to enhance soil productivity. They produced it by smoldering agricultural waste (i.e., covering burning biomass with soil)[4] in pits or trenches.[5] European settlers called it terra preta de Indio.[6] Following observations and experiments, a research team working in French Guiana hypothesized that the Amazonian earthworm Pontoscolex corethrurus was the main agent of fine powdering and incorporation of charcoal debris to the mineral soil.[7]

The term “biochar” was coined by Peter Read to describe charcoal used as a soil improvement.[8]

Production

Pyrolysis produces biochar, liquids and gases from biomass by heating the biomass in a low/no oxygen environment. The absence of oxygen prevents combustion. The relative yield of products from pyrolysis varies with temperature. Temperatures of 400–500 °C (752–932 °F) produce more char, while temperatures above 700 °C (1,292 °F) favor the yield of liquid and gas fuel components.[9] Pyrolysis occurs more quickly at the higher temperatures, typically requiring seconds instead of hours. High temperature pyrolysis is also known as gasification, and produces primarily syngas.[9] Typical yields are 60% bio-oil, 20% biochar, and 20% syngas. By comparison, slow pyrolysis can produce substantially more char (~50%). Once initialized, both processes produce net energy. For typical inputs, the energy required to run a “fast” pyrolyzer is approximately 15% of the energy that it outputs.[10] Modern pyrolysis plants can use the syngas created by the pyrolysis process and output 3–9 times the amount of energy required to run.[5]

The Amazonian pit/trench method[5] harvests neither bio-oil nor syngas, and releases a large amount of CO2, black carbon, and other greenhouse gases (GHG)s (and potentially, toxins) into the air. Commercial-scale systems process agricultural waste, paper byproducts, and even municipal waste and typically eliminate these side effects by capturing and using the liquid and gas products.

Centralized, decentralized and mobile systems

In a centralized system, all biomass in a region is brought to a central plant for processing. Alternatively, each farmer or group of farmers can operate a lower-tech kiln. Finally, a truck equipped with a pyrolyzer can move from place to place to pyrolyze biomass. Vehicle power comes from the syngas stream, while the biochar remains on the farm. The biofuel is sent to a refinery or storage site. Factors that influence the choice of system type include the cost of transportation of the liquid and solid byproducts, the amount of material to be processed, and the ability to feed directly into the power grid.

For crops that are not exclusively for biochar production, the residue-to-product ratio (RPR) and the collection factor (CF) the percent of the residue not used for other things, measure the approximate amount of feedstock that can be obtained for pyrolysis after harvesting the primary product. For instance, Brazil harvests approximately 460 million tons (MT) of sugarcane annually,[11] with an RPR of 0.30, and a CF of 0.70 for the sugarcane tops, which are normally burned in the field.[12] This translates into approximately 100 MT of residue annually which could be pyrolyzed to create energy and soil additives. Adding in the bagasse (sugarcane waste) (RPR=0.29 CF=1.0) which is otherwise burned (inefficiently) in boilers, raises the total to 230 MT of pyrolysis feedstock. Some plant residue, however, must remain on the soil to avoid increased costs and emissions from nitrogen fertilizers.[13]

Pyrolysis technologies for processing loose and leafy biomass produce both biochar and syngas.[14]

Thermo catalytic depolymerization

Alternatively, thermo-catalytic depolymerization using microwaves has recently been used to efficiently convert organic matter to biochar on an industrial scale, producing ~50% char.[15][16]

Uses

Carbon sink

See also: Geoengineering

The burning and natural decomposition of biomass and in particular agricultural waste adds large amounts of CO2 and CH4 to the atmosphere. Biochar can store large amounts of greenhouse gases in the ground, potentially reducing or stalling the growth 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.[17]

Biochar can sequester carbon in the soil for hundreds to thousands of years, like coal.[18][19][20] This technique is advocated by prominent scientists such as James Hansen, head of the NASA Goddard Institute for Space Studies,[21] and James Lovelock, creator of the Gaia hypothesis, for mitigation of global warming by greenhouse gas remediation.[22]

Biochar can sequester carbon in the soil for hundreds to thousands of years,[18][23][24][25] this storage property of carbon has received considerable interest as a potential tool to slow global warming. The IPCC Fourth Assessment Report includes Biochar as a key technology for reaching low carbon dioxide atmospheric concentration targets.[26] The negative emissions that can be produced by bio-energy with carbon capture and storage (BECCS) has been estimated by the Royal Society to be equivalent to a 50 to 150 ppm decrease in global atmospheric carbon dioxide concentrations.[2]

