Currently, only a small portion of the material that could be recycled into new plastic is recycled. Chalmers University of Technology in Sweden has recently proved how carbon atoms in mixed garbage can replace all fossil raw materials in the manufacturing of new plastic. The recycling process is based on the natural carbon cycle and has the potential to reduce the climate impact of plastic products while also cleaning the air of carbon dioxide.
“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. 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,” says Henrik Thunman, Professor of Energy Technology at Chalmers University of Technology and one of the authors of the study published in the Journal of Cleaner Production.
To establish circular cycles, we must make greater use of the resources that are already available in society. Henrik Thunman and his research team aim to focus on a critical resource that is frequently wasted today: the carbon atoms in our waste, which are currently burnt or disposed of in landfills rather than recycled. This is made possible by technologies that target the carbon in plastic, paper, and wood wastes, with or without food residues, to provide a raw material for the creation of polymers with the same range and quality as those currently produced from fossil raw materials.
Similar to nature
Current plastic recycling processes can only replace about 15-20% of the fossil raw material required to supply society’s need for plastic. The researchers’ improved approaches are based on thermochemical technology and entail heating the trash to 600-800 degrees Celsius. The waste is subsequently converted into a gas, which, when combined with hydrogen, can replace the building blocks of plastics. Using this recycling technology could decouple the supply of new fossil raw materials from the supply of new plastic products.
The study’s researchers are working on a thermochemical recycling approach that creates a gas that can subsequently be used as a raw material in the same plants where plastic products are currently created from fossil oil or gas. At the Chalmers Power Central, various forms of waste, such as old plastic items and paper cups with or without food residues, are fed into the reactors.
“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,” says Henrik Thunman.
The process’s premise is based on the natural carbon cycle. When plants wither, they are broken down into carbon dioxide, and carbon dioxide, using the sun as an energy source and photosynthesis, makes new plants.
“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,” says Henrik Thunman.
The researchers’ calculations show that the energy to power such processes can be taken from renewable sources such as solar, wind or hydro power or by burning biomass, and they will be more energy-efficient than the systems in use today. It is also possible to extract excess heat from recycling processes, which in a circular system would compensate for the heat production currently derived from waste incineration, while eliminating the carbon dioxide emissions associated with energy recovery.
Can replace fossil raw materials
The research has been carried out as part of the FUTNERC* project. The researchers have proven that the process can work in collaboration with plastics manufacturer Borealis in Stenungsund, Sweden, where they have verified the results and shown that the raw material can be used to make plastic, replacing the fossil raw materials used today.
“Our goal is to create a circular economy for plastics. 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,” says Anders Fröberg, CEO of Borealis AB.
The study Co-recycling of natural and synthetic carbon materials for a sustainable circular economy was published in the Journal of Cleaner Production and was written by Isabel Cañete Vela,Teresa Berdugo Vilches, Göran Berndes, Filip Johnsson and Henrik Thunman.
The researchers are active at Chalmers University of Technology.