Check it Out: Can Biochar Be Used for Carbon Dioxide Drawdown in Washington State?

By Karen Hills

Bag full of biochar, a black gravelly material
Figure 1. Biochar has the potential to improve agricultural soils and sequester carbon. Source: USDAgov, licensed under CC PDM 1.0.

This is part of a series highlighting work by Washington State University (WSU) researchers through the Waste to Fuels Technology Partnership between the Department of Ecology and WSU during the 2017-2019 biennium.

In a recent study, Jim Amonette at the Pacific Northwest National Laboratory and Washington State University Center for Sustaining Agriculture and Natural Resources developed an improved method to estimate the technical potential for biochar (Figure 1)—made from forestry residues and waste wood (Figure 2) and applied to agricultural soils in Washington State—to store carbon, drawing down atmospheric carbon (C) and contributing to mitigating climate change. Amonette selected twenty-six counties in Washington State for application of this improved method (Figure 3). For each county, Amonette developed seven biomass feedstock and biochar process scenarios including one for waste wood harvested from municipal solid waste alone, and six for waste wood combined with forestry residues from timber harvesting operations. The research generated results for each of the 26 counties.

Oil tank kiln with burning branches inside, and a pile of branches in the surrounding ag field
Figure 2. Biochar can be produced in commercial facilities or by using kilns like this oil tank kiln close to the source of waste wood. Photo: Wilson Biochar Associates; used with permission.

For the 26 counties studied over a period of 100 years, biochar could store between 8 and 411 million metric tons of biochar C, resulting in an immediate offset of between 11 and 354 metric tons of C. These values decrease by 50% if the same sustainably procured biomass were instead combusted for renewable energy. The analysis shows that biochar-C storage capacity is lowest for counties that generate large amounts of woody biomass, and consequently, after a few decades they will need to export their biochar to agricultural counties, located primarily in the southeast quadrant of the state. However, under current storage potential assumptions, the 26-county biochar-C soil storage capacity will be saturated in 54 to 109 years for the scenarios that include timber harvest biomass residues. Amonette added that the development of additional storage technologies and reservoirs such as forest and rangeland soils would allow this limit to be pushed to higher levels.

Map of Washington State counties, with 26 highlighted in different colors.
Figure 3. Dots on the map show the 26 counties selected for this study based on their ranking in four categories relevant to biochar production or use potential: Municipal Solid Waste (pink), Forest Biomass (blue), wildland urban interface Fire Risk (red), and Agricultural Productivity (orange). For explanations of categories and names of counties, see Amonette, 2019. Source: Amonette, 2019.

For more detail, see the brief project report (12 pages, Chapter 6 in Hills et al. 2019) or the longer technical report (Amonette, 2019: 174 pages).


Amonette, JE. 2018. Assessing local technical potentials for CO2 drawdown using biochar from forestry residues and waste wood in Washington State. p. 271-293 (Chpt. 14) in Advancing Organics Management in Washington State: The Waste to Fuels Technology Partnership 2015-2017 Biennium. Washington State Department of Ecology Publication Number 18-07-010.

Amonette, J.E. 2019. Assessment of the Local Technical Potential for CO2 Drawdown using Biochar from Forestry Residues and Waste Wood in 26 Counties of Washington State A technical report completed as part of the Waste to Fuels Technology Partnership. 174 pp.

Hills, K., M. Garcia-Perez, J.E. Amonette, M. Brady, T. Jobson, D. Collins, D. Gang, E. Bronstad, M. Flury, S. Seefeldt, C.O. Stöckle, M. Ayiania, A. Berim, W. Hoashi-Erhardt, N. Khosravi, S. Haghighi Mood, R. Nelson, Y.J. Milan, N. Pickering, N. Stacey, A.H. Tanzil, J. Zhang, B. Saari, and G. Yorgey. Advancing Organics Management in Washington State: The Waste to Fuels Technology Partnership, 2017-2019 Biennium. 2019. Publication 19-07-027. Solid Waste Management Program, Washington Department of Ecology, Olympia, WA.

 This article is also posted on the CSANR Perspectives on Sustainability blog.


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