Annual net emissions of carbon dioxide (CO2), methane and nitrous oxide could be reduced by a maximum of 1.8 Pg CO2-C equivalent (CO2-C) per year (12% of current anthropogenic CO2-Ce emissions; 1 Pg=1 Gt), and total net emissions over the course of a century by 130 Pg CO2-Ce, without endangering food security, habitat or soil conservation.[27] According to the International Energy Agency, the BLUE map climate change mitigation scenario calls for more than 2 gigatons of negative CO2 emissions per year with BECCS in 2050.[28]

Biochar is a high-carbon, fine-grained residue which today is produced through modern pyrolysis processes. Pyrolysis is the direct thermal decomposition of biomass in the absence of oxygen to obtain an array of solid (biochar), liquid (bio-oil) and gas (syngas) products. The specific yield from the pyrolysis is dependent on process conditions, and can be optimized to produce either energy or biochar.[29] Even when optimized to produce char rather than energy, the energy produced per unit energy input is higher than for corn ethanol.[30]

Soil amendment

Biochar can be used as a soil amendment to improve yield, but only for plants that require high potash and elevated pH,[31] improve water quality, reduce soil emissions of greenhouse gases, reduce nutrient leaching, reduce soil acidity, and reduce irrigation and fertilizer requirements.[32]

These positive qualities are dependent on the properties of the biochar,[33] and may depend on regional conditions including soil type, soil condition (depleted or healthy), temperature, and humidity.[34] Modest additions of biochar to soil reduce nitrous oxide N2O emissions by up to 80% and eliminate methane emissions, which are both more potent greenhouse gases than CO2.[35]

Pollutants such as metals and pesticides seep into soil and contaminate food supplies, reducing the amount of land suitable for agricultural production. Studies have reported positive effects from biochar on crop production in degraded and nutrient–poor soils.[36] Biochar can be designed with specific qualities to target distinct properties of soils.[37] Biochar reduces leaching of critical nutrients, creates a higher crop uptake of nutrients, and provides greater soil availability of nutrients.[38] At 10% levels biochar reduced contaminant levels in plants by up to 80%, while reducing total chlordane and DDX content in the plants by 68 and 79%, respectively.[39]

Slash and char

Switching from slash and burn to slash and char techniques in Brazil can decrease both deforestation of the Amazon basin and carbon dioxide emission, as well as increase crop yields. Slash and burn leaves only 3% of the carbon from the organic material in the soil.[40]

Slash and char can sequester up to 50% of the carbon in a highly stable form.[41] Returning the biochar into the soil rather than removing it all for energy production reduces the need for nitrogen fertilizers, thereby reducing cost and emissions from fertilizer production and transport.[42] Additionally, by improving the soil tilth, fertility, and productivity, biochar – enhanced soils can indefinitely sustain agricultural production, whereas non-amended soils quickly become depleted of nutrients, forcing farmers to abandon the fields. This produces a continuous slash and burn cycle and the continued loss of tropical rainforest. Using pyrolysis to produce bio-energy also has the added benefit of not requiring infrastructure changes the way processing biomass for cellulosic ethanol does. Additionally, the biochar produced can be applied by the currently used tillage machinery or equipment used to apply fertilizer.[43]

Energy production: bio-oil & syngas

Bio-oil can be used as a replacement for numerous applications where fuel oil is used, including fueling space heaters, furnaces, and boilers.[44] Additionally, these biofuels can be used to fuel some combustion turbines and reciprocating engines, and as a source to create several chemicals.[44] If bio-oil is used without modification, care must be taken to prevent emissions of black carbon and other particulates. Syngas and bio-oil can also be “upgraded” to transportation fuels like biodiesel and gasoline substitutes.[45] If biochar is used for the production of energy rather than as a soil amendment, it can be directly substituted for any application that uses coal. pyrolysis also may be the most cost-effective way of producing electrical energy from biomaterial.[46] Syngas can be burned directly, used as a fuel for gas engines and gas turbines, converted to clean diesel fuel through the Fischer–Tropsch process or potentially used in the production of methanol and hydrogen.[47]

