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?
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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