Life Cycle Greenhouse Gas Emissions and Water and Fossil-Fuel Consumptions for Polyethylene Furanoate and Its Coproducts from Wheat Straw

Abstract

Polyethylene furanoate (PEF) is a bioplastic that can potentially replace its fossil-fuel counterpart, polyethylene terephthalate (PET), to reduce greenhouse gas (GHG) emissions. A life-cycle GHG, water, and fossil-fuel consumption analysis is conducted for a potential bioplastic alternative for a fossil-based PET resin, or PEF on a kg-resin basis. PEF is assumed to be produced from a lignocellulosic feedstock (i.e., wheat straw) via furanics conversion reactions through three different pathways. The system boundary includes cradle-to-gate processes including feedstock farming, pretreatment, hydrolysis, conversion into furanics, recovery, polymerization into PEF, and on-site combined heat and power (CHP) generation. While electricity export from the CHP plant is assumed to displace the U. S. grid electricity, other coproducts of PEF are assumed to distribute the emissions and energy burdens on a mass basis. The results showed that all three PEF routes achieved significant GHG reduction relative to its fossil-based counterpart (i.e., PET): 134, 139, and 163% reduction for routes 1, 2, and 3, respectively. While fossil-fuel consumptions for all three pathways were also significantly reduced (i.e., 79, 57, and 53% reduction for routes 1, 2, and 3), water consumptions for routes 1 and 2 were increased by 168 and 79%, respectively, while route 3 only achieved reduction (by 77%) relative to fossil-PET. Different sensitivity analyses were conducted, and the results showed that coproduct allocation methods and wheat straw management assumption were the most important. A preliminary analysis on the farmland area and cost required to reduce unit mass of GHGs using PEF to replace PET is also conducted, showing a promising result for both metrics: (i) 3 metric tons of GHGs reduced/ha for all three PEF pathways and (ii) affordable cost of GHG abatement for routes 1 and 2, while route 3 even generated profits.