Bio-oil has a much higher energy density than the raw biomass material.[48] Mobile pyrolysis units can be used to lower the costs of transportation of the biomass itself if the biochar is returned to the soil and the syngas stream is used to power the process.[49][50] Bio-oil contains organic acids which are corrosive to steel containers, has a high water vapor content which is detrimental to ignition, and, unless carefully cleaned, contains some biochar particles which can block injectors.[51] The greatest potential for bio-oil seems to be its use in a bio-refinery, where compounds that are valuable chemicals, pesticides, pharmaceuticals or food additives are first extracted, and the remainder is either upgraded to fuel or reformed to syngas.[52]

Research

Further research is in progress, notably by Cornell University and the University of Georgia, which has a dedicated research unit.[53]

Students at Stevens Institute of Technology in New Jersey are developing supercapacitors that use electrodes made of biochar.[54] A process developed by University of Florida researchers which removes phosphate from water, also yields methane gas usable as fuel and phosphate-laden carbon suitable for enriching soil.[55]

Emerging commercial sector

Johannes Lehmann, of Cornell University, estimates that pyrolysis can be cost-effective for a combination of sequestration and energy production when the cost of a CO2 ton reaches $37.[56] As of mid-February 2010, CO2 is trading at $16.82/ton on the European Climate Exchange (ECX), so using pyrolysis for bioenergy production may be feasible even if it is more expensive than fossil fuels.

Pyrolysis does have costs associated with the machinery and heating (around US$4 per gigajoule) and is dependent on a supply of cheap biomass. At the local or field scale, biochar can usefully enhance existing sequestration approaches. It can be mixed with manures or fertilizers and included in no-tillage methods, without the need for additional equipment. Biochar has been shown to improve the structure and fertility of soils, thereby improving biomass production. Biochar not only enhances the retention and therefore efficiency of fertilizers but may, by the same mechanism, also decrease fertilizer run-off. For biochar sequestration to work on a much larger scale, an important factor is combining low-temperature pyrolysis with simultaneous capture of the exhaust gases and converting them to energy as heat, electricity, biofuel or hydrogen. Depending on the feedstock used and bioenergy produced, low-temperature pyrolysis with gas capture (but no sequestra- tion) can be a carbon-neutral energy source. Most companies that generate bioenergy in this way view biochar merely as a byproduct that can itself be burned to offset fossil-fuel use and reduce costs. But our calculations suggest that emissions reductions can be 12–84% greater if biochar is put back into the soil instead of being burned to offset fossil-fuel use. Biochar sequestration offers the chance to turn bioenergy into a carbon-negative industry.[57]

Current biochar projects are small scale and make no significant impact on the overall global carbon budget, although expansion of this technique has been advocated as a geoengineering approach.[58][59] The approach which favors applications that benefit the poorest is gaining traction: in May 2009, the Biochar Fund received a grant from the Congo Basin Forest Fund to implement its concept in Central Africa. In this concept, biochar is a tool used to simultaneously slow down deforestation, increase the food security of rural communities, provide renewable energy to them and sequester carbon.[60]

Various companies in North America, Australia and England sell biochar and/or biochar production units.

The 2009 International Biochar Conference in Boulder, Colorado saw the launch of a mobile pyrolysis unit with a specified intake of 1,000 pounds per hour (450 kg per hour). The unit, with a length of 12 feet and height of 7 feet (3.6 m by 2.1m), was intended for agricultural applications.[61]

A unit which opened in Dunlap, Tennessee in August 2009 after testing and an initial run, was subsequently shut down as part of a Ponzi scheme investigation.[62]

