ABSTRACT
BACKGROUND: The overall goal of the present study is to investigate the economics of an integrated biorefinery converting hybrid poplar into jet fuel, xylitol, and formic acid. The process employs a combination of integrated biological, thermochemical, and electrochemical conversion pathways to convert the carbohydrates in poplar into jet fuel, xylitol, and formic acid production. The C5-sugars are converted into xylitol via hydrogenation. The C6-sugars are converted into jet fuel via fermentation into ethanol, followed by dehydration, oligomerization, and hydrogenation into jet fuel. CO2 produced during fermentation is converted into formic acid via electrolysis, thus, avoiding emissions and improving the process's overall carbon conversion. RESULTS: Three different biorefinery scales are considered: small, intermediate, and large, assuming feedstock supplies of 150, 250, and 760 dry ktonne of poplar/year, respectively. For the intermediate-scale biorefinery, a minimum jet fuel selling price of $3.13/gallon was obtained at a discount rate of 15%. In a favorable scenario where the xylitol price is 25% higher than its current market value, a jet fuel selling price of $0.64/gallon was obtained. Co-locating the biorefinery with a power plant reduces the jet fuel selling price from $3.13 to $1.03 per gallon. CONCLUSION: A unique integrated biorefinery to produce jet fuel was successfully modeled. Analysis of the biorefinery scales shows that the minimum jet fuel selling price for profitability decreases with increasing biorefinery scale, and for all scales, the biorefinery presents favorable economics, leading to a minimum jet fuel selling price lower than the current price for sustainable aviation fuel (SAF). The amount of xylitol and formic produced in a large-scale facility corresponds to 43% and 25%, respectively, of the global market volume of these products. These volumes will saturate the markets, making them infeasible scenarios. In contrast, the small and intermediate-scale biorefineries have product volumes that would not saturate current markets, does not present a feedstock availability problem, and produce jet fuel at a favorable price given the current SAF policy support. It is shown that the price of co-products greatly influences the minimum selling price of jet fuel, and co-location can further reduce the price of jet fuel.
ABSTRACT
Cellulose nanofibrils are typically prepared from high-purity bleached pulp through harsh chemical treatments (e.g., TEMPO oxidation), resulting in high costs and environmental impact. In this work, we utilize inexpensive wheat straw feedstock and alkaline peroxide pulping followed by mild peracetic acid (PAA) pretreatment to produce lignocellulosic nanomaterials (nano and microfibrils) with potential bioplastics applications. PAA was chosen due to its biodegradability, non-toxicity, and high reaction selectivity. As-synthesized lignocellulosic nanomaterials were thoroughly characterized and compared to nanofibrils produced via TEMPO oxidation pretreatment and then applied as reinforcing agents in plastic composites. A remarkable case of simultaneous strengthening and toughening of the polymer nanocomposite was achieved with high specific tensile strength (up to 59.5 MPa g-1 cm3), elastic modulus (up to 2.6 GPa g-1 cm3), and fracture strain (up to 138 %). This work is a comprehensive investigation of all process steps involved in lignocellulosic nanomaterials production, from original residue feedstock to final product application.
