Biochar

Biochar is a charcoal produced from biomass that can store carbon. It is of increasing interest because of concerns about global warming caused by emissions of CO2 and other greenhouse gases. In some cases, the term is used specifically to mean biomass charcoal produced via pyrolysis. Biochar may be an immediate solution to reducing the global impact of farming (and in reducing the impact from all agricultural waste). The burning and decomposition of trees and agricultural matter contributes a large amount of CO₂ to the atmosphere. Biochar can store this CO₂ in the ground and the presence of the biochar in the earth increases soil productivity, which will allow farmers to stop encroaching on rainforests as a source of more fertile farmland.

As a result of significant product variations due to varying technology, process conditions, and feedstock compositions, biochar cannot be considered a commodity product. Biochar is sold under a range of brand names such as Agrichar™ which relates to Biochar produced from the BEST Energies proprietary slow pyrolysis process.

Current biochar projects are small scale and make no significant impact on the overall global carbon budget.

Carbon sink potential and soil co-benefits

Biochar can sequester carbon in the soil for hundreds to thousands of years [ [http://www.css.cornell.edu/faculty/lehmann/terra_preta/TerraPretahome.htm "Terra Preta de Indio"] , Lehmann, Johannes, in Soil Biochemistry (internal citations omitted); "see also" [http://www.biochar-international.org/images/NZSR64_1_Winsley.pdf "Biochar and Bioenergy Production for Climate Change Mitigation"] , Winsley, Peter, 64 New Zealand Sci. Review. 5, 5 (2007); Kern, Dirse C.,"New Dark Earth Experiment in the Tailandia City – Para-Brazil: The Dream of Wim Sombroek", 18th World Congress of Soil Science (9-15 July 2006). 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. Therefore, the total carbon stored in these soils can be one order of magnitude higher than adjacent soils. "See id"] . Pre-Columbian Amazonian Indians used it to enhance soil productivity and made it by smoldering agricultural waste [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)] . They called it "Terra Preta de Indio". [Glaser, Bruno, Johannes Lehmann, and Wolfgang Zech," Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal – a review", 35 Biology and Fertility Soils 219, 220 (2002) (“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)] Its modern equivalent is being developed using pyrolysis to heat biomass in the absence of oxygen in kilns [Lehmann, Johannes, "A handful of carbon", 447 Nature 143, 143 (2007) (“this sequestration can be taken a step further by heating the plant biomass without oxygen (a process known as low-temperature pyrolysis).”)] .

Modern biochar production can be combined with biofuel production in a process that is energy-positive(exothermic)—producing 3-9 times more energy than invested, is carbon-negative—withdrawing CO₂ from the atmosphere and rebuilds geological carbon sinks [Lehmann, Johannes, "Bio-energy in the black," 5 Front Ecol Environ 381, 385 (2007) (“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.”)] .

Biochar is a high-carbon, fine-grained residue which can be produced either by smoldering biomass utilizing centuries-old techniques (i.e., covering burning biomass with soil and letting it smolder) or 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 [Gaunt, John L. and Johannes Lehmann, "Energy Balance and Emissions Associated with Biochar Sequestration and Pyrolysis Bioenergy Production", 42 Environmental Sciences & Technologies. 4152, 4155 (2008) (“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 kg CO₂ MW-1 where biochar is applied to land. This compares to emissions of 600–900 kgCO₂MW-1 for fossil-fuel-based technologies.)] . Even when optimized to produce char rather than energy, the energy produced per unit energy input is higher than for corn ethanol ["Id." at 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.”)] .

