Petite Poplars for Biofuel Production

Poplar trees are one of the best picks as biofuel feedstock due to their abundance, fast-growth, adaptability and their wood can be transformed into substances used in biofuel and high-value chemicals. However, a commercial-scale processing plant for poplars has yet to be achieved. This is mainly because production costs still are not competitive.

 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. These trees are planted closer together and cut in such a way that more branches sprout up from the stump after each harvest, using the same root systems for up to 20 years. This method is called "coppicing," and the trees are known as poplar coppice.

The UW team first tested the conversion of the entire young poplar trees into sugar using high temperature, pressure and enzymes to break down the wood into sugar. From there, it is possible to make ethanol, acetic acid, lactic acid and other valuable chemicals by fermenting the sugar. These results proved that poplar coppice can be a good option to meet the cheap, high-volume criteria of biofuel feedstock.

The researchers then concluded that coppice poplar is likely the best balance of cost and reliability for growers to produce biofuel.