Biochar - What it is and Why it's Important

Biochar is a high-carbon, fine-grained residue that is produced during pyrolysis of biomass feedstock.

Biochar is a high-carbon, fine-grained residue that is produced via pyrolysis; it is the direct thermal decomposition of biomass in the absence of oxygen (preventing combustion), which produces a mixture of solids (the biochar proper), liquid (bio-oil), and gas (syngas) products.

Biochar for Carbon Sequestration and Farm Soil Health

Gasifiers produce most of the biochar sold in the United States.[1] The gasification process consists of four main stages: oxidation, drying, pyrolysis, and reduction.[2] Temperature during pyrolysis in gasifiers is 250–550 °C (523–823 K), 600–800 °C (873–1,073 K) in the reduction zone and 800–1,000 °C (1,070–1,270 K) in the combustion zone.[3]

Biomass burning and natural decomposition releases large amounts of carbon dioxide and methane to the Earth's atmosphere. The biochar production process also releases CO2 (up to 50% of the biomass), however, the remaining carbon content becomes indefinitely stable.[4] The biochar becomes a long term carbon storage vessel once used an agriculture or industrial application.

Biomass power plants play a critical role in woody biomass management, and can produce power rain or shine. When the biomass used for power is transformed into biochar, it provides a pathway for fixing carbon and sequestering it in soils. Interestingly, this looks a lot like a form of Biomass Energy with Carbon Capture and Storage (BECCS), listed by the International Panel on Climate Change (IPCC) as a key technology for carbon drawdown.[5]

“Biochar is one of a small set of carbon drawdown and utilization strategies identified by the Intergovernmental Panel on Climate Change (IPCC) as ready to deploy in our efforts to stabilize climate,” ~City of Boulder Senior Sustainability and Resilience Policy Analyst Brett KenCairn.

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  1. Amonette, James E; Blanco-Canqui, Humberto; Hassebrook, Chuck; Laird, David A; Lal, Rattan; Lehmann, Johannes; Page-Dumroese, Deborah (January 2021). "Integrated biochar research: A roadmap". Journal of Soil and Water Conservation. 76 (1): 24A–29A. doi:10.2489/jswc.2021.1115A. S2CID 231588371.
  2. Akhtar, Ali; Krepl, Vladimir; Ivanova, Tatiana (5 July 2018). "A Combined Overview of Combustion, Pyrolysis, and Gasification of Biomass". Energy Fuels. 32 (7): 7294–7318. doi:10.1021/acs.energyfuels.8b01678. S2CID 105089787.
  3. Rollinson, Andrew N (1 August 2016). "Gasification reactor engineering approach to understanding the formation of biochar properties". Proceedings of the Royal Society. 472 (2192). Bibcode:2016RSPSA.47250841R. doi:10.1098/rspa.2015.0841. PMC 5014096. PMID 27616911.
  4. Woolf, Dominic; Amonette, James E.; Street-Perrott, F. Alayne; Lehmann, Johannes; Joseph, Stephen (10 August 2010). "Sustainable biochar to mitigate global climate change". Nature Communications. 1 (5): 56. Bibcode:2010NatCo...1...56W. doi:10.1038/ncomms1053. ISSN 2041-1723. PMC 2964457. PMID 20975722.
  5. California Energy Commission. “Biomass Energy in California. California Energy Commission, State of California, (and here)