This study was originally published on the ACS Sustainable Chemistry and Engineering website.
Abstract
The rapid expansion of the plastic industry has led to significant environmental challenges, prompting the exploration of alternative recycling methods. While mechanical recycling has limitations, chemical recycling, particularly pyrolysis, presents a promising solution. However, it faces contention regarding its environmental impacts and economic feasibility. In this perspective, we analyze both supporting and opposing viewpoints of plastic pyrolysis, highlighting the need for transparent, comprehensive, and measurement-informed life cycle assessments (LCAs) of pyrolysis systems to inform decisions. We also present a case study of literature-reported greenhouse gas (GHG) emissions from pyrolysis-derived ultralow sulfur diesel (ULSD) in the United States, showing that depending on plant capacity and co-product allocation methods, emissions can range from 28% lower to 30% higher than fossil-derived ULSD. Similarly, when viewed as a waste management strategy, net GHG emissions from plastic pyrolysis can range from 220% lower to 60% higher than those from current U.S. plastic waste management practices, depending on system conditions. These findings underscore the variability of results and the need for currently missing, robust, and contextualized LCAs. Finally, we discuss regulatory and social challenges and opportunities for the wider adoption of chemical recycling, emphasizing the critical role of public support in realizing the potential of pyrolysis for a circular economy.
