Conversion of 2-year-old short rotation hybrid poplar to bio-oil

The economic success of a potential biorefinery is directly related to the use of low cost biomass. It is unlikely that a wood-based biorefinery would use only whitewood chips from mature trees. Using a more heterogeneous raw material is less costly, but little is known about the efficacy of converting whole short rotation trees.

This study investigated the influence of using whole hybrid poplar on the bio-oil production through fast pyrolysis. Fast pyrolysis is a thermal decomposition process that occurs with a high heat transfer rate to the biomass particles. The product, bio-oil, is a complex liquid mixture composed of oxygenated hydrocarbons. The bio-oil has a heating value about half that of conventional fuel and can be combusted in boiler or upgraded to potential transport fuel.

By harvesting all aboveground parts of 2-year-old hybrid poplar, the biomass was obtained. We studied three poplar samples: 1) 2-year-old poplar mixture, 2) 2-year-old poplar mixture without leaves, and 3) 12-year-old mature tree whitewood chips. All poplar samples were fast pyrolyzed at 500 ˚C, for 1 second in a fluidized bed reactor and the final bio-oil yields were measured.

Generally, the chemical composition of bio-oil generated from three poplar samples was similar. Phenol and acetic acid are presented in the highest concentrations in the product. The yield of each sample is slightly different. For example, the whole 2-year-old hybrid poplar mixture produced 54% bio-oil, 19% char and 13% gas. In this presentation, we will show that leaves removal can increase bio-oil yield.