University of Cambridge researchers have developed a solar energy powered system that can transform plastic waste and greenhouse gases into sustainable fuels and other valuable products.

The system can convert two waste streams into two chemical products at the same time. Its likely to be the first time this has been achieved in a solar-powered reactor.

Simplified diagram of a solar PEC reactor. Image Credit: University of Cambridge. Click the study paper link for more images and information.

The team’s study results have been published in the journal Nature Synthesis.

The reactor converts the carbon dioxide (CO2) and plastics into different products that are useful in a range of industries. In tests, CO2 was converted into syngas, a key building block for sustainable liquid fuels, and plastic bottles were converted into glycolic acid, which is widely used in the cosmetics industry. The system can easily be tuned to produce different products by changing the type of catalyst used in the reactor.

Converting plastics and greenhouse gases – said to be two of the biggest threats facing the natural world – into useful and valuable products using solar energy is an important step in the transition to a more sustainable, circular economy.

Professor Erwin Reisner from the Yusuf Hamied Department of Chemistry, the paper’s senior author said, “Converting waste into something useful using solar energy is a major goal of our research. Plastic pollution is a huge problem worldwide, and often, many of the plastics we throw into recycling bins are incinerated or end up in landfill.”

Reisner also leads the Cambridge Circular Plastics Centre (CirPlas), which aims to eliminate plastic waste by combining blue-sky thinking with practical measures.

Other solar-powered ‘recycling’ technologies hold promise for addressing plastic pollution and for reducing the amount of greenhouse gases in the atmosphere, but to date, they have not been combined in a single process.

Subhajit Bhattacharjee, the paper’s co-first author said, “A solar-driven technology that could help to address plastic pollution and greenhouse gases at the same time could be a game-changer in the development of a circular economy.”

Co-first author Dr Motiar Rahaman said, “We also need something that’s tuneable, so that you can easily make changes depending on the final product you want.”

The researchers developed an integrated reactor with two separate compartments: one for plastic, and one for greenhouse gases. The reactor uses a light absorber based on perovskite – a promising alternative to silicon for next-generation solar cells.

The team designed different catalysts, which were integrated into the light absorber. By changing the catalyst, the researchers could then change the end product. Tests of the reactor under normal temperature and pressure conditions showed that the reactor could efficiently convert PET plastic bottles and CO2 into different carbon-based fuels such as CO, syngas or formate, in addition to glycolic acid. The Cambridge-developed reactor produced these products at a rate that is also much higher than conventional photocatalytic CO2 reduction processes.

Rahaman explained, “Generally, CO2 conversion requires a lot of energy, but with our system, basically you just shine a light at it, and it starts converting harmful products into something useful and sustainable. Prior to this system, we didn’t have anything that could make high-value products selectively and efficiently.”

Bhattacharjee noted, “What’s so special about this system is the versatility and tuneability – we’re making fairly simple carbon-based molecules right now, but in future, we could be able to tune the system to make far more complex products, just by changing the catalyst.”

Reisner recently received new funding from the European Research Council to help the development of their solar-powered reactor. Over the next five years, they hope to further develop the reactor to produce more complex molecules. The researchers say that similar techniques could someday be used to develop an entirely solar-powered recycling plant.

“Developing a circular economy, where we make useful things from waste instead of throwing it into landfill, is vital if we’re going to meaningfully address the climate crisis and protect the natural world,” said Reisner. “And powering these solutions using the Sun means that we’re doing it cleanly and sustainably.”

The research was supported in part by the European Union, the European Research Council, the Cambridge Trust, Hermann and Marianne Straniak Stiftung, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI). Erwin Reisner is a Fellow of St John’s College, Cambridge.


Looks like a really good idea has come to fruition. One does hope so.

Yet the details are really thin. They’re not saying in the press release how much solar power is needed nor describing the capacities that might be forthcoming. What other information might be available is behind the paywall.

Yet there is some hope that such a system could be affordable. It would be nice if a home sized unit would replace the recycling bin for plastics. One might really be making a contribution in real substance rather than, as many perceive, simply being inconvenienced.


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