Material Flow Analysis and Life Cycle Assessment of Polyethylene Terephthalate and Polyolefin Plastics Supply Chains in the United States

Plastics are useful and beneficial materials that contribute
to
an improved quality of life, yet they generate significant solid wastes
and emissions and consume significant energy resources. Systems analysis
is incomplete on current linear production systems of plastics supply
chains and their associated processes. Our study combines material
flow and life cycle assessment data sets of polyethylene terephthalate
(PET) and the main polyolefin polymers in the United States, comprising
over 70% of plastics flows. This study estimates the total greenhouse
gas (GHG) emissions and energy consumption of these supply chains,
including transportation and end-of-life processes, lacking in prior
studies. We calculate annual GHG emissions and energy consumption
of these plastic supply chains to be 101 MMT CO2-eq and
3248 PJ in 2019, respectively. The GHG emissions of these supply chains
represented 1.5% of the total U.S. emissions and 5% of the total U.S.
industry-related GHG emissions. The total energy consumption of these
supply chains represented 3.1% of the total U.S. energy consumption
in 2019. Transportation of PET and polyolefin plastic materials contributes
5% and 2% to the total supply chain GHG emissions and energy consumption,
respectively. This baseline study provides a benchmark and enables
a comparison to future circular production systems for plastics in
the United States.