University of Washington researchers find poplar coppice could be best bet for Pacific Northwest biofuels

December 18, 2017 |

In Washington state, a University of Washington team is trying to make poplar a viable competitor by testing the production of younger poplar trees that could be harvested more frequently — after only two or three years — instead of the usual 10- to 20-year cycle. The team is the first to try converting the entire young tree — including leaves, bark and stems — into bio oil, a biologically derived oil product, and ethanol using two separate processes. Their results, published this summer in two papers — one in ACS Sustainable Chemistry & Engineering and the other in Biotechnology for Biofuels — point to a promising future for using poplar coppice for biofuel.

The UW team first tested whether entire young poplar trees could be converted into sugar by a process that uses high temperature, pressure and enzymes to break down the wood materials into sugar. From there, it is possible to make ethanol, acetic acid, lactic acid and other valuable chemicals by fermenting the sugar.

After processing the trees, the researchers found that leaves are poor performers and lowered the overall sugar output, not just because leaves are naturally low in sugar, but they also contain other chemicals that impede the sugar-releasing process. When scaled up to a commercial operation, leaves should be removed and may be used for other purposes, such as feed for animals.

They also tested whole poplar trees from the same plot using pyrolysis. Research is underway to convert this dark brown oil to a transportation fuel that resembles gasoline or diesel.

Ultimately, the researchers say that coppice poplar is likely the best balance of cost and reliability for Pacific Northwest growers to produce biofuel.

More on the story.

Category: Research

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