Plastics are complex, heterogeneous chemical polymers with varying amounts of thousands of chemical additives that impart properties such as color, flexibility, stability, water repellency, flame retardance, and ultraviolet resistance. While many plastic products have obvious benefits, throughout their lifecycles — from production to use, recycling, and disposal — plastic polymers and their additives are also responsible for extensive harm to human health and the environment.
According to a recent report by the Monaco Commission on Plastics and Human Health:
“Single-use plastics account for 35-40% of current plastic production and represent the most rapidly growing segment of plastic manufacture. Explosive recent growth in plastics production reflects a deliberate pivot by the integrated multinational fossil-carbon corporations that produce coal, oil and gas and that also manufacture plastics. These corporations are reducing their production of fossil fuels and increasing plastics manufacture.”
The increasing production and use of plastics will exacerbate the already severe problem of inadequate recycling. From the above report:
“Plastic disposal is highly inefficient, with recovery and recycling rates below 10% globally.”
With growing recognition of this problem, plastics producers are increasingly promoting so-called “advanced recycling.” In particular, two technologies – pyrolysis and gasification – are being widely promoted by the plastics industry as a means to increase recycling rates.
What is “recycling?”
In order to understand what these and other technologies entail, here is some basic terminology that will help those watching, or participating in, the plastics production, disposal, and recycling debate:
- Mechanical recycling: This refers to collecting plastic, sorting, crushing, shredding, removing impurities, and melting into granules that can be used to make new products. This approach largely preserves the original molecular structure, although new products are often of lower quality than the original.
- Advanced recycling, also called molecular recycling or chemical recycling, is a term that encompasses several technologies. All of these technologies use heat, solvents, enzymes, or microwaves to break down plastic waste. The result is a set of monomers, polymers, oligomers, and mixtures of other hydrocarbons.
Currently, among the so-called “advanced recycling” methods, there have been attempts to commercialize and scale up two specific methods: pyrolysis and gasification. Other methods are still in various stages of research and development.
- Pyrolysis decomposes plastics or other materials at moderately elevated temperatures in an oxygen-free or low-oxygen environment. In this environment, usually conducted at or above 500 ℃ (range 300-900 ℃), plastics undergo varying degrees of de-polymerization. This produces gas (called syngas), a pyrolysis oil that could potentially be further refined into fuels or chemicals, depending on its quality, and char.
- Gasification uses higher temperatures to convert plastics into gases, including nitrogen, carbon monoxide, hydrogen, and carbon dioxide, called syngas or producer gas. It may be preceded by pyrolysis. This also produces carbon char and hazardous air pollutants that must be trapped and disposed of. Syngas is used as a fuel as hydrogen and carbon monoxide can be combusted to provide heat to aid the gasification process.
Both pyrolysis and gasification require sorting a mixed plastic waste stream to remove polyvinyl chloride (PVC) and polyethylene terephthalate (PET), which can contaminate and degrade the final products and damage equipment.
New products, low-quality fuel, or waste?
The hope has been that the products of “advanced recycling” could be used to make new plastics, replacing some of the need for virgin fossil sources. Currently, however, most of what is produced is burned as low-value fuel or waste – not for producing new durable products – and therefore does not meet a basic criterion of “recycling” – converting materials into new, reusable products.
Thus, “advanced recycling” in its current form simply contributes to chemical pollution and diverts attention from the need to reduce plastic production.
It is also important to recognize that focusing on recycling and end-of-use without confronting the enormous actual and anticipated growth in plastic production will be hopelessly inadequate to confront the global plastic crisis under discussion in the UN Global Plastics Treaty negotiations.
To learn more about “advanced recycling,” see Schuyler Mitchell’s recent article in The Intercept, “Garbage In, Toxics Out: They Promised ‘Advanced Recycling’ for Plastics and Delivered Toxic Waste”; NRDC’s 2022 report, Recycling Lies: Chemical Recycling of Plastic is Just Greenwashing Incineration; and this recent webinar by the Halt the Harm network.
In addition, Beyond Plastics and the International Pollutants Elimination Network (IPEN) just released this valuable in-depth report on the issue: Chemical Recycling: A Dangerous Deception. (Also see their chemical recycling fact sheet.)
This is the first in a two-part series on so-called “advanced recycling” of plastics. Also see: “Advanced Recycling” of Plastics: Largely waste disposal by another name (Part 2).
This series is excerpted and condensed from a white paper written for Health Care Without Harm.
Ted Schettler, MD, MPH is Science Director for the Science and Environmental Health Network and a member of the CHE Advisory Team. He has worked extensively with community groups and non-governmental organizations throughout the US and internationally, addressing many aspects of human health and the environment, and has served on advisory committees of the US EPA and National Academy of Sciences. His publications include Generations at Risk: Reproductive Health and the Environment; In Harm's Way: Toxic Threats to Child Development; and Environmental Threats to Healthy Aging, as well as numerous articles in the medical literature.