Carbon dioxide from industrial processes or directly from the air can be captured and converted into clean, sustainable fuels using only solar energy. Researchers at the University of Cambridge have demonstrated a solar-powered reactor that turns captured CO2 and plastic waste into usable fuels and valuable chemicals.
In experiments, CO2 was transformed into synthesis gas, a key component for sustainable liquid fuels and plastic bottles, and into glycolic acid, a common ingredient in cosmetics.
The major advancement over earlier work is that the Cambridge team sourced CO2 from real-world environments—industrial discharges and ambient air—rather than relying on concentrated cylinders. They succeeded in capturing, concentrating, and converting CO2 into a renewable fuel source.
While scaling this technology for industrial use still requires further development, the results published in the journal Joule represent a meaningful step toward clean fuel production. The researchers note that the approach could stimulate the economy while reducing dependence on environmentally damaging oil and gas extraction.
Professor Erwin Reisner and his research group from Yusuf Hamied’s Department of Chemistry have been pursuing sustainable net-zero carbon fuels inspired by photosynthesis. Their work centers on artificial leaves that convert CO2 and water into fuel using only solar energy.
To date, solar-powered experiments have used pure, concentrated CO2 from cylinders. Practical use requires the ability to actively capture CO2 from industrial processes or directly from the air.
Decarbonization and defossification
The air contains many different molecules, so a core technical challenge is making the process selective for CO2 at very low concentrations.
Reisner emphasizes that decarbonization must go beyond mere decarbonization and toward defossification: to create a truly circular economy, fossil fuels must be phased out entirely. In the medium term, the technology could reduce emissions by capturing CO2 from industry and converting it into useful products, but the ultimate goal is to remove fossil fuels from the energy system and keep CO2 in the atmosphere. [Citation: Cambridge University]
The team has drawn inspiration from carbon capture and storage (CCS), a widely discussed approach that captures CO2 and stores it underground. Reisner notes that rather than burying carbon, capturing and using it can deliver tangible benefits while avoiding long-term underground CO2 concerns. [Citation: Joule]
The researchers adapted their technology to operate with combustion gases or directly from air, using only sunlight to convert CO2 and plastic into fuel and chemicals.
In the process, air is bubbled through an alkaline solution to selectively capture CO2 while harmlessly releasing nitrogen and oxygen. This concentration step makes it easier to work with CO2 present in ambient air. [Citation: Cambridge University]
Toward a zero-carbon future
The integrated system features a photocathode and a photoanode arranged in two chambers. In one chamber, CO2-rich solution is captured and converted into synthesis gas, while plastics are converted into useful chemicals using solar energy alone.
Researchers highlight the plastic component as a crucial element: breaking down plastic waste donates electrons to the CO2 reduction process, producing glycolic acid and, alongside, CO2-derived synthesis gas. Glycolic acid is widely used in cosmetics. [Citation: study authors]
This solar-powered setup takes two problematic waste streams—plastic and carbon emissions—and converts them into valuable outputs. The study notes that combining plastic waste with direct air capture of CO2 makes the chemistry more feasible and impactful. [Citation: Joule]
Instead of storing CO2 underground as in CCS, the approach aims to pull CO2 from the air and turn it into clean fuel, potentially reducing reliance on fossil fuels in fuel production. [Citation: Cambridge University]
Experts emphasize that turning CO2 from the air into something useful is a meaningful achievement, especially when powered solely by sunlight. Researchers are working on a desktop demonstration device with improved efficiency and practicality to showcase the benefits of combining direct air capture with CO2 conversion. [Citation: Cambridge University]
Reference report: Joule journal, S2542-4351(23)00219-2.
Further work continues to refine the system and demonstrate practical applications for a zero-carbon future. [Citation: Cambridge University]