See also

Sustainable development portal
Ecology portal

Notes

  1. ^ a b Lean, Geoffrey (Sunday, 7 December 2008). "Ancient skills 'could reverse global warming'". The Independent. http://www.independent.co.uk/environment/climate-change/ancient-skills-could-reverse-global-warming-1055700.html. Retrieved October 1, 2011. 
  2. ^ a b "Geoengineering the climate: science, governance and uncertainty". The Royal Society. 2009. http://royalsociety.org/Geoengineering-the-climate/. Retrieved 2010-08-22. 
  3. ^ Report on Biochar trials in Cameroon by Biofuelwatch
  4. ^ Solomon, Dawit, Johannes Lehmann, Janice Thies, Thorsten Schafer, Biqing Liang, James Kinyangi, Eduardo Neves, James Petersen, Flavio Luizao, and Jan Skjemstad, Molecular signature and sources of biochemical recalcitrance of organic carbone in Amazonian Dark Earths, 71 Geochemica et cosmochemica ACTA 2285, 2286 (2007) (“Amazonian Dark Earths (ADE) are a unique type of soils apparently developed between 500 and 9000 years B.P. through intense anthropogenic activities such as biomass-burning and high-intensity nutrient depositions on pre-Columbian Amerindian settlements that transformed the original soils into Fimic Anthrosols throughout the Brazilian Amazon Basin.”) (internal citations omitted)
  5. ^ a b c Lehmann 2007a, pp. 381–387 To date, scientists have been unable to completely reproduce the beneficial growth properties of terra preta. It is hypothesized that part of the alleged benefits of terra preta require the biochar to be aged so that it increases the cation exchange capacity of the soil, among other possible effects. In fact, there is no evidence natives made biocahr for soil treatment, but really for transportable fuel charcoal. Abandoned or forgotten charcoal pits left for centuries were eventually reclaimed by the forest. In that time the harsh negative effects of the char (high pH, extreme ash content, salinity) had worn off and turned to positive as the forest soil ecosystem saturated the charcoals with nutrients. supra note 2 at 386 (“Only aged biochar shows high cation retention, as in Amazonian Dark Earths. At high temperatures (30–70°C), cation retention occurs within a few months. The production method that would attain high CEC in soil in cold climates is not currently known.”) (internal citations omitted).
  6. ^ Glaser, Lehmann & Zech 2002, pp. 219–220 “These so-called Terra Preta do Indio (Terra Preta) characterize the settlements of pre-Columbian Indios. In Terra Preta soils large amounts of black C indicate a high and prolonged input of carbonized organic matter probably due to the production of charcoal in hearths, whereas only low amounts of charcoal are added to soils as a result of forest fires and slash-and-burn techniques.”) (internal citations omitted)
  7. ^ Jean-François Ponge, Stéphanie Topoliantz, Sylvain Ballof, Jean-Pierre Rossi, Patrick Lavelle, Jean-Marie Betsch and Philippe Gaucher,Ingestion of charcoal by the Amazonian earthworm Pontoscolex corethrurus: a potential for tropical soil fertility, 38 Soil Biology & Biochemistry, 2008, 2009 (2006)
  8. ^ Read, Peter (27 March 2009). "This gift of nature is the best way to save us from climate catastrophe. Biochar schemes would remove carbon from the atmosphere and increase food supply, says Peter Read". Guardian (London). http://www.guardian.co.uk/commentisfree/2009/mar/27/biochar. 
  9. ^ a b Winsley, Peter (2007). "Biochar and bioenergy production for climate change mitigation". NEW ZEALAND SCI. REV. 5 64.  (See Table 1 for differences in output for Fast, Intermediate, Slow, and Gasification).
  10. ^ Laird 2008, pp. 100, 178–181 “The energy required to operate a fast pyrolyzer is ∼15% of the total energy that can be derived from the dry biomass. Modern systems are designed to use the syngas generated by the pyrolyzer to provide all the energy needs of the pyrolyzer.”
  11. ^ "Production Quantity Of Sugar Cane In Brazil In 2006". FAOSTAT. 2006. http://faostat.fao.org/site/567/DesktopDefault.aspx?PageID=567. Retrieved July 1, 2008. 
  12. ^ Perera, K.K.C.K., P.G. Rathnasiri, S.A.S. Senarath, A.G.T. Sugathapala, S.C. Bhattacharya, and P. Abdul Salam, Assessment of sustainable energy potential of non-plantation biomass resources in Sri Lanka, 29 Biomass & Bioenergy 199, 204 (2005) (showing RPRs for numerous plants, describing method for determining available agricultural waste for energy and char production).
