(23a) Life Cycle GHG Emissions, Water and Fossil-Fuel Consumption for Polyethylene Furanoate (PEF) and Its Co-Products from Lignocellulosic Biomass Via Furanics Conversion

The growing environmental impact of fossil-fuel derived plastics has motivated researchers to look for alternative solutions. Biobased plastics are one of the promising solutions since it can potentially reduce greenhouse gas (GHG) emissions and fossil-fuel consumption as compared to their fossil-fuel counterparts. Polyethylene furanoate (PEF) is a bioplastic that has been studied as a potential replacement for fossil-based polyethylene terephthalate (PET) resin, one of the most commonly used resins for packaging and synthetic fiber applications. Recent studies show a technical and economic viability of producing PEF and other potential biofuel co-products (i.e., furfuryl ethyl ether (FEE), methyl levulinate (ML), and dimethyl ether (DME)) from a lignocellulosic feedstock via furanics conversion pathways. In this presentation, we investigate three different PEF production pathways and assess cradle-to-gate GHG emissions, fossil-fuel consumption, and water consumption using the Greenhouse Gases, Regulated Emissions and Energy Use in Technologies (GREET) life-cycle analysis (LCA) tool. The system boundary analyzed in this study includes all of the processes involved in the three PEF pathways from cradle to plant gate: wheat straw cultivation & farming, organosolv (or furanosolv) pretreatment, enzymatic hydrolysis (or alcoholysis), glucose isomerization to fructose, furanics production, furanics recovery, furanics oxidation & polycondensation into PEF, furfural recovery, furfuryl ethyl ether (FEE) production, and on-site combined heat and power (CHP) generation. For the co-product allocation methods, mass-allocation is used as a baseline method for both allocations between wheat straw and grain production and among the final products of PEF production (i.e., PEF, FEE, ML, and DME). Electricity net export from the CHP generation is assumed to displace the U.S. average mix grid electricity. Different sensitivity scenarios are also addressed in this study to see the impact of the upstream production of the material inputs and allocation methods on the LCA results. The results showed that all three PEF pathways are net carbon-negative ranging from -0.77 kgCO₂e/kg-PEF (-124% reduction from fossil-based PET) to -1.44 kgCO₂e/kg-PEF (-145% reduction). Fossil-fuel consumption for the three different PEF pathways was also significantly lower than its fossil-fuel counterpart: 13 – 28 MJ/kg-PEF vs. 74 MJ/kg-PET. The GHG emissions and fossil-fuel consumption metrics for the biobased PEF were also better than those for biobased PET (-0.61 kgCO₂e/kg-PET, 51 MJ/kg-PET). However, the water consumption for the biobased PEF production was higher for the two pathways than its fossil-based counterpart (i.e., 10 – 16 L/kg-PEF vs. 6.4L/kg-PET) while only the third pathway for PEF (i.e., 1.2L/kg-PEF) outperformed its fossil-fuel counterpart. These LCA results show that biobased PEF has the potential to reduce fossil energy use and GHG emissions compared with conventional fossil-derived PET, with the tradeoff of increased water consumption for some of the pathways.