A comprehensive life cycle assessment and life cycle cost analysis of fuel production using pyrolysis of polyethylene terephthalate plastic waste

This study integrates life cycle assessment (LCA) and life cycle cost (LCC) analysis for fuel production through the pyrolysis of polyethylene terephthalate (PET) waste. This novel approach examines two scenarios: advanced and simple pyrolysis, within a case study framework. The system boundary is delineated from the input of 1 t of PET waste as the functional unit (FU) through to the production of pyrolysis oil, natural gas, and petroleum coke as marginal fuels. The ReCiPe2016 impact assessment method is applied to LCA, while capital expenditures (CAPEX) and operational expenditures (OPEX) are analyzed for LCC. A key innovation of this study is the inclusion of the hidden costs associated with environmental damage disposal in the OPEX analysis. Results indicate that advanced pyrolysis, with a climate change benefit of −202 kg CO₂-eq per FU, performs approximately four times better than simple pyrolysis, which shows a benefit of −47 kg CO₂-eq. In most impact categories, the pyrolysis process itself is the main environmental hotspot, while the produced fuels present the primary environmental benefits. The LCC analysis reveals that the total CAPEX for advanced pyrolysis, at $149 per FU, is 50 % higher than that for the simple scenario, primarily due to the costs of purchasing and installing equipment, especially in establishing image processing steps. In terms of OPEX, the simple scenario shows slight advantages due to the absence of catalyst costs. Ultimately, the total LCC for simple and advanced pyrolysis is estimated at approximately -$643 and -$589 per FU, respectively. It can be concluded that environmentally, advanced pyrolysis is always preferable, while economically, starting with catalysts to enhance pyrolysis, followed by adopting image processing technology for automated feedstock sorting, improving purity, pyrolysis efficiency, and fuel yield, offers a strategic progression.