  13. ^ Laird 2008, pp. 179 “Much of the current scientific debate on the harvesting of biomass for bioenergy is focused on how much can be harvested without doing too much damage.”
  14. ^ Jorapur, Rajeev; Rajvanshi, Anil K. (1997). "Sugarcane leaf-bagasse gasifier for industrial heating applications.". Biomass and Bioenergy 13 (3). doi:10.1016/S0961-9534(97)00014-7. >
  15. ^ Muto, Selhan; Bhaskar, Thallada (April 1, 2005). "Low-temperature catalytic hydrothermal treatment of wood biomass: analysis of liquid products,". Chemical Engineering Journal 108 (1-2): 127–137. ISSN 10.1016/j.cej.2005.01.007. 1385-8947, 10.1016/j.cej.2005.01.007.. http://www.sciencedirect.com/science/article/pii/S1385894705000227). Retrieved September 23, 2011. 
  16. ^ Jha, Alok (Friday 13 March 2009). "'Biochar' goes industrial with giant microwaves to lock carbon in charcoal". The Guardian. http://www.guardian.co.uk/environment/2009/mar/13/charcoal-carbon. Retrieved September 23, 2011. 
  17. ^ Laird 2008, pp. 100, 178–181
  18. ^ a b Lehmann, Johannes. "Terra Preta de Indio". Soil Biochemistry (internal citations omitted). http://www.css.cornell.edu/faculty/lehmann/research/terra%20preta/terrapretamain.html.  Not only do biochar-enriched soils contain more carbon - 150gC/kg compared to 20-30gC/kg in surrounding soils - but biochar-enriched soils are, on average, more than twice as deep as surrounding soils.
  19. ^ Lehmann 2007b “this sequestration can be taken a step further by heating the plant biomass without oxygen (a process known as low-temperature pyrolysis).”
  20. ^ Lehmann 2007a, pp. 381, 385 “pyrolysis produces 3–9 times more energy than is invested in generating the energy. At the same time, about half of the carbon can be sequestered in soil. Such a carbon-negative technology would lead to a net withdrawal of CO2 from the atmosphere, while producing and consuming energy.”
  21. ^ Hamilton, Tyler (22 June 2009). "Sole option is to adapt, climate author says". The Star (Toronto). http://www.thestar.com/sciencetech/article/654444. 
  22. ^ Vince 2009
  23. ^ Vince 2009 Therefore, the total carbon stored in these soils can be one order of magnitude higher than adjacent soils.
  24. ^ Winsley, Peter (2007). "Biochar and Bioenergy Production for Climate Change Mitigation". New Zealand Sci. Review. 64 (5): 5. http://www.biochar-international.org/images/NZSR64_1_Winsley.pdf. 
  25. ^ Kern, Dirse C. (July 9–15, 2006). "New Dark Earth Experiment in the Tailandia City – Para-Brazil: The Dream of Wim Sombroek". 18th World Congress of Soil Science. 
  26. ^ Fischer, B.S., N. Nakicenovic, K. Alfsen, J. Corfee Morlot, F. de la Chesnaye, J.-Ch. Hourcade, K. Jiang, M. Kainuma, E. La Rovere, A. Matysek, A. Rana, K. Riahi, R. Richels, S. Rose, D. van Vuuren, R. Warren, (2007)“Issues related to mitigation in the long term context”, In Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Inter-governmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], Cambridge University Press, Cambridge.
  27. ^ "Sustainable biochar to mitigate global climate change". Nature Communications. 2010. http://www.nature.com/ncomms/journal/v1/n5/full/ncomms1053.html. 
  28. ^ "IEA Technology Roadmap Carbon Capture and Storage 2009". OECD/IEA. 2009. https://www.iea.org/papers/2009/CCS_Roadmap.pdf. Retrieved 2010-10-22. 
  29. ^ Gaunt & Lehmann 2008, pp. 4152, 4155 (“Assuming that the energy in syngas is converted to electricity with an efficiency of 35%, the recovery in the life cycle energy balance ranges from 92 to 274 kg CO2 MW-1 of electricity generated where the pyrolysis process is optimized for energy and 120 to 360 kilograms (790 lb) CO2MW-1 where biochar is applied to land. This compares to emissions of 600–900 kilograms (1,300–2,000 lb) CO2MW-1 for fossil-fuel-based technologies.)
  30. ^ Gaunt & Lehmann 2008, pp. 4152 (“Despite a reduction in energy output of approximately 30% where the slow pyrolysis technology is optimized to produce biochar for land application, the energy produced per unit energy input at 2–7 MJ/MJ is greater than that of comparable technologies such as ethanol from corn.”)
