Researchers from the University of Cambridge have made significant progress in developing a solar-powered reactor that can convert captured CO2 and plastic waste into sustainable fuels and valuable chemical products. The team successfully transformed CO2 into syngas, a crucial component for sustainable liquid fuels, while plastic bottles were converted into glycolic acid, commonly used in the cosmetics industry.
Unlike previous tests, where concentrated CO2 was used, the researchers obtained CO2 from real-world sources like industrial exhaust and ambient air. They captured and concentrated the CO2, successfully converting it into sustainable fuel.
Although further improvements are necessary before the technology can be implemented on an industrial scale, the results, published in the journal Joule, represent a significant step towards producing clean fuels that can power the economy without relying on environmentally damaging oil and gas extraction.
Led by Professor Erwin Reisner’s research group, the team has been working on developing sustainable, net-zero carbon fuels inspired by photosynthesis. Their artificial leaves mimic the process of plants converting sunlight and CO2 into food, utilizing solar energy to convert CO2 and water into fuels.
In their previous experiments, they used concentrated CO2 from cylinders, but for practical application, the technology needs to actively capture CO2 from industrial processes or directly from the air. Selectively converting highly diluted CO2 from the air poses a major technical challenge due to the presence of various molecules.
The researchers aim not only for decarbonization but also for de-fossilization, seeking to eliminate the use of fossil fuels and create a truly circular economy. They envision a future where carbon emissions are captured from industries and transformed into useful products, while also capturing CO2 directly from the air.
The team drew inspiration from carbon capture and storage (CCS), a method used to capture CO2 and store it underground. However, instead of storage, they propose carbon capture and utilization (CCU) to convert CO2 into useful substances, eliminating the need for fossil fuels.
Adapting their solar-driven technology, the researchers designed a system that can utilize flue gas or air to convert CO2 and plastics into fuel and chemicals using solar energy alone. By bubbling air through an alkaline solution, CO2 is selectively trapped while other gases like nitrogen and oxygen are released harmlessly. This process enables the concentration of CO2 from the air, facilitating further processing.
The integrated system consists of a photocathode and an anode, with two compartments. In one, the captured CO2 solution is converted into syngas, a simple fuel. In the other, plastics are converted into useful chemicals using sunlight.
The addition of plastic waste to the system plays a crucial role. The plastic donates electrons to CO2, resulting in its breakdown into glycolic acid, a valuable compound widely used in cosmetics, while the CO2 is converted into syngas.
The researchers highlight the significance of their solar-powered system, which can convert two harmful waste products, plastic and carbon emissions, into valuable resources. By capturing CO2 from the air and producing clean fuel, they aim to reduce the reliance on the fossil fuel industry, contributing to efforts in avoiding climate destruction.
The team is currently working on a bench-top demonstrator device with improved efficiency and practicality to demonstrate the benefits of combining direct air capture with CO2 utilization, paving the way towards a zero-carbon future.