According to Prof Erwin Reisner, plastic waste dumps could be a valuable source of energy in the future. He states that plastic is rich in energy and chemical composition that can be unlocked.
However, due to the durability of plastic, less than 10% of the seven billion tonnes created has been recycled. The Ellen MacArthur Foundation’s plastics programme manager, Dilyana Mihaylova, adds that our take-make-waste economy results in the loss of billions of dollars worth of valuable materials.
Globally, the production of plastic exceeds 400 million tonnes annually, equivalent to the weight of the entire human population. Unfortunately, approximately 85% of this plastic ends up in landfills or the environment, where it will remain for hundreds or thousands of years. Efforts are now being made to discover the most effective method of breaking down the chemical bonds in plastic and retrieving the Earth’s valuable resources trapped within.
Although mechanical recycling involves washing, shredding, melting, and reforming waste plastic, the plastic degrades over time and the resulting products are often of inconsistent quality.
The plastics industry favors chemical recycling, a process that uses additives to modify the chemical composition of waste plastic, transforming it into substances that can be utilized as raw materials, potentially even for creating fuel like gasoline and diesel.
However, this approach is currently expensive and inefficient and has received criticism from environmental organizations. As Ms. Mihaylova puts it, “Just as we can’t recycle our way out of the plastics pollution crisis, we can’t rely on plastics-to-fuel processes to solve the problem either.” Could a new solar-powered system offer a solution?
Prof Reisner and his team have developed a solar-powered process that can convert two waste streams – plastic and CO2 – into two chemical products simultaneously. This technology can transform plastic and CO2 into syngas and glycolic acid, which is used in the cosmetics industry.
The process involves integrating catalysts, chemical compounds that speed up a chemical reaction, into a light absorber. The reaction occurs automatically when exposed to sunlight, with no need for additional energy, and it operates at room temperature and pressure.
Additionally, it produces no harmful waste. Prof Reisner says that while other solar-powered technologies show promise in addressing plastic pollution and CO2 conversion, his process is the first to combine both in a single system.
By combining both, the process adds value and creates four value streams: mitigation of plastic waste, mitigation of CO2, and the production of two valuable chemicals. He hopes that this development will bring them closer to commercialisation. Furthermore, the system can handle plastic waste that is otherwise unrecyclable.
According to Professor Reisner, plastic contaminated with food waste is usually sent for incineration, but this type of plastic is actually beneficial for their process. “Food is a good substrate – so it makes our process work better,” he says.
Scientists worldwide are exploring ways to repurpose plastic waste.
When plastics are broken down, their components can be reassembled into a wide range of new products, including detergents, lubricants, paints and solvents, as well as biodegradable compounds used in biomedical applications.
Nature has already developed methods for breaking down polymers – which are large molecules made up of repeating units – and plastic is a type of synthetic polymer.
