Plastic products have been propelling our quality of life forward for over a century, from keeping food fresh longer to enhancing medical hygiene and making transportation more energy-efficient.
In the meantime, plastic waste has also accumulated. Today it is an unsolved and growing problem of gargantuan proportions. Worldwide, only 9 percent of plastic waste is recycled — largely through mechanical processing, creating products like drainage pipes — and 19 percent is incinerated. The rest is either buried in landfills or has escaped into the environment, where it damages ecosystems and harms human health.
To address existing and future plastic waste, new approaches beyond mechanical recycling are needed. Researchers have been studying chemical recycling, which converts the waste into new products by breaking the plastics down at the molecular level.
The concept of chemical recycling is controversial because it is used to describe many different processes, some of which may be worse for the environment than disposing the plastic waste in a landfill.
In 2023, a recycling center in Newaygo, Mich., announced plans to open a new chemical recycling facility in partnership with Clean-Seas, a subsidiary of Clean Vision Corp., a self-described clean-tech business.
When the project was announced, local journalists raised questions about what form of chemical recycling is planned, and whether it will be good for the community and environment. According to Clean-Seas’ press release, plastics will be converted into precursors for fuels.
As professors of chemistry who study chemical recycling, we think that making fuel from plastic waste is the wrong way to deal with this problem. Not only does it harm the climate and pollute air and water, but it’s also a stretch to even call it recycling.
An Air and Water Pollution Loophole
In late 2022, the Michigan Legislature passed an eight-bill package aimed at improving the statewide recycling rate of 23 percent for all types of waste.
A portion of these bills, which were contested by environmentalists and numerous lawmakers, redefined chemical recycling as manufacturing rather than waste management. Similar laws providing incentives for companies to invest in chemical recycling were recently passed in 24 other states, including Texas, Florida and Pennsylvania.
What may seem like a small distinction could have a big impact on how the proposed Newaygo facility would be regulated by the state. The facility would be allowed to release more pollution into the air and water if it is defined as a manufacturer rather than as a waste management facility.
Besides the air and water pollution implications, a more fundamental question is whether the Newaygo facility’s planned chemical recycling process — called pyrolysis — is the best use of this waste.
Pyrolysis involves heating waste plastics to break them down into a mixture of small molecules, typically hydrocarbons. The resulting “pyrolysis oil” is then sold on the commodity chemical marketplace, replacing oils derived from crude petroleum. The most commonly suggested use of pyrolysis oil is diesel or jet fuel, both of which generate greenhouse gases when burned.
Not all the waste will be converted to pyrolysis oils at Newaygo. According to Dan Bates, CEO of Clean-Seas’ parent company, half of the plastic fed into the Newaygo plant would be transformed into a complex mixture of light hydrocarbons, which would be burned on-site to provide energy to operate the plant.
If burning plastic-derived oils and gases doesn’t sound like recycling to you, the Michigan Legislature agrees, stating that “products sold as fuels are not recycled products.”
Given this legal distinction, it is unclear how the Newaygo facility can actually move forward with pyrolysis to produce fuels and still qualify as a chemical recycler.
Doubtful Benefits
So, will the chemical recycling practiced by Clean-Seas benefit western Michigan beyond the estimated 30 to 60 jobs it offers?
The main benefit of pyrolysis is supposed to be the diversion of plastic waste from landfills while producing fuels. The Newaygo facility aims to initially convert 50 tons per day, eventually growing to 500 tons per day.
The experience of other industrial pyrolysis projects casts doubt on these projections, with three ceasing operations in the past few months. Energy giant Shell walked back its pledge to pyrolyze a million tons of plastic waste per year because apparently there isn’t sufficient clean plastic waste available to use in the process.
Most waste plastic is too complex to be recycled. At every stage, from resin production to the manufacture of products, an assortment of molecules — often proprietary — are added to tailor the properties of plastics. During use, plastics are further contaminated with food waste and other nonplastic materials. Together, these impurities can lead to problems like reactor corrosion and the formation of contaminated outputs, which require inefficient separation steps.
Drawing conclusions about the climate impacts of chemical recycling can be challenging due to different underlying assumptions used in individual studies. However, a recent meta-analysis, which analyzed the results of 30 journal articles, concluded that using chemical recycling to make new plastics can benefit the climate by reducing greenhouse gas emissions — but that chemical recycling to produce fuels has the opposite effect.
So what should be done with plastic waste?
We believe both consumers and manufacturers should aim to keep materials in use for as long as possible, a standpoint articulated by the Ellen MacArthur Foundation in its report on rethinking the plastics life cycle.
Once all other uses for a plastic product have been exhausted, chemically recycling it to generate new plastic or other durable products can address the entangled problems of plastic waste and climate change.
If the output of the Newaygo pyrolysis facility was new plastics, this circular approach would be better for the climate. But recycling plastics for fuel will not.
Anne McNeil is a professor of chemistry and macromolecular science and engineering at the University of Michigan. Aleksandr V. Zhukhovitskiy is a professor of chemistry at the University of North Carolina, Chapel Hill. Yutan Getzler is the Pamela G. Hollie Professor of Chemistry at Kenyon College. This commentary is republished from The Conversation under a Creative Commons license. Read the original article.
Governing’s opinion columns reflect the views of their authors and not necessarily those of Governing’s editors or management
