Attributes and policy points
A selection of literature references supporting an expanded role for biochar in the environment and economy
Photosynthesis does the heavy lifting: Biochar comprises half of the carbon embodied in the source biomass and removes it from the atmospheric cycle for hundreds to thousands of years.1
Proven in the enviroment over long time scales: Pyrogenic carbon has accumulated in soils wherever a fire regime is in place.2 Globally, landscape fire converts over 250 MT of biomass carbon to stable form every year.3 We can harness this process in a more controlled manner by producing biochar at scale.
No external energy required: With appropriate feedstocks, there is a net energetic yield that is useful for process heat, cogeneration, and displacing fossil fuels.4 This provides yet another potential revenue stream to solidify the business case.
Passes muster under international standards: Biochar is a negative emissions technology (NET) recognised by the IPCC and has the potential to draw down over 15% of CO2 emissions globally.5
Carbon markets aren’t waiting for the ETS to catch up: Voluntary markets for international carbon removal credits are paying biochar producers at rates ranging from 100-500€ per tonne CO2e.6
Benefits in productive soils and stock: Biochar contributes increased water and nutrient retention,7 improved structure and aeration,8 and enhanced biological activity9 leading to stable or increased stocks of organic soil carbon over the long term. As a livestock feed supplement, biochar helps lower parasite burdens and boost animal health in general.10
On-farm mitigation attributes: Biochar can be made from manure solids and other secondary resources, and can reduce GHG efflux from N fertiliser and urine patches on pastoral soils.11 In vitro and in vivo trials of feeding biochar to ruminants have shown promise in methane reduction.12 The animals then do the work of spreading it across the pasture.
Not all soil carbon is equally safe or stable: Labile soil carbon stocks can be diminished through tilling,13 overuse of N fertiliser,14 or land use conversion.15 Biochar in soil is not at risk from these and other adverse management or environmental changes. Erosion simply moves the biochar somewhere else without altering its carbon storage capacity...even if it's washed into the sea it is still a long-term sink.
Effective water quality remediation: Biochar can be used for filtration and adsorption of contaminants, such as excess nitrate concentrations.16 Periodic renewal of the substrate then transfers the loaded material to productive soils, where the bound nutrients are made available to soil life and plants without the risk of leaching.17
Mass reduction of woody debris: Pyrolysis can take the mounting problem of forestry slash and turn it into valuable energy and biochar.18 In situ processing reduces the volume of material by 75%. Stationary facilities can be commissioned to accept high moisture content feedstock, and the thermal output can power cogeneration to provide electricity supply resilience to isolated regions.
1 Lehmann, J., & Joseph, S. (Eds.). (2015). Biochar for Environmental Management: Science, Technology and Implementation (2nd ed.). Routledge. https://doi.org/10.4324/9780203762264
2 Mao JD, Johnson RL, Lehmann J, Olk DC, Neves EG, Thompson ML, Schmidt-Rohr K. Abundant and stable char residues in soils: implications for soil fertility and carbon sequestration. Environ Sci Technol. 2012 Sep 4;46(17):9571-6. doi: 10.1021/es301107c. Epub 2012 Aug 20. PMID: 22834642.
