Slash and build: Study aids forestry biofuel industry

By Siddharth Vodnala, intern, Voiland College of Engineering and Architecture

slash map of northwestPULLMAN, Wash. – Researchers from Washington State University, along with those from Oregon State University and the University of Montana, have recently devised refined methods to estimate the amount of forest residue — the leftovers from trees after logging — that is available for wood-based biorefineries to use.

The resulting research model could help entrepreneurs determine sites for future biorefineries by providing a better understanding of the availability of forest residue, more commonly known as slash, in the region.

Wood waste to jet fuel

Wood-based biorefineries use the slash to make isobutanol and then to convert it into jet fuel.

Last November, Alaska Airlines used a blend of traditional jet fuel and wood-based fuel to fly a jet from Seattle to Washington D.C, as a demonstration flight. The wood-based fuel came from timber harvested in the Pacific Northwest, which has some of the most extensive forest cover in the nation and a high potential for wood-based biorefineries.

Sustainable jet biofuels can reduce the environmental impact of aviation, empower rural economies and increase the nation’s energy security.

Slash from mills included

map of slash in northwest region
Map of available slash from mills in the Pacific Northwest

While previous methods used county-level slash data to estimate the amount of wood residue available as a feedstock, the new research reported in the journal Biomass and Bioenergy, uses more refined data on demand from individual sawmills, said Natalie Martinkus, one of the authors of the paper and an assistant professor in WSU’s Composite Materials and Engineering Center.

Two methods were used in the research to estimate feedstock availability — one was based on publicly available data and the other used a bioeconomic model to simulate forest growth and harvest through time, based on market demand for timber.

The researchers also created models that would simulate the harvest and the resulting slash at a number of locations across the nation and then validated their simulations against data gathered by the University of Montana.

Federal lands targeted

The next step for their research, which has been limited to private and industrial forests, is to expand into federal lands and use data from there, said Martinkus.

“We hope our research will further spur interest in renewable biofuels,” she added.

The research was funded through the U.S. Department of Agriculture through the Northwest Advanced Renewables Alliance, a five-year research project that ended in 2016.



  • Brett Stav, public relations/marketing director, Voiland College of Engineering and Architecture, 509-335-8189,
  • Natalie Martinkus, assistant professor, Composite Materials and Engineering Center, 509-307-5724,