  31. ^ Lehmann, Johannes, and Jose Pereira da Silva Jr., Christoph Steiner, Thomas Nehls, Wolfgang Zech, & Bruno Glaser, Nutrient availability and leaching in an archaeological Anthrosol and a Ferralsol of the Central Amazon basin: fertilizer, manure and charcoal amendments, 249 Plant & Soil 343, 355 (2003)
  32. ^ Supra note 6; Day, Danny, Robert J. Evans, James W. Lee, and Don Reicosky, Economical CO2, SOx, and NOx capture from fossil-fuel utilization with combined renewable hydrogen production and large-scale carbon sequestration, 30 Energy 2558, 2560
  33. ^ Glaser, Lehmann & Zech 2002, pp. 224 note 7 “Three main factors influence the properties of charcoal: (1) the type of organic matter used for charring, (2) the charring environment (e.g. temperature, air), and (3) additions during the charring process. The source of charcoal material strongly influences the direct effects of charcoal amendments on nutrient contents and availability.”
  34. ^ Dr. Wardle points out that plant growth has been observed in tropical (depleted) soils by referencing Lehmann, but that in the boreal (high native soil organic matter content) forest this experiment was run in, it accelerated the native soil organic matter loss. Wardle, supra note 18. (“Although several studies have recognized the potential of black C for enhancing ecosystem carbone sequestration, our results show that these effects can be partially offset by its capacity to stimulate loss of native soil C, at least for boreal forests.”) (internal citations omitted) (emphasis added).
  35. ^ Lehmann 2007a, pp. note 3 at 384 “In greenhouse experiments, NOx emissions were reduced by 80% and methane emissions were completely suppressed with biochar additions of 20 g kg-1 (2%) to a forage grass stand.”
  36. ^ http://www.csiro.au/resources/Biochar-Factsheet.html
  37. ^ Novak, Jeff. Development of Designer Biochar to Remediate Specific Chemical and Physical Aspects of Degraded Soils. Proc. of North American Biochar Conference 2009, University of Colorado at Boulder. Florence: U.S. Department of Agriculture, 2009. 1-16. Print
  38. ^ Julie, Major, Johannes Lehmann, Macro Rondon, and Susan J. Riha. Nutrient Leaching below the Rooting Zone Is Reduced by Biochar, the Hydrology of a Columbian Savanna Oxisol Is Unaffected. Proc. of North American Biochar Conference 2009, University of Colorado at Boulder. Ithaca: Cornell University Department of Crop and Soil Sciences, 2009. Print.
  39. ^ Elmer, Wade, Jason C. White, and Joseph J. Pignatello. Impact of Biochar Addition to Soil on the Bioavailability of Chemicals Important in Agriculture. Rep. New Haven: University of Connecticut, 2009. Print.
  40. ^ Glaser, Lehmann & Zech 2002, pp. note 7 at 225 “The published data average at about 3% charcoal formation of the original biomass C.”
  41. ^ Biochar Sequestration In Terrestrial Ecosystems – A Review, by Johannes Lehmann, John Gaunt, and Marco Rondon. Mitigation and Adaptation Strategies for Global change 403, 404 (2006). supra note 11 at 407 (“If this woody aboveground biomass were converted into biochar by means of simple kiln techniques and applied to soil, more than 50% of this carbon would be sequestered in a highly stable form.”)
  42. ^ Gaunt & Lehmann 2008, pp. 4152 note 3 (“This results in increased crop yields in low-input agriculture and increased crop yield per unit of fertilizer applied (fertilizer efficiency) in high-input agriculture as well as reductions in off-site effects such as runoff, erosion, and gaseous losses.”)
  43. ^ Lehmann 2007b, pp. note 9 at 143 “It can be mixed with manures or fertilizers and included in no-tillage methods, without the need for additional equipment.”
  44. ^ a b Badger & Fransham 2006, pp. 321&ndash322 (“including fueling space heaters, furnaces, and boilers (includingcofiring in utility boilers); and fueling certain combustion turbines and reciprocating engines, as well as serving as a source of several chemicals.”)
  45. ^ Laird 2008, pp. note 21 at 178
  46. ^ Bridgwater, A. V., A.J. Toft, and J.G. Brammer, A techno-economic comparison of power production by biomass fast pyrolysis with gasification and combustion, 6 Renewable & Sustainable Energy Rev. 181, 231 (“the fast pyrolysis and diesel engine system is clearly the most economic of the novel systems at scales up to 15 MWe”);
