While an increasing number of biorefining firms are focusing on converting wood biomass—logs or chips—into biofuels, biochemicals and other bioproducts, scientists are also exploring how best to extract value-added bioproducts from the abundant, yet underuti­lized, fraction of the wood: the bark. Among these is the Bark Biorefinery Consortium, a team of world-class experts in biomaterial, adhesive and polymer sciences, chemistry and chemical engineering, seven industrial partners and several government research organizations engaged in a four-year collaboration led by researchers from the University of Toronto and Lakehead University, in Ontario, Canada. 

According to Ning Yan, principal investigator at the University of Toronto, the BBC is focused on producing two major industrial bioproducts from tree bark. One, she says, is to exploit the inherent aromatic compositional properties within tree bark and produce a substitute for phenolic-based adhesives. The other platform is to break down bark components, either through extraction or chemical conversion, to produce biobased intermediates in polyurethanes or foams, such as isocyanate, which is commonly found in bark-derived foams.

“We hope to be able to produce a more environmentally friendly counterpart and hopefully at a lower cost from a forest residue like bark,” Yan says.

She adds that while the majority of the research is being conducted in the lab, the goal is to demonstrate the processes at pilot scale and envisions existing saw mills integrating the process as a complimentary utilization effort with bark used as hog fuel.

“We already have promising results for the feasibility of an integrated bark biorefinery that could convert the aromatic portions for biobased adhesives and cellulosic fractions that could be converted into foams,” Yan says. “We have demonstrated promise in the lab, but optimization efforts are ongoing to perfect the process.”  —Bryan Sims