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Earth Notes: The Future Of Woody Biomass


Forest thinning across northern Arizona is generating tons of small diameter wood and slash. Those byproducts have a limited sales market, so last year a team of researchers at Northern Arizona University began a pilot project in collaboration with the U.S. Forest Service and the Arizona Department of Forestry.

Led by NAU professor Han-Sup Han from the Ecological Restoration Institute, the team brought industrial chippers out to Camp Navajo, south of Flagstaff, and filled 58 shipping containers with wood chips. They were transported by rail, then by sea to South Korea where energy resources are scarce and there is great interest in renewable energy.

Wood chips can be sold in South Korea for double what U.S. markets pay. But at least five million dollars of investments in machinery and railroad infrastructure would be needed to make this ‘chip-and-ship’ trial economically viable.

The NAU team is investigating other products that can be made from the forest thinning debris – like paper pulp and plastic-wood composite decking. Another possibility is ‘pyrolyzing’ the material to make ‘biochar’, a charcoal-like substance which can be added to soils, reducing the need for water and fertilizer.

A more intense version of the roasting process called ‘torrefaction’ produces high-density fuel cubes that can substitute for coal.

Success for all these ideas will depend on developing technological fixes to lower production costs and finding markets willing to pay a little bit more for bio-renewable products.