In addition to its potential for carbon sequestration, biochar has numerous co-benefits when added to soil. It can prevent the leaching of nutrients out of the soil, [Steiner, Christoph, Wenceslau G. Teixeira, Johannes Lehmann, Thomas Nehls, Jeferson Luis, Vasconcelos de Macêdo, Winfried E. H. Blum, Wolfgang Zech, "Long term effects of manure, charcoal and mineral fertilization on crop production and fertility on a highly weathered Central Amazonian upland soil", 291 Plant & Soil 275, 287 (“The application of charcoal significantly reduced leaching of applied mineral fertilizer N. The increased ratio of uptake to leaching due to charcoal application indicates a high efficiency of nutrients applied with charcoal.”)] increase the available nutrients for plant growth, ["Id." (“The increased ratio of uptake to leaching due to charcoal application indicates a high efficiency of nutrients applied with charcoal. In this study, we were not able to statistically prove increased availability of soil nutrient contents but in spite of significantly higher nutrient export by means of yield withdrawal, the available nutrient contents remained as high or higher in soils receiving charcoal than only mineral fertilized soils (Fig. 4).”)] increase water retention, [Glaser, Bruno, Johannes Lehmann, and Wolfgang Zech, "Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal – a review", 35 Biology and Fertility Soils 219, 223 (2002) (“ [S] oil water retention increased by 18% upon addition of 45% (by volume) charcoal to a sandy soil. Glaser et al. (2002b) reported that charcoal-rich Anthrosols whose surface areas were 3 times higher than those of surrounding soils increased the field capacity by 18%. Tryon (1948) also studied the effect of charcoal on the percentage of available moisture in soils of different textures. Only in sandy soil did the addition of charcoal increase the available moisture (Table 3). In loamy soil, no changes were observed, and in clayey soil the available soil moisture even decreased with increasing coal additions, probably due to hydrophobicity of the charcoal. Therefore, improvements of soil water retention by charcoal additions may only be expected in coarse-textured soils or soils with large amounts of macropores”) (internal citations omitted) ("citing" Tryon, EH, Effect of charcoal on certain physical, chemical, and biological properties of forest soils, 18 Ecological Monographs 81 1948)).] and reduce the amount of fertilizer required. Additionally, it has been shown to decrease N₂0 (Nitrous oxide) and CH₄ (methane) emissions from soil, thus further reducing GHG (greenhouse gases) emissions. [Gaunt, "supra" note 3 at 4152. (“Rondon et al. found that CH4 emissions were completely suppressed and N2O emissions were reduced by 50% when biochar was applied to soil. Yanai et al. also found suppression of N₂0 when biochar was added to soil”) (internal citations omitted).] Biochar can be utilized in many applications as a replacement for or co-terminous strategy with other bioenergy production strategies. One of its most immediate uses is in switching from "slash-and-burn” to “slash-and-char” to prevent the rapid deforestation and subsequent degradation of soils.

“Biochar sequestration does not require a fundamental scientific advance and the underlying production technology is robust and simple, making it appropriate for many regions of the world.” [Lehmann, Johannes,"A handful of carbon", 447 Nature 143, 144 (2007).] Johannes Lehmann, of Cornell University, estimates that pyrolysis will be cost feasible when the cost of a CO₂ ton reaches $37, ["Id". (“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.”)] (as of the end of June 2008, CO₂ is trading at $45/ton on the [https://www.theice.com/marketdata/emissionsView/emissionsIndexView.jsp ECX] ) – so using pyrolysis for bioenergy production is feasible, even though it may be more expensive than fossil fuels at the moment.

Pyrolysis of biomass as a carbon sink

Biochar can be used to sequester carbon on centurial or even millennial time scales. Plant matter absorbs CO₂ from the atmosphere while growing. In the natural carbon cycle, plant matter decomposes rapidly after the plant dies, which emits CO₂; the overall natural cycle is carbon neutral. Instead of allowing the plant matter to decompose, pyrolysis can be used to sequester the carbon in a much more stable form. Biochar thus removes circulating CO₂ from the atmosphere and stores it in virtually permanent soil carbon pools, making it a carbon-negative process. In places like the Rocky Mountains, where beetles have been killing off vast swathes of pine trees, the utilization of pyrolysis to char the trees instead of letting them decompose into the atmosphere would offset substantial amounts of CO₂ emissions. Although some organic matter is necessary for agricultural soil to maintain its productivity, much of the agricultural waste can be turned directly into biochar, bio-oil, and syngas. [The question scientists are debating is precisely how much can be removed. Adding the char back into the soil makes up for a large amount of the SOM (soil organic matter) needed, but it may not be sufficient in all cases.] The use of pyrolysis also provides an opportunity for the processing of municipal waste into useful clean energy rather than increased problems with land space for storage. [Shinogi, Y., H. Yoshida, T. Koizumi, M. Yamaoka, and T. Saito, "Basic characteristics of low-temperature carbon products from waste sludge", 7 Advances Envtl. RES. 661, (2003) (“The results showed there are not harmful levels (based on the Japanese standard) of heavy metals and harmful substances.”), See also [http://www.hnei.hawaii.edu/bio.r3.asp#flashcarb Flash Carbonization] , M. Antal, Hawaii Natural Energy Institute (1 July 2008).]

