- Chemical recycling
- Advanced recycling
- Enhanced recycling
- Thermal recycling
- Tertiary recycling
- Thermal cracking
- Catalytic cracking
- Mechanical or conventional recycling
- Circular economy
Chemical recycling, also known as advanced or tertiary recycling,((Thiounn, T., & Smith, R. C. (2020). Advances and approaches for chemical recycling of plastic waste. Journal of Polymer Science, 58(10), 1347-1364. https://doi.org/10.1002/pol.20190261)) is a group of processes that uses heat, pressure, and/or chemical solvents to break plastic waste into its basic building blocks, which can then be remade into new plastic.
Due to misuse of the term, chemical recycling is often confused with “plastic-to-fuel” processes that break plastic waste down into liquids or gases before burning them as fuel. While some of the technical processes involved are the same for chemical recycling as for plastic-to-fuel, processing plastic waste so that it can be burned is not recycling, and any thermal or chemical treatment should only be called chemical recycling if the end result is new plastic.
Bans & Restrictions
Currently there are no bans on chemical recycling. The EU Waste Framework Directive includes chemical recycling in its overall definition of recycling, but limits the definition to processes that turn waste material into new products rather than into materials to be used as fuel. ((Directive 2008/98/EC of the European Parliament and of the Council on waste and repealing certain directives. OJ L 312 22.11.2008, p. 3. http://data.europa.eu/eli/dir/2008/98/2018-07-05))
In theory, chemical recycling offers an interesting approach to managing plastic waste, particularly for plastics that are otherwise difficult to recycle. In practice, however, it is technologically immature, economically infeasible, logistically challenging, has a significant carbon footprint, and results in toxic byproducts that threaten human and ecological health.
Chemical recycling struggles to deliver its basic promise of turning plastic waste into new plastic. While it is theoretically possible to have minimal or even nonexistent losses of plastic material in chemical recycling, in practice, each loop through the process results in significant losses of raw material, perpetuating the need for new plastic inputs.((Eunomia. (2020). Chemical Recycling: State of Play. CHEMTrust. https://chemtrust.org/wp-content/uploads/Chemical-Recycling-Eunomia.pdf)) Often, material is lost in pre-sorting, burned up in the treatment process itself (producing harmful emissions), or too contaminated or low quality to be used for new plastic. Most plastic products include a wide range of additives, further complicating chemical recycling.
Data from a chemical recycling facility shows that as much as 35% of plastic input material can be lost in the recycling process.((Patel, D., Moon, D., Tangri, N., Wilson, M. (2020). All Talk and No Recycling: An Investigation of the U.S. “Chemical Recycling” Industry. Global Alliance for Incinerator Alternatives. www.doi.org/10.46556/WMSM7198)) Chemical recycling’s proposed “circularity” is further hampered by the infrastructure and incredible amounts of energy required for operation. Energy is needed to sort feedstock materials, run machinery, provide large amounts of heat for thermal treatment, and clean the toxic byproducts created in the process. These energy inputs in turn contribute to carbon emissions and raise production costs, so much so that chemically recycled plastic struggles to compete with low-cost virgin plastic.((Brock, J., Volcovici, V., Geddie, J. (July 29, 2021). The Recycling Myth: Big Oil’s Solution for Plastic Waste is Littered with Failure. Reuters. https://www.reuters.com/investigates/special-report/environment-plastic-oil-recycling/))((Patel, D., Moon, D., Tangri, N., Wilson, M. (2020). All Talk and No Recycling: An Investigation of the U.S. “Chemical Recycling” Industry. Global Alliance for Incinerator Alternatives. www.doi.org/10.46556/WMSM7198)) The material losses and energy inputs described above make chemical recycling an energy-intensive project with a large carbon footprint.
Based on data from one chemical recycling facility, 3.9 kilograms of CO2 can be emitted for every 1 kilogram of new plastic produced, not including the lifecycle carbon emissions associated with the production of the original plastic waste used as an input, or the emissions associated with post-processing.((Patel, D., Moon, D., Tangri, N., Wilson, M. (2020). All Talk and No Recycling: An Investigation of the U.S. “Chemical Recycling” Industry. Global Alliance for Incinerator Alternatives. www.doi.org/10.46556/WMSM7198))
These limitations are reflected most plainly by the fact that chemical recycling is almost non-existent in the real world. Data from the US shows that out of 37 proposed chemical recycling projects since 2000, only 3 were operational as of 2020, and none successfully produced new plastic at a commercial scale.((Patel, D., Moon, D., Tangri, N., Wilson, M. (2020). All Talk and No Recycling: An Investigation of the U.S. “Chemical Recycling” Industry. Global Alliance for Incinerator Alternatives. www.doi.org/10.46556/WMSM7198)) Notably, in the case of thermal cracking systems, the most widespread technology for chemical recycling, plants that are labeled as chemical or advanced recycling facilities in reality burn most or all of what they ultimately produce, making them in effect plastic-to-fuel plants.((Patel, D., Moon, D., Tangri, N., Wilson, M. (2020). All Talk and No Recycling: An Investigation of the U.S. “Chemical Recycling” Industry. Global Alliance for Incinerator Alternatives. www.doi.org/10.46556/WMSM7198))((Zero Waste Europe et al. (2020). Understanding the Environmental Impacts of Chemical Recycling – Ten concerns with existing life cycle assessments. https://zerowasteeurope.eu/library/understanding-the-environmental-impacts-of-chemical-recycling-ten-concerns-with-existing-life-cycle-assessments/))
While there is very little transparency on the part of chemical recycling plants about their emissions and byproducts, these facilities likely operate similarly to others in the petrochemical industry, which produce large amounts of toxic air pollutants, liquid effluent, and solid waste. In one pilot chemical recycling plant for multilayer plastic packaging, as much as 25-40% of the input material was converted to waste.((Personal communications with Yuyun Ismawati Drwiega at the Nexus3 Foundation.)) Moreover, chemically and thermally treating plastic waste is known to release many toxins, including some that are already banned by national regulations, such as bisphenol-A (BPA), cadmium, and benzene, among many others.((Rollinson, A., Oladejo, J. (2020). Chemical Recycling: Status, Sustainability, and Environmental Impacts. Global Alliance for Incinerator Alternatives. https://doi.org/10.46556/ONLS4535)) The toxicity, fate, and characteristics of the residues created by decontaminating plastic waste have not been made public, nor have the hazards associated with the proprietary catalysts used in depolymerization.((Bell, L., & Takada, H. (2021). Plastic Waste Management Hazards. San Francisco: International Pollutants Elimination Network. ISBN 978-1-955400-10-7. https://ipen.org/sites/default/files/documents/ipen-plastic-waste-management-hazards-en.pdf)) This varied and poorly studied waste stream represents a significant hazard for chemical recycling, particularly for developing countries that do not have the appropriate facilities to manage new forms of mixed toxic waste.
Finally, the facilities themselves, as well as the facilities that process their end products and/or toxic waste, are often sited in low-income communities and communities of color already facing significant health burdens from existing industrial emissions.((Patel, D., Moon, D., Tangri, N., Wilson, M. (2020). All Talk and No Recycling: An Investigation of the U.S. “Chemical Recycling” Industry. Global Alliance for Incinerator Alternatives. www.doi.org/10.46556/WMSM7198)) Investing in more chemical recycling plants means increasing the pollution burden on these communities while providing little to no tangible benefits to the world at large.
All in all, the material losses, energy inputs, and environmental hazards associated with chemical recycling make it an expensive and poor strategy for solving the plastics crisis.