(66e) Techno-Economic and Environmental Life Cycle Assessments of Hydrocarbon Biofuel from Loblolly Pine
Aspen Plus process simulation package was used to model the two stage torrefaction-fast pyrolysis process with catalytic upgrading of pyrolysis bio-oil to hydrocarbon fuel blends. The effect of torrefaction severity on product composition, yield of pyrolysis bio-oil and subsequently yield of hydrocarbon fuel were obtained from the literature.1-6 The effect of torrefaction on the energy requirement for size reduction was also included in our model based on literature data.7 Using these data sources, mass and energy balances were obtained, and used in sizing the equipment, with equipment prices estimated from a number of sources such as the Aspen Economic Process Analyzer, previous works and equipment vendors. A Discounted Cash Flow Rate of Return spreadsheet was used to obtain the gate cost of production, and data obtained from the simulation also served as inputs for the LCA carried out using the LCA software SimaPro 8.0 with greenhouse gas emissions (GHG) as the impact category.
From our model simulations, having a torrefaction step as a pretreatment step prior to fast pyrolysis reduces the cost of bio-oil production from loblolly pine, by reducing energy cost associated with size reduction. Results from the model also show a reduction in GHG emissions associated with the bio-oil production and catalytic upgrading as a result of the torrefaction pretreatment step. The effect of substituting renewable energy (char) for process heat demand rather than natural gas yielded a cost of production decrease from $4.26/gallon hydrocarbon fuel to $4.15/gallon for the one-step pyrolysis-based process. Full results on the TEA and LCA for all scenarios will be presented.
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