Researchers make plastic from garbage

Researchers from Sweden’s Chalmers University of Technology have developed a circular economy technique that sees mixed waste converted into raw carbon atoms to be used in the production of plastic.

Mixed waste usually ends up in landfills or being incinerated. The Swedish scientists were looking to develop a technology that could utilise molecules in plastic, paper, wood and food waste, all of which are full of useful carbon atoms that otherwise go unused.

“There are enough carbon atoms in waste to meet the needs of all global plastic production. Using these atoms, we can decouple new plastic products from the supply of virgin fossil raw materials,” said Henrik Thunman, Professor of Energy Technology at Chalmers and one of the authors of the new study.

“If the process is powered by renewable energy, we also get plastic products with more than 95% lower climate impact than those produced today, which effectively means negative emissions for the entire system.”

Plastic recycling is generally inefficient and only reclaims a relatively small amount of material for further use. The advanced recycling method proposed by the researchers uses thermochemical technologies and sees waste being heated to 600–800°C to convert it to gas, after which hydrogen is added to subsequently produce plastic.

“The key to more extensive recycling is to look at residual waste in a whole new way: as a raw material full of useful carbon atoms. The waste then acquires value, and you can create economic structures to collect and use the material as a raw material worldwide,” said Thunman.

The researchers were inspired by the natural carbon cycle, whereby plants absorb CO₂ for nutrients and then release it back into the atmosphere when they die, where it is used again to grow more plants in the future.

“However, our technology differs from the way it works in nature because we don’t have to take the detour via the atmosphere to circulate the carbon in the form of carbon dioxide. All the carbon atoms we need for our plastic production can be found in our waste, and can be recycled using heat and electricity,” said Thunman.

The researchers suggest that renewable energy can be used to power this advanced recycling process, which would be more energy efficient that currently used methods for disposing of mixed waste. Unused heat from the process could be harvested for use elsewhere too.

The research was carried out as part of the FUTNERC project, which is helping the chemical industry reduce greenhouse gas emissions. The processes have been tested through collaboration with a plastic manufacturer, Borealis.

“Our goal is to create a circular economy for plastics,” said Anders Fröberg, CEO of Borealis. “Our plastic products are key to the transformation to a sustainable society, so it’s important for us to support research like this. We already have projects that create circularity for our plastic products, but more solutions are needed. Therefore, we are pleased with these excellent results, which can help bring us a step closer to our goal.”

The study describing the technique was published in the Journal of Cleaner Production.

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