Biochar is believed to have long mean residence times in the soil. While the methods by which biochar mineralizes (turns into CO₂) are not completely known, [Masiello, C.A., "New directions in black carbon organic geochemistry", 92 Marine Chemistry 201, 202 (2004) (“We know little about black carbon (biochar) loss processes and almost nothing about biotic or abiotic agents of black carbon decomposition.”)] evidence from soil samples in the Amazon shows large concentrations of black carbon (biochar) remaining after they were abandoned thousands of years ago. [ Lehmann, Johannes, John Gaunt, and Marco Rondon, "Biochar Sequestration In Terrestrial Ecosystems – A Review", "supra" note 11 Mitigation and Adaptation Strategies for Globl chnge 403, 404 (2006) (“Large amounts of biochar-derived carbone stocks remain in these soils today, hundreds and thousands of years after they were abandoned. The total carbone storage is as high as 250MgCha−1 m−1 compared to typical values of 100MgCha−1 m−1 in Amazonian soils derived from similar parent material.”) (internal citations omitted).] The amount of time the biochar will remain in the soil depends on the feedstock material, how charred the material is, the surface:volume ratio of the particles, and the conditions of the soil the biochar is placed in. [Cheng, Chih-Hsin, Johannes Lehmann, and Mark H. Engelhard, "Natural oxidation of black carbon in soils: Changes in molecular form and surface charge along a climosequence", 72 Geochemica et Cosmochemica ACTA 1598, 1599 (2008) (“Biotic and abiotic processes, such as greater temperature and moisture, may facilitate black carbon oxidation, while aggregate protection of black carbon [decreased surface to volume ratio] promoted in fine-textured soils may reduce black carbon oxidation.”); "see also infra" note 17.] Estimates for the residence time range from 100 to 10,000 yrs, with 5,000 being a common estimate. [Cheng, Chih-Hsin, Johannes Lehmann, Janice E. Thies, and Sarah D. Burton, "Stability of black carbon in soils across a climatic gradient", 113 J. Geophysical Res. G02027, 8 (2008) (“the half-life of black carbon at a site with 10C MAT may be as high as 925 years. Due to systematic overestimation of long-term black carbon decay by short-term incubations, the true half-life of black carbon is most likely greater than calculated here. This agrees well with the C-14 ages of black carbon which have been reported to lie in the hundreds to thousands of years”) (emphasis added) (internal citations omitted); Warnock, Daniel D. & Johannes Lehmann, "Mycorrhizal responses to biochar in soil – concepts and mechanisms", 300 Plant & Soil 9 (2007) (“Biochar is believed to have long mean residence times in soil, ranging from 1,000 to 10,000 years, with 5,000 years being a common estimate.”)] Lab experiments confirm a decrease in carbon mineralization with increasing temperature, so carefully controlled charring of plant matter can increase the soil residence time of the biochar C. [Baldock and Smernik (2002) used red pine (Pinus resinosa) wood charred at different temperatures. After 120 days incubation in sand, 20% of carbone was mineralized from wood heated at 70 carbone (essentially unaltered). Carbon mineralization decreased to 13% for wood heated to 150 C, and to less than 2% for chars produced at 200–350 C, with increasing proportions of aromatic C.] Under some circumstances, the addition of biochar to the soil has been found to accelerate the mineralization of the existing soil organic matter, [Wardle, David, Marie-Charlotte Nilsson, and Olle Zackrisson, "Fire-Derived Charcoal Causes Loss of Forest Humus", 320 Science 1 (2 May 2008) (“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.”) (emphasis added) (internal citations omitted).] but this would only reduce and not suppress the net benefit gained by sequestering carbon in the soil by this method. Furthermore, the suggested soil conditions for the integration of biochar are in heavily degraded tropical soils used for agriculture, not organic matter-rich boreal forest soils (as tested in the above reference).

