Sustainability and Environmental Impact Assessment of Polystyrene-toPyrolysis-Oil Conversion: A Life Cycle Evaluation

To evaluate the environmental impacts ofproduction processes andthe use or deployment ofproducts to aiddecision-making, life cycle assessment (LCA) is employed. This study outlines a four-step process for generating condensed information on plastic to pyrolysis oil conversion. An LCA evaluates the environmental impact ofa product or process throughout its entire life cycle. A cradle-to-gate LCA model was applied to analyse the conversion ofplastic waste into pyrolysis oil. Utilising midpoint LCIA (Life Cycle Impact Assessment) techniques, the environmental impact of 1 litre of pyrolysis oil was assessed. Data for this study were sourced from published literature, internet searches, and the Eco-Invent database integrated into the OpenLCA 2.0.0 software. The result from the investigation reveals that the pyrolysis process phase, specifically the "human-health total impact," is the primary source ofenvironmental impact. Methane emissions during this phase, with an impact value of0.00023 kg per kg ofplastic waste, and subsequent nitrate emissions, with an impact value of0.00640 kg per kg ofplastic waste, are identified as significant pollutants. Comparison ofthese values with the U.S. Environmental Protection Agency's (EPA) recommended limits (0.0002 kilograms ofmethane and 0.0065 kilograms ofnitrate) indicates compliance, affirming the safety ofthe pyrolysis process for the environment. The pyrolytic conversion ofplastic waste to pyrolysis oilaligns with the 7th, 12th, and13th Sustainable Development Goals (SDGs) adoptedby the USA in 2023.