Hikers in some areas know them well, and so does anyone with intense yard work experience: the slash pile. A new high-tech blanket developed promises to transform these awkward plant scrap mountains into several useful green products.
Since the piles contain stumps and other woody chunks, sawmills and paper mills have little use for them. Hauling the material offsite to be processed into fuel would be cost-prohibitive. Usually the slash piles that are especially common in the Pacific Northwest are either left to rot or subject to controlled burning in order to prevent forest fires. Can you say "excess CO2 emissions?"
To prevent that, University of Washington chemical engineering professor Daniel Schwartz, along with students that included forestry resources PhD candidate Jenny Knoth, looked for a way to make fuel from slash piles without having to move them. They came up with what they're calling a "pyrolysis blanket" that wraps around the pile, causing the waste to smolder into a charcoal-like substance.
The blanket is made from a heat-resistant laminate that's also impermeable to air. Adjustable vents in the material allow for the airflow to be controlled depending on the desired effect, according to Mara Grunbaum of Ecomagination.com. When a slash pile is burned under the blanket, the lack of oxygen creates a form of solid carbon known as "biochar."
Knoth, along with fellow students Ken Faires, Derek Churchill, Nate Dorin and John Tovey III, created a startup now known as Carbon Cultures to further develop the blanket. Last year they received a $50,000 National Science Foundation grant for support.
Readers familiar with biochar know the stuff as a potential geoengineering approach because making it prevents CO2 formation. When added to soil, biochar boosts agricultural yields so farmers, landscapers and gardeners love and value it. Biochar can also be burned as a greener alternative to mined coal.
The Carbon Cultures team says its blanket can process small slash piles into biochar within a day, and they call the low-cost technology easy for forestry crews to use. This summer the students plan to test their blanket on large slash piles and make adjustments to reduce soot and emissions further from the process, Grunbaum reported. Just in time for outdoor grilling season.
Photo: Slash piles like this one at Taylor Mountain in Washington could be transformed into fuel with a new blanket in development. Credit: Monty VanderBilt