469891 A Discussion of Realistic Feedstocks: Can We Use 2-Year-Old Short Rotation Hybrid Poplar Coppice for Fuels and Chemicals Production Via Biochemical and Thermochemical Conversion?

Wednesday, November 16, 2016: 12:55 PM
Union Square 19 & 20 (Hilton San Francisco Union Square)
Chang Dou1, Devin Chandler2, Fernando Resende1, Rick Gustafson1 and Renata Bura1, (1)School of Environmental and Forest Sciences, University of Washington, Seattle, WA, (2)University of Washington, Seattle, WA

The economic success of a potential biorefinery is directly related to the use of low cost biomass. Due to the high cost, it is unlikely that a wood-based biorefinery would use only whitewood chips from mature trees in conversion. Using a more heterogeneous raw material is less costly, but efficacy of the conversion using whole short ration coppice (including leaves, bark, branches and white wood) has not been investigated. This study investigated the influence of using whole 2-year-old hybrid poplar coppice on the overall sugar yield via biochemical conversion and the bio-oil production via thermochemical conversion.

By harvesting all aboveground parts of 2-year-old hybrid poplar coppice, the biomass used in this study was comprised of 37% leaves, 9% bark, 12% branches, and 42% whitewood chips (dry weight basis). From this, four biomass samples were prepared and studied: 1) 2-year-old poplar mixture, 2) 2-year-old poplar mixture without leaves, 3) 2-year-old poplar leaves, and 4) 12-year-old poplar wood chips. In biochemical conversion, all poplar samples were steam pretreated at 195˚C for 5 minutes with 3% SO2and enzymatic hydrolyzed at 5FPU/cellulose enzyme loadings. The sugar recovery and estimated ethanol yield were calculated. In thermochemical conversion, samples were fast pyrolyzed at 500 ˚C, for 1 second in a fluidized bed reactor. The final bio-oil yield and composition were measured.

Results show that converting the 2-year-old hybrid poplar coppice may be challenging, with up to 50% lower sugar yield and close to 30% lower bio-oil yield than 12-year-old poplar wood chips. However, the removal of leaves significantly increased the overall sugar recovery and bio-oil production by 20% and 15%, respectively. Unsurprisingly, the substrate derived from isolated leaves performed poorly in both biochemical and thermochemical conversion. These results show that leaf removal from 2-year-old hybrid poplar coppice prior to harvest may enhance the biorefinery production. Given the yields of both processes, we will evaluate the economics of converting 2-year-old hybrid poplar coppice to sugar and bio-oil via biochemical and thermochemical conversions.

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