Production of biochar

The yield of products from pyrolysis varies heavily with temperature. The lower the temperature, the more char is created per unit biomass. [Winsley, Peter, "Biochar and bioenergy production for climate change mitigation", 64 NEW ZEALAND SCI. REV. 5 (2007) (See Table 1 for differences in output for Fast, Intermediate, Slow, and Gasification).] High temperature pyrolysis is also known as gasification, and produces primarily syngas from the biomass. ["Id."] The two main methods of pyrolysis are “fast” pyrolysis and “slow” pyrolysis. Fast pyrolysis yields 60% bio-oil, 20% biochar, and 20% syngas, and can be done in seconds, whereas slow pyrolysis can be optimized to produce substantially more char (~50%), but takes on the order of hours to complete. For typical inputs, the energy required to run a “fast” pyrolyzer is approximately 15% of the energy that it outputs. [Laird, David A., "The Charcoal Vision: A Win–Win–Win Scenario for Simultaneously Producing Bioenergy, Permanently Sequestering Carbon, while Improving Soil and Water Quality", 100 AGRONOMY J. 178, 179 (2008) (“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.”)] Modern pyrolysis plants can be run entirely off of the syngas created by the pyrolysis process and thus output 3-9 times the amount of energy required to run. [Lehmann - Bioenergy in the Black," supra" note 3.]

The ancient method for producing biochar as a soil additive was the “pit” or “trench” method, which created terra preta, or dark soil. [To date, scientists have been unable to completely reproduce the beneficial growth properties of "terra preta". It is hypothesized that part of the benefit of "terra preta" may require the biochar to be aged so that it increases the cation exchange capacity of the soil. Lehmann, Bio-energy in the black, "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).] While this method is still a potential to produce biochar in rural areas, it does not allow the harvest of either the bio-oil or syngas, and releases a large amount of CO₂, black carbon, and other GHGs (and potentially, toxins) into the air. Modern companies are producing commercial-scale systems to process agricultural waste, paper byproducts, and even municipal waste.

There are three primary methods for deploying a pyrolysis system. The first is a centralized system where all biomass in the region would be brought to a pyrolysis plant for processing. A second system would effectively mean a lower-tech pyrolysis kiln for each farmer or small group of farmers. A third system is a mobile system where a truck equipped with a pyrolyzer would be driven around to pyrolyze biomass. It would be powered using the syngas stream, return the biochar to the earth, and transport the bio-oil to a refinery or storage site. Whether a centralized system, a distributed system, or a mobile system is preferred is heavily dependent on the specific region. The cost of transportation of the liquid and solid byproducts, the amount of material to be processed in a region, and the ability to feed directly into the power grid are all factors to be considered when deciding on a specific implementation.

Unless crops are going to be dedicated to biochar production, the residue-to-product ratio (RPR) for the feedstock material is a useful gauge of the approximate amount of feedstock that can be obtained for pyrolysis after the primary product is harvested and the waste remains. The amount of crop residue available to be used for pyrolysis can be determined by using the RPR, and the collection factor (the percent of the residue not used for other things). For instance, Brazil harvests approximately 460Mt of sugar cane annually [ FAOSTAT 2006, "available at" http://faostat.fao.org/site/567/DesktopDefault.aspx?PageID=567 (accessed 1 July 2008) (production quantity of sugar cane in brazil in 2006).] , with an RPR of 0.30, and a collection factor (CF) of 0.70 for the sugar cane tops, which are normally burned on the field. [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).] This translates into approximately 100Mt of residue which can be pyrolyzed to create energy and soil additives annually. Adding in the bagasse (sugar cane waste) (RPR=0.29 CF=1.0) which is currently burned inefficiently in boilers, raises the total to 230 Mt of pyrolysis feedstock just from sugar cane residues. Some plant residue, however, must remain on the soil to avoid heavily increased costs and emissions from nitrogen fertilizers. [Laird, "supra" note 21 at 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.”)]

