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Dead trees for bioenergy

The US department of agriculture (USDA) has awarded nearly US$10 million to an academic, industry, and government consortium led by Colorado State University to study the major challenges limiting the use of insect-killed trees in the Rockies as a sustainable feedstock for bioenergy.

“Infestations of pine and spruce bark beetles have impacted over 42 million acres of US forests since 1996, and a changing climate threatens to expand the threat from bark beetle on our forest lands,” Agriculture secretary Tom Vilsack, says. “As we take steps to fight the bark beetle, this research will help take the biomass that results from bark beetle infestation and create renewable energy that holds potential for job creation.”

There are many benefits to using beetle-killed wood for renewable fuel production. It requires no cultivation, circumvents food-versus-fuel concerns and likely has a highly favourable carbon balance. However, there are some challenges that have been a barrier to widespread use. It is typically located far from urban industrial centres, often in relatively inaccessible areas with challenging topography, which increases harvest and transportation costs. In addition to technical barriers, environmental impacts, social issues and local policy constraints to using beetle-kill wood and other forest residues remain largely unexplored.

“Utilisation of the beetle-kill wood and other waste biomass from forest thinning and fire hazard reduction has great potential for biofuel production,” Keith Paustian, professor at Colorado State University (CSU), says.

Much of the project revolves around feedstock availability inventory and modelling, sustainable feedstock removal practices, transport and processing, and use of the biochar co-product resulting from the pyrolysis of biomass to produce drop-in transportation fuels. The project will undertake comprehensive economic, environmental, and social/policy assessment, and integrate research results into a web-based user-friendly decision support system.

Specifically, the team will explore the potential for scalable thermochemical conversion of beetle-kill wood to advanced liquid biofuels and co-products. The project is working with Cool Planet Energy Systems, based in Greenwood Village, Colorado. The company’s prototype pyrolysis system can be tailored to the amount of feedstock available and thus can be deployed in close proximity to stands of beetle-killed timber. This localised production leads to significantly lower costs related to wood harvest and transportation. Its distributed scalable bio-refinery approach is a key element in making the use of insect-damaged trees as feedstock plausible.