The National Renewable Energy Lab has conducted a recent study on the use of “advanced” recycling methods in the plastics industry, which involve high heat and chemical additives, is not only costly but also poses significant environmental challenges. The research singles out pyrolysis and gasification as particularly problematic technologies due to their high energy requirements and the emission of pollutants and greenhouse gases. While some states have categorized advanced plastic recycling as a manufacturing process rather than waste disposal, environmentalists argue that converting plastic waste into fossil fuels or feedstocks for more plastic exacerbates environmental damage and worsens climate change.
The study highlights the negative environmental impact of pyrolysis and gasification, indicating that these technologies cannot be considered as “closed-loop” recycling methods. These processes involve the conversion of discarded plastics into oil, fuel, or chemicals such as benzene, toluene, and xylene, leading to significant emissions of synthetic gases and carbon char waste. The large amounts of energy required by these technologies further contribute to their environmental drawbacks.
The research also examines other forms of chemical recycling, which fare better than pyrolysis and gasification in terms of environmental impact. However, the traditional method of mechanical recycling, which involves sorting, cleaning, shredding, and remolding waste plastic, outperforms emerging methods in both economic and environmental aspects, albeit with some technical limitations.
The study sheds light on the substantial challenges faced by the world in managing the staggering amount of plastic waste generated annually, which amounts to 400 million metric tons. The report underscores the fact that plastic waste production has doubled in the last two decades, with only 9 percent of it being recycled. Landfills, incineration, and environmental littering remain the primary disposal methods for the majority of plastic waste.
The research, titled “Technical, Economic, and Environmental Comparison of Closed-Loop Recycling Technologies for Common Plastics,” published in the peer-reviewed journal Sustainable Chemistry & Engineering, thoroughly examines various up-and-coming recycling technologies. The study aims to provide a comprehensive evaluation of these methods based on environmental, economic, and technical criteria. Plastic’s chemical composition, including polymer chains and toxic additives, poses a significant challenge to recycling due to its diverse nature and post-consumer mixing.
The study investigates several chemical recycling approaches that could be considered genuine “closed-loop” solutions. These methods involve using solvents, enzymes, acids, or methanol to break down plastic waste into its chemical building blocks. The researchers analyze different types of plastics, including high- and low-density polyethylene (HDPE and LDPE), polyethylene terephthalate (PET), and polypropylene (PP). However, it should be noted that most of the evaluated technologies, except for mechanical recycling, are still in early development stages or pilot projects.
Proposals advocating for pyrolysis or gasification and seeking regulatory changes at state and federal levels have faced resistance from local communities and national environmental groups. Specific projects, such as a chemical recycling plant in Ashley, Indiana, a proposed plant in Point Township, Pennsylvania, and a proposed waste-to-jet fuel plant in Gary, Indiana, have encountered significant opposition. The role of chemical recycling is also being debated at the United Nations in relation to existing hazardous waste treaties and a proposed global treaty on plastic waste. The chemical industry advocates for chemical recycling as part of a “circular economy,” which aims to achieve a closed-loop system.