Co-benefits of pyrolysis

Biochar can be used as a soil amendment to increase plant growth yield, [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) (“The amounts of charcoal added were clearly critical for the effects on crop growth and nutrition. Already at charcoal additions of 10% (w/w) plant growth improved significantly and larger quantities added further increased biomass production.”)] improve water quality, reduce soil emissions of GHGs, reduce leaching of nutrients, reduce soil acidity, and reduce irrigation and fertilizer requirements. ["Supra" note 6; Day, Danny, Robert J. Evans, James W. Lee, and Don Reicosky, "Economical CO₂, SO_x, and NO_x capture from fossil-fuel utilization with combined renewable hydrogen production and large-scale carbon sequestration", 30 Energy 2558, 2560 (“char also provides the ability to capture farm chemical runoff.”); Winsley, "supra" note 18 at 6. (“The carbon in biochar . . . improves soil structure and water retention, enhances nutrient availability, lowers acidity, and reduces the toxicity of aluminium to plant roots and soil microbiota. Biochar may help reduce the bioavailability of heavy metals and endocrine disruptors in some production systems and may therefore have potential in bioremediation.”)] These properties are very dependent on the properties of the biochar, [Glaser, "supra" note 7 at 224 (“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.”)] and may depend on regional conditions including soil type, condition (depleted or healthy), temperature, and humidity. [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).] Modest additions of biochar to soil were found to reduce N2O emissions by up to 80% and completely suppress methane emissions. [Lehmann - Bioenergy in the Black, "supra" 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 to a forage grass stand.”)]

Switching from slash-and-burn to slash-and-char techniques in Brazil can both decrease deforestation of the Amazon and increase the crop yield. Under the current method of slash-and-burn, only 3% of the carbon from the organic material is left in the soil. [Glaser, "supra" note 7 at 225 (“The published data average at about 3% charcoal formation of the original biomass C.”)]

Switching to slash-and-char can sequester up to 50% of the carbon in a highly stable form. ["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 carbone would be sequestered in a highly stable form.”)] Adding the biochar back into the soil rather than removing it all for energy production is necessary to avoid heavy increases in the cost and emissions from more required nitrogen fertilizers. [Gaunt, "supra" note 3 at 4152 (“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.”)] Additionally, by improving the soil tilth, fertility, and productivity, the biochar enhanced soils can sustain agricultural production, whereas non-amended soils quickly become depleted of nutrients, and the fields are abandoned, leading to 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. [Lehmann, "A handful of carbon", "supra" note 9 at 143. (“It can be mixed with manures or fertilizers and included in no-tillage methods, without the need for additional equipment.”)]

Pyrolysis for the production of energy

Bio-oil can be used as a replacement for numerous applications where fuel oil is used, including fueling space heaters, furnaces, and boilers. [Badger, Phillip C. and Peter Fransham, "Use of mobile fast pyrolysis plants to densify biomass and reduce biomass handling costs—A preliminary assessment", 30 Biomass & Bioenergy 321, 322 (2006) (“including fueling space heaters, furnaces, and boilers (including cofiring in utility boilers); and fueling certain combustion turbines and reciprocating engines, as well as serving as a source of several chemicals.”)] Additionally, these biofuels can be used to fuel some combustion turbines and reciprocating engines, and as a source to create several chemicals. ["Id."] 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. [Laird, "supra" note 21 at 178.] 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. [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”); ] Syngas can be burned directly, used as a fuel for gas engines and gas turbines, or potentially used in the production of methanol and hydrogen. [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).]