3 Jones, M. W., Santín, C., van der Werf, G. R., & Doerr, S. H. (2019). Global fire emissions buffered by the production of pyrogenic carbon. Nature Geoscience, 12(9), 742–747. https://doi.org/10.1038/s41561-019-0403-x
4 Crombie, K. and Mašek, O. (2015), Pyrolysis biochar systems, balance between bioenergy and carbon sequestration. GCB Bioenergy, 7: 349-361. https://doi.org/10.1111/gcbb.12137
5 de Coninck, H., A. Revi, M. Babiker, P. Bertoldi, M. Buckeridge, A. Cartwright, W. Dong, J. Ford, S. Fuss, J.-C. Hourcade, D. Ley, R. Mechler, P. Newman, A. Revokatova, S. Schultz, L. Steg, and T. Sugiyama, 2018: Strengthening and Implementing the Global Response. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 313-444, doi:10.1017/9781009157940.006
6 https://puro.earth/CORC-co2-removal-certificate/?carbon_removal_method%5B0%5D=7363 Access date 2023-02-23
7 Artiola, J. F., Rasmussen, C., & Freitas, R. (2012). Effects of a biochar-amended alkaline soil on the growth of romaine lettuce and bermudagrass. Soil Science, 177(9), 561-570. https://doi.org/10.1097/SS.0b013e31826ba908
8 Awad, Y.M., Blagodatskaya, E., Ok, Y.S. and Kuzyakov, Y. (2013), Effects of polyacrylamide, biopolymer and biochar on the decomposition of 14C-labelled maize residues and on their stabilization in soil aggregates. Eur J Soil Sci, 64: 488-499. https://doi.org/10.1111/ejss.12034
9 Johannes Lehmann, Matthias C. Rillig, Janice Thies, Caroline A. Masiello, William C. Hockaday, David Crowley, Biochar effects on soil biota – A review, Soil Biology and Biochemistry, Volume 43, Issue 9, 2011, Pages 1812-1836, ISSN 0038-0717, https://doi.org/10.1016/j.soilbio.2011.04.022
10 Schmidt HP, Hagemann N, Draper K, Kammann C. The use of biochar in animal feeding. PeerJ. 2019 Jul 31;7:e7373. doi: 10.7717/peerj.7373. PMID: 31396445; PMCID: PMC6679646.
11 Cayuela ML, Sánchez-Monedero MA, Roig A, Hanley K, Enders A, Lehmann J. Biochar and denitrification in soils: when, how much and why does biochar reduce N₂O emissions? Sci Rep. 2013;3:1732. doi: 10.1038/srep01732. PMID: 23615819; PMCID: PMC3635057.
12 Thomas M Winders, Melissa L Jolly-Breithaupt, Hannah C Wilson, James C MacDonald, Galen E Erickson, Andrea K Watson, Evaluation of the effects of biochar on diet digestibility and methane production from growing and finishing steers, Translational Animal Science, Volume 3, Issue 2, March 2019, Pages 775–783, https://doi.org/10.1093/tas/txz027
13 Bandyopadhyay, K.K. (2020). Effect of Tillage on Soil Carbon Sequestration. In: Ghosh, P., Mahanta, S., Mandal, D., Mandal, B., Ramakrishnan, S. (eds) Carbon Management in Tropical and Sub-Tropical Terrestrial Systems. Springer, Singapore. https://doi.org/10.1007/978-981-13-9628-1_13
14 Mulvaney RL, Khan SA, Ellsworth TR. Synthetic nitrogen fertilizers deplete soil nitrogen: a global dilemma for sustainable cereal production. J Environ Qual. 2009 Oct 29;38(6):2295-314. doi: 10.2134/jeq2008.0527. PMID: 19875786.
15 Guo, L. B., & Gifford, R. M. (2002). Soil carbon stocks and land use change: a meta analysis. Global Change Biology, 8(4), 345–360. https://doi.org/10.1046/j.1354-1013.2002.00486.x
16 Pokharel, A., Acharya, B., & Farooque, A. (2020). Biochar-Assisted Wastewater Treatment and Waste Valorization. Applications of Biochar for Environmental Safety. doi: 10.5772/intechopen.92288
17 Gwenzi W, Chaukura N, Noubactep C, Mukome FND. Biochar-based water treatment systems as a potential low-cost and sustainable technology for clean water provision. J Environ Manage. 2017 Jul 15;197:732-749. doi: 10.1016/j.jenvman.2017.03.087. Epub 2017 Apr 25. PMID: 28454068.
18 Hall P. (2022) Residual biomass fuel projections for New Zealand; 2021 - Indicative availability by region and source. Scion Report https://www.usewoodfuel.org.nz/documents/resource/Woody-biomass-residues-and-resources-2021-Feb2022_V5.pdf