  47. ^ McKendry, Peter, Energy production from biomass (part 2): conversion technologies, 83 BIORESOURCE TECH. 47, 48-49 (2002) (“can be burnt directly or used as a fuel for gas engines and gas turbines. . . . The production of syngas from biomass allows the production of methanol and hydrogen.”) (internal citations omitted).
  48. ^ Badger & Fransham 2006, pp. note 36 at 323
  49. ^ Badger & Fransham 2006, pp. 322
  50. ^ Michael Jacobson, Cedric Briens and Franco Berruti, “Lift tube technology for increasing heat transfer in an annular pyrolysis reactor”, CFB’9, Hamburg, Germany, May 13–16, 2008.
  51. ^ Yaman, Serdar, pyrolysis of biomass to produce fuels and chemical feedstocks, 45 Energy Conversion & MGMT 651, 659 (2003).
  52. ^ Cedric Briens, Jan Piskorz and Franco Berruti, Biomass Valorization for Fuel and Chemicals Production -- A Review, 2008. International Journal of Chemical Reactor Engineering, 6, R2.
  53. ^ "Can Biochar save the planet?". University of Edinburgh. http://www.cnn.com/video/#/video/tech/2009/03/30/ansari.biochar.cnn. Retrieved 2009-03-10. 
  54. ^ "A Cheaper, Greener Material for Supercapacitors". Stevens Institute of Technology. 2011. http://www.solarnovus.com/index.php?option=com_content&view=article&id=2859:a-cheaper-greener-material-for-supercapacitors&catid=52:applications-tech-research&Itemid=247. Retrieved 2011-05-25. 
  55. ^ "Biochar" More Effective, Cheaper at Removing Phosphate from Water". University of Florida. 2011. http://eponline.com/articles/2011/05/18/biochar-more-effective-cheaper-at-removing-phosphate-from-water.aspx. Retrieved 2011-05-18. 
  56. ^ Lehmann 2007b, pp. 143, 144 “We calculate that biochar sequestration in conjunction with bioenergy from pyrolysis becomes economically attractive, under one specific scenario, when the value of avoided carbon dioxide emissions reaches $37 per tonne.”
  57. ^ Lehmann 2007b, pp. 143, 144 “Pyrolysis does have costs associated with the machinery and heating (around US$4 per gigajoule) and is dependent on a supply of cheap biomass. But the bigger question is whether this approach can be scaled up to national and regional, or even global, scales. At the local or field scale, bio- char can usefully enhance exist- ing sequestration approaches. It can be mixed with manures or fertilizers and included in no-tillage methods, without the need for addi- tional equipment. Biochar has been shown to improve the structure and fertility of soils, thereby improving biomass production3. Biochar not only enhances the retention6 and therefore efficiency of fertilizers but may, by the same mechanism, also decrease fertilizer run-off. For biochar sequestration to work on a much larger scale, an important factor is combining low-temperature pyrolysis with simultaneous capture of the exhaust gases and converting them to energy as heat, electricity, biofuel or hydrogen3. Depending on the feedstock used and bioenergy produced, low-temperature pyrolysis with gas capture (but no sequestra- tion) can be a carbon-neutral energy source. Most companies that generate bioenergy in this way view biochar merely as a byproduct that can itself be burned to offset fossil-fuel use and reduce costs. But our calculations suggest that emissions reductions can be 12–84% greater if biochar is put back into the soil instead of being burned to offset fossil-fuel use7. Biochar sequestration offers the chance to turn bioen- ergy into a carbon-negative industry.”
  58. ^ Ananthaswamy, Anil, Microwave factory to act as carbon sink, NEW SCIENTIST, 1 October (2008) (“Retrieved on 12 December 2008)
  59. ^ Biochar: Is the hype justified? By Roger Harrabin - Environment analyst, (09:20 GMT, Monday, 16 March 2009) BBC News
  60. ^ Biochar project wins critical funding for protection of rainforests in Congo
  61. ^ Austin, Anna (2009-10). "A New Climate Change Mitigation Tool". Biomass Magazine (BBI International). http://www.biomassmagazine.com/article.jsp?article_id=3091&q=&page=all. Retrieved 2009-10-30. 
  62. ^ Blumenthal, Jeff (17 November 2009). "Wragg, Knorr ordered to halt Mantria operations". Philadelphia Business Journal. http://philadelphia.bizjournals.com/philadelphia/stories/2009/11/16/daily25.html. 

References

External links

Biochar organisations by country

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