TECHNOLOGY

A French company is using enzymes to recycle the most common single-use plastics


Since single-use plastics are primarily derived from petroleum, plastics could account for 20% of the world’s annual oil consumption by 2050. Reducing our reliance on plastics, and finding ways to reuse plastics that already exist in the world, can greatly reduce emissions.

At the moment, only 15% of all plastics worldwide are collected for recycling each year. Researchers have been trying since the 1990s to find new ways to break down plastics in hopes of further reusing them. Companies and researchers have worked to create enzymatic processes, such as those used in carbios, as well as chemical processes, such as those used by loop industries. But only recently have enzymatic and chemical processes begun to become commercial.

The new Carbios reactor measures 20 cubic meters – close to the size of a cargo van. It can hold the equivalent of two metric tons of plastic or about 100,000 ground-up bottles at a time and can break down building blocks of PET-ethylene glycol and terephthalic acid in 10 to 16 hours.

The company plans to use what it has learned from the exhibition facility to build its first industrial plant, which will have a furnace about 20 times larger than the exhibition furnace. Allen Marty, Carbios’ chief science officer, said the full-scale plant would be built by a plastic manufacturer somewhere in Europe or the United States and would be operational by 2025.

Since the company was founded in 2011, Carbios has been developing enzymatic recycling. Its process for cutting long chains of polymer made of plastic depends on enzymes. The resulting monomers can be refined and tied together to form new plastics. Researchers at Carbios began to break down the leaves with a natural enzyme used by bacteria, then broke down the PET and tweaked it to make it more efficient.

Carbios exhibition facility in Claremont-Ferrand, France. Photo courtesy Scottprod.

Carbios estimates that its enzymatic recycling process reduces greenhouse gas emissions by about 30% compared to virgin PET. Marty says he hopes that number will increase because they work kinks.

In a recent report, researchers estimated that making PET from enzymatic recycling could reduce greenhouse gas emissions by 17% to 43% compared to making virgin PET. According to Greg Beckham, a researcher at the U.S. National Renewable Energy Laboratory and co-author of the report, the report isn’t specifically about carbios, but it’s probably a good guess for its process.

While creating new enzymes was a major focus of new research and commercial efforts, other parts of the process will determine how efficient and cost-effective the technology will be, Beckham said, leading a consortium on new plastics recycling and production methods.

“It’s all a less glamorous thing,” Beckham said, like turning plastic into a form that can effectively break down enzymes or separate enzymes that fall apart, which can take a lot of energy and time, and increase emissions and costs.



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