Bio-oil has a much higher energy density than the raw biomass material. [Badger, "supra" note 36 at 323.] 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. ["Id." at 322] Bio-oil contains organic acids which are corrosive to steel containers, has a high water vapor content which is detrimental to ignition, and contains some biochar in the liquid which can block injectors. [Yaman, Serdar, "Pyrolysis of biomass to produce fuels and chemical feedstocks", 45 Energy Conversion & MGMT 651, 659 (2003).]

ee also

*Black carbon
*Terra preta

References

External links

* Institute for Governance & Sustainable Development, http://www.igsd.org; International Network for Environmental Compliance & Enforcement, http://www.inece.org.
* International Biochar Initiative, http://www.biochar-international.org/home.html
*cite web | title= Carbon-negative primary production: Role of biocarbon and challenges for organics in Aotearoa/New Zealand | url= http://www.organic-systems.org/journal/Vol%202(2)/pdf/02-13%20HARRIS-HILL%202nd%20Hill%20edit%20accptd%2007b.pdf |format= PDF
*cite web | title= Biochar Research at Cornell University| url=http://www.css.cornell.edu/faculty/lehmann/biochar/Biochar_home.htm
*cite web | title= International Agrichar Initiative 2007 Conference | url=http://power.networksolutions.com/index.html
*cite web | title= Eprida Home Page | url= http://www.eprida.com | accessdate=2006-05-08
*cite web | title= Best Energies | url= http://www.bestenergies.com/ | accessdate=2008-07-10
*cite web | title= Biochar Fund | url=http://www.biocharfund.com/
*cite web | title= Terra Preta | work = Hypography discussion forum | url=http://hypography.com/forums/terra-preta/3451-terra-preta-parent-thread-started-all.html | accessdate=2006-05-08
*cite web | title=Putting the carbon back: Black is the new green | work=Nature| url = http://www.nature.com/nature/journal/v442/n7103/full/442624a.html | accessdate=2008-07-10
*cite web | title=Enhancing soil productivity with char | work=AG Professional| url = http://www.dynamotive.com/assets/articles/2007/2007.08%20AG%20Professional.pdf |format= PDF | accessdate=2008-01-11
*cite web | title=Pyrolysis char rejunevates tired soils | work=Biomass Magazine| url = http://www.biomassmagazine.com/article.jsp?article_id=1298&q=Dynamotive | accessdate=2008-01-11
*cite web | title=A handful of carbon | work=Nature| url = http://www.nature.com/nature/journal/v447/n7141/full/447143a.html | accessdate=2008-01-11
*cite web | title= Terra Preta Discussion List| url=http://terrapreta.bioenergylists.org/ | accessdate=2008-07-10
*cite web | title= The Biochar Page| url=http://www.biochar.org
*cite web |url=http://www.sciam.com/article.cfm?id=pyrolyisis-terra-preta-could-eliminate-garbage-generate-oil-carbon-sequestration |title= "Special Report: Inspired by Ancient Amazonians, a Plan to Convert Trash into Environmental Treasure" |accessdate=2007-05-30 |first=Anne |last=Casselman |year=2007 |month=May |format= |work=Scientific American |publisher= |pages= |quote=
*cite web |url=http://orgprints.org/13268/01/Biochar_as_a_soil_amendment_-_a_review.pdf |title= Biochar as a Soil Amendment - A review of the Environmental Implications |accessdate=2008-04-15 |first=D. |last=Woolf |year=2008 |month= |format=pdf |work= |publisher= |pages= |quote=
*cite web | title= Watch a short documentary about biochar on Catalyst, Australian science TV| url=http://www.abc.net.au/catalyst/stories/s2012892.htm
*cite web | title= Limitations Of Charcoal As An Effective Carbon Sink | url= http://www.sciencedaily.com/releases/2008/05/080501180247.htm | accessdate=2008-05-19
*
* cite web | title= Johannes Lehmann | url= http://www.css.cornell.edu/faculty/lehmann.html | accessdate=2008-05-24
* cite web | title= Newton P. de Souza Falcao | url= http://www.inpa.gov.br/cpca/newton.html | accessdate=2008-07-30