Life Cycle Assessment shows shrinking environmental footprint of plastic production

The American Chemistry Council (ACC) has published the second of three reports analysing the potential environmental impact of plastic resins through their life cycle assessments (LCAs).

The new report compares the carbon dioxide (CO2) emissions and total energy consumption of High Impact Polystyrene (HIPS), General Purpose Polystyrene (GPPS), and Acrylonitrile Butadiene Styrene (ABS) from 2010 to 2020. Last year’s report focused on LDPE, HDPE, LLDPE, and PP.

The LCAs follow the cradle-to-gate model, meaning they assess the product’s environmental footprint from raw materials extraction until it leaves the factory. Data used in the LCAs was collected from 2003-2005 for the 2010 series and between 2015-2017 for the 2020 series. Franklin Associates, a consulting firm associated with the Eastern Research Group (ERG), performed the LCAs with data provided by resin manufacturers with US facilities. The metrics and findings in the report are measured per 1,000 kg of each resin.

Results show a clear trend of decreases in both impact categories ranging from 4% to 22% in CO2 and 7% to 16% in total energy consumption. On average, greenhouse gas emissions decreased by 13% per kilogram of resin produced, equivalent to removing 440,000 cars from our roads for one year.

HIPS

HIPS results show a 6% decrease in CO2 emissions from 2,799 kg to 2,641 kg. The ACC said the decrease can be attributed to the shift in fuel composition used to produce HIPS. In particular, there was a 7% decrease in petroleum used in production and an 9% increase in natural gas, as well as a slight 2% decrease in the use of coal. The combustion of natural gas emits approximately 30% less carbon dioxide than the combustion of petroleum.

In terms of energy use, HIPS production consumed 8% less energy in 2020 compared to 2010, from 96.1 gigajoule (GJ) to 88.5 GJ. “The data suggests that the decrease reflects a decrease in energy consumed at the olefins plant, where some of the material inputs used to produce HIPS resin were produced. The energy decrease can also be attributed to improvements in the oil and natural gas extraction and refining processes,” the report says.

GPPS

GPPS results show a 4% decrease in CO2 emissions from 2,787 kg to 2,667 kg. There was a 7% decrease in petroleum used in GPPS production and an 8% increase in natural gas, as well as a 2% decrease in coal.

Energy consumed decreased from 95.2 GJ in 2010 to 88.2 GJ in 2020, a 7% drop. The report suggests the decrease in total energy consumption can be attributed to efficiency improvements within the production processes, as well as a decrease in energy required for the olefins production and natural gas refinement.

ABS

ABS results show a 22% decrease in CO2 from 3,287 kg to 2,576 kg. “The greater reduction in CO2 emissions can be attributed to the shift in fuel composition, particularly a 5% decrease in coal and 11% increase in natural gas,” the report says.

There was also a 16% decrease in energy consumed from 105 GJ in 2010 to 87.7 GJ in 2022. The notable decrease in energy consumption can be attributed to a decrease in

the amount of styrene used to produce the ABS resin, as well as the decrease in energy required at the ABS resin plant, according to the ACC.  

The ACC expects the positive trend toward lower energy use to continue into the future, due to efficiency improvements in the production of resins and their precursors.