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Producing biochar from forest biomass

Date: October 07, 2015


Background

Schematic of converting beetle-killed trees to biochar.
Schematic of converting beetle-killed trees to biochar.
Forests in the West are overgrown and vulnerable to catastrophic wildfires and attacks by insects and disease. Drought and conditions associated with climate change exacerbate the problem and further contribute to deteriorating forest health. Treatments to thin the forests, decrease fuel loads, and clear out insect- and disease-killed trees have proven expensive. There are few markets for small roundwood and virtually no markets for residual material, such as tops, limbs, etc., causing potential bidders to judge many timber sales as economically infeasible. When treatment projects do get carried out, slash piles of residual material are often burned on site, contributing to smoke, air pollution and greenhouse gas emissions.

Key Findings

The use of woody biomass to produce value-added products, especially from residual materials of biomass removal and wood processing, enhances the feasibility of biomass removal and thus forest treatment projects. One way to convert woody biomass into a useable material is through pyrolysis, a process in which organic matter is heated rapidly to high temperatures with limited or no oxygen.

Products from woody biomass include: 1) biochar (biological charcoal), which has potential as a solid fuel, a soil amendment, and a precursor for secondary carbon products, including activated carbon; 2) syngas (synthesis gas), which has potential for energy production and as feedstock for liquid fuels and chemical production; and 3) bio-oil, which has potential for use as heating oil, transportation fuel, or chemical feedstock. Research at the Rocky Mountain Research Station has focused primarily on biochar, and well-established markets exist for activated carbon.

Several potential applications, and thus markets, for biochar exist. As a soil amendment, biochar attracts and holds water, increases ion exchange capacity, makes the soil more porous, and enhances sorption of organic compounds. Such properties enhance soil productivity and facilitate plant growth to reduce erosion and restore compacted, oxidized, and degraded soils. Research also points to horticultural and nursery applications, such as using biochar as a substitute for vermiculite in plant growing media and enhancing nursery media properties, akin to biochar's potential as a soil amendment.

Moreover, biochar is a stable form of carbon that is highly resistant to further decay and remains in the soil for hundreds or thousands of years - implying uses for carbon sequestration. As a precursor to activated carbon, biochar has the potential for use in filters, such as those used in water treatment facilities.

Outcomes and Next Steps

An important outcome of biochar research is the dialogue it has fostered among researchers, industry, and communities. A 2011 symposium held in St. Regis, Montana included panel discussions on a range of topics, including forest restoration, conversion of biomass to biochar and emerging uses for biochar. Information gaps, challenges and next steps were also discussed. Nearly 100 scientists, community members, Forest Service representatives, environmentalists, and entrepreneurs participated in the presentations and discussions.

Station scientists in Fort Collins, Colorado, Missoula, Montana, and Moscow, Idaho are continuing research on the use of biochar as a soil amendment, including soil test plots under a variety of conditions.

Featured Publications

Anderson, Nathaniel (Nate) ; Jones, J. Greg ; Page-Dumroese, Deborah S. ; McCollum, Dan W. ; Baker, Stephen P. ; Loeffler, Daniel ; Chung, Woodam , 2013


Principal Investigators: 
External Partners: 
Various universities and industry groups