Carbon dioxide can be drawn from industrial streams or captured directly from the air and then transformed into clean, sustainable fuels using only solar energy. This concept has been demonstrated by researchers at the University of Cambridge, who built a solar powered reactor that converts captured CO2 and plastic waste into fuels and valuable chemicals.
In the tests, the process produces synthesis gas, a key precursor for sustainable liquid fuels. It also creates glycolic acid, a widely used ingredient in cosmetics. The British team sourced CO2 from realistic, real world sources such as industrial waste streams and the open air, rather than relying on concentrated cylinders. They were able to capture and concentrate CO2 and convert it into useful fuels and chemicals.
While further improvements are needed before scaling up to industry, the results published in the journal Joule show a significant step toward clean fuel production. The researchers describe their work as a move toward stimulating the economy without the environmental costs of oil and gas extraction.
The research group led by Professor Erwin Reisner has spent years exploring sustainable net-zero carbon fuels inspired by photosynthesis. They are developing artificial leaves that convert CO2 and water into fuels using solar energy.
An artificial leaf picture caption shows the photoanode side. Motiar Rahaman / University of Cambridge
Until now, these solar powered experiments relied on pure, concentrated CO2 from cylinders. For practical use, the technology must be able to actively capture CO2 from industrial processes or directly from the air.
Decarbonization and defossilization
The challenge is that CO2 is only one of many molecules present in air, so the system must be selective enough to convert the highly diluted CO2.
Reisner emphasizes that the aim is not only decarbonization but also defossilization: creating a truly circular economy requires replacing fossil fuels entirely.
In the medium term, this approach could help reduce carbon emissions by removing them from industry and turning them into useful products. In the long term, the goal is to remove fossil fuels from the equation completely and to capture CO2 from the air.
Researchers note that carbon capture and storage, or CCS, involves capturing CO2, pumping it underground, and storing it. CCS has been popular among the fossil fuel sector as a strategy to reduce emissions through oil and gas exploration.
But instead of storing carbon, the aim is to capture and use it. If carbon can be harnessed to make something valuable rather than buried, the long‑term consequences of fossil fuels could be avoided.
An additional photograph caption shows a photoreactor with artificial leaves operating under solar radiation. Ariffin Mohamad Annuar / University of Cambridge
The researchers also adapted the technology to work with combustion gases or air, turning CO2 and plastic into fuel and chemicals with only sunlight as the energy input.
By passing air bubbles through a solution that contains an alkaline component, CO2 can be selectively retained while other gases such as nitrogen and oxygen are harmlessly separated. This concentration step makes the capture of CO2 from the air easier, according to the University of Cambridge.
Toward a carbon free future
The system includes a photocathode and a photoanode in two chambers. In one chamber, CO2 is captured and converted into syngas, a simple fuel. In the other, plastics are converted into useful chemicals using only sunlight.
The plastic component is described as a key trick for the system. Capturing and using CO2 from the air makes the chemistry more challenging, but adding plastic waste helps donate electrons to CO2. Plastic breaks down into glycolic acid, widely used in cosmetics, while CO2 becomes syngas, a simple fuel.
One study co-author notes that this solar powered setup turns two harmful waste streams, plastic and carbon emissions, into something genuinely useful. Sayan Kar, another co-author, echoes the sentiment that the work demonstrates a meaningful path forward.
Another photo caption shows plastic bottles for recycling. Pixabay
Rather than storing CO2 underground as in CCS, the researchers aim to capture it from the air and produce clean fuel. This approach could help reduce the role of the fossil fuel industry in fuel production and, potentially, limit climate disruption.
The team expresses pride in the fact that CO2 can be drawn from the air and turned into something valuable using just sunlight. The researchers also note the ongoing work on a benchtop demonstration device to improve efficiency and practicality, highlighting the benefits of combining direct air capture with CO2 utilization.
Reference report: Joule, 2023 study reported by the researchers. [Citation: Joule, 2023, study on solar powered CO2 conversion]
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