Towards a circular economy for plastic packaging wastes - the environmental potential of chemical recycling

Plastic packaging waste faces increasingly stringent sustainability targets such as recycling rates of 55% imposed by the European Commission. To realize the vision of a circular economy, chemical recycling is advocated as a large-scale avenue to decrease fossil resource depletion and greenhouse gas (GHG) emissions. In this work, we develop a theoretical model for chemical recycling technologies assuming ideal performance. The theoretical model allows us to compute the minimal environmental impacts for chemical recycling technologies and compare them to real-case benchmark waste treatments. Thereby, we robustly identify chemical recycling technologies that will not result in environmental benefits, since their minimal environmental impacts are already higher than those of current benchmark waste treatments. In this way, we show that PET, HDPE, LDPE, PP and PS should not be recycled chemically to refinery feedstock or fuel products and rather be treated by mechanical recycling and energy recovery in cement kilns in order to reduce global warming impacts. In contrast, chemical recycling to monomers or value-added products could potentially reduce global warming impacts compared to all benchmark waste treatments by up to 4.3 kg CO2-eq per kg treated PET packaging waste. By analyzing 75 waste treatment scenarios for 5 environmental impacts, our analysis offers guidance to stakeholders involved in chemical recycling to identify the most promising as well as the least promising chemical recycling technologies.