A French company uses enzymes to recycle one of the most common single-use plastics

Because single-use plastics are largely derived from petroleum, plastics could account for 20% of the world’s annual oil consumption by 2050. Reducing our dependence on plastics and finding ways to reuse the plastic that is already in the world could significantly reduce emissions.

Currently, only around 15% of all plastics worldwide are collected for recycling annually. Since the 1990s, researchers have been trying to find new ways to break down plastic in hopes of recycling more of it. Companies and researchers have worked to develop enzymatic processes such as those used at Carbios, as well as chemical processes such as the Loop Industries method. But it is only recently that enzymatic and chemical processes have started to become commercial.

The new reactor from Carbios measures 20 cubic meters – about the size of a transporter. It can hold two tons of plastic or the equivalent of around 100,000 ground bottles at the same time and break it down into the building blocks PET – ethylene glycol and terephthalic acid – in 10 to 16 hours.

The company plans to use the findings from the demonstration plant to build its first industrial facility, which will house a reactor roughly 20 times larger than the demonstration reactor. This large-scale facility is being built near a plastics manufacturer somewhere in Europe or the US and is expected to be operational by 2025, says Alain Marty, Chief Science Officer of Carbios.

Carbios has been developing enzymatic recycling since the company was founded in 2011. The process relies on enzymes to break down the long polymer chains that make up plastic. The resulting monomers can then be purified and combined into new plastics. Carbios researchers started with a natural enzyme used by bacteria to break down leaves and then tweaked it to make it more efficient at breaking down PET.

The Carbios demonstration plant in Clermont-Ferrand, France. Image courtesy of SkotchProd.

Carbios estimates that its enzymatic recycling process reduces greenhouse gas emissions by around 30% compared to pure PET. Marty says he expects that number to go up once the kinks are fixed.

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. The report didn’t specifically look at Carbios, but it’s likely a good estimate for its process, according to Gregg Beckham, a researcher at the US National Renewable Energy Laboratory and co-author of the report.

While developing new enzymes has been a major focus of new research and commercial endeavors, other parts of the process will determine how efficient and inexpensive the technology will be, says Beckham, who leads a consortium on new plastic recycling and production methods.

“It’s all less glamorous,” says Beckham, like putting the plastic into a form that the enzymes can efficiently break down or separating what the enzymes spit out can be a lot of energy and time, and emissions and costs soaring to drive .