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Life Cycle Assessment of Sugarcane-Based Polyethylene
Shawn E Hunter, The Dow Chemical Company
Bruno Pereira, The Dow Chemical Company
Richard K Helling,* The Dow Chemical CompanyMany life cycle assessment (LCA) studies have focused on the use of renewable materials as fuels such as ethanol or biodiesel. Limited reports exist for the use of renewable feedstocks in plastics, and these reports often focus on new or specialty materials. In 2007, The Dow Chemical Company announced the formation of a joint venture with Crystalsev to produce polyethylene (PE) from sugarcane-derived ethanol in Brazil (1). This novel use of a renewable feedstock would produce a commodity plastic that is functionally equivalent to current materials. While the use of sugarcane as a feedstock aligns generally with Dow’s 2015 Sustainability Goals (2), life cycle assessment is required to fully understand the advantages of using cane-based PE in place of petrochemical-based PE. We conducted a cradle-to-gate LCA study to understand the environmental tradeoffs between cane-based and petrochemical-based PE. Compared to petrochemical-based PE, cane-based PE exhibits significant advantages in greenhouse gas emissions and fossil fuel consumption. Whereas the production of petrochemical-based PE releases 1.8 kg CO2 eq/kg PE (3), the production of cane-based PE exhibits a net negative cradle-to-gate global warming potential. These advantages arise from the incorporation of biogenic carbon into the product and from the use of bagasse (4) as a renewable energy source for powering the cane to PE process. These results demonstrate that the production of PE from sugarcane can contribute towards achieving reduced greenhouse gas emission goals. While advantaged from a greenhouse gas emissions perspective, cane-based PE may exhibit tradeoffs in other areas, including land use competition, acidification, and eutrophication. We will discuss these and other results of this LCA study.
(1) Dow-Crystalsev JV announcement(link)
(2) Dow’s 2015 Sustainability Goals(link)
(3) Linear Low Density Polyethylene (LLDPE), a report by I. Boustead for PlasticsEurope, March 2005(link)
(4) Bagasse is the biomass that remains after crushing the cane and removing the juice
* corresponding author: rhelling@dow.com