By Plasteurope.com correspondent

The Sustainable Energy and Environmental Systems Department at the US-based Lawrence Berkeley National Laboratory (https://ses.lbl.gov) has found a way to identify the emissions contribution of each step in the plastics production chain. The comprehensive modelling of greenhouse gas (GHG) emissions from global primary plastics production has been detailed by the lab in its report, Climate Impact of Primary Plastic. The research site is managed by the University of California for the US Department of Energy’s Office of Science.

The report focused on major types of fossil-fuel-based plastic polymers produced and consumed in large quantities, and their impact. This includes LDPE, HDPE, LLDPE, polypropylene, PET, PVC, polystyrene, SAN, ABS and polyurethane, which together account for about 80% of plastics production, the report said.

The report asserts that approximately 75% of GHG emissions from primary plastics production occurs from the steps prior to polymerisation, with much of the emissions coming primarily from production of monomers, hydrocarbons, and non-hydrocarbon chemicals. 

Approximately 20% of GHG emissions are generated during extraction and mining of fossil fuels. Roughly 16% occur during the refining and processing of fossil fuels for hydrocarbons such as naphtha and ethane, used to produce monomers. The report says 13% of emissions occur during the production of non-hydrocarbon materials, such as acetic acid, formaldehyde, and chlorine used to produce some monomer types. 

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The production of monomers – the building blocks of polymers, including ethylene, propylene, purified terephthalic acid, vinyl chloride monomer, or styrene – generate more than a quarter of the GHG emissions (26%) that occur during the production stage of primary plastics, according to the report. The polymerisation process generates approximately 8%, while the product-shaping step – the stage where polymers are processed and transformed into final products – is where 17% of GHG emissions occur, according to the report.

The detailed modelling of the primary plastic polymers in which the production value chain stages are fully considered can provide a sound, technically neutral, and scientific foundation to global treaties on climate change seeking to keep the global average temperature rise below 1.5°C to 2°C, the report added.