Solar-powered reactor converts CO2 into clean fuels

Scientists at the University of Cambridge have made significant progress in the field of carbon capture and utilization, showcasing a solar-powered reactor that can convert carbon dioxide (CO2) from industrial processes or directly from the air into clean, sustainable fuels. The researchers have successfully transformed captured CO2 and plastic waste into syngas, a vital component for sustainable liquid fuels, and glycolic acid, widely used in the cosmetics industry.

Unlike previous experiments, this study used real-world sources of CO2, such as industrial exhaust or atmospheric CO2. The team effectively captured and concentrated CO2, converting it into sustainable fuels. Although further advancements are necessary before this technology can be employed on an industrial scale, the results published in the journal Joule signify a noteworthy stride towards producing clean fuels without relying on environmentally harmful oil and gas extraction.

Professor Erwin Reisner’s research group, located in the Yusuf Hamied Department of Chemistry, has been at the forefront of developing sustainable fuels that are carbon-neutral, drawing inspiration from photosynthesis in plants. Their artificial leaves mimic the process of photosynthesis by harnessing solar energy to convert CO2 and water into fuels.

While the previous solar-driven experiments utilized pure and concentrated CO2 from a cylinder, the researchers recognized the need to actively capture CO2 from industrial processes or the atmosphere for practical application. However, since CO2 exists alongside various other molecules in the air, selectively targeting and converting highly diluted CO2 poses a significant technical challenge.

Professor Reisner emphasizes that the goal extends beyond decarbonization to de-fossilization, aiming to eliminate fossil fuels entirely and establish a circular economy. In the short term, this technology could aid in carbon emissions reduction by capturing CO2 from industrial sources and transforming it into valuable products. Ultimately, the objective is to capture CO2 directly from the air, cutting fossil fuel usage out of the equation and paving the way for carbon capture and utilization as a viable alternative to carbon capture and storage. Unlike the latter, which involves burying CO2 underground with uncertain long-term consequences, carbon capture and utilization can generate useful products from CO2, simultaneously mitigating its environmental impact.

The researchers have successfully modified their solar-driven technology to operate with flue gas or directly from the air, utilizing the sun’s energy to convert CO2 and plastics into fuels and chemicals.

To selectively capture CO2 from the air, the researchers devised a system where air is passed through an alkaline solution. The CO2 becomes trapped in the solution while other gases, such as nitrogen and oxygen, are safely released. This process enables the researchers to concentrate the captured CO2, facilitating its conversion.

The integrated system consists of a photocathode and an anode, with two compartments. In one compartment, the captured CO2 solution is transformed into syngas, a basic fuel. In the other compartment, plastics are converted into valuable chemicals solely using sunlight.

One of the researchers, Dr. Motiar Rahaman, highlights the significance of incorporating plastics into the system, as it aids the conversion of CO2 from the air. The plastics donate electrons to the CO2, resulting in the breakdown of plastics into glycolic acid, a sought-after compound in the cosmetics industry, while the CO2 is converted into syngas.

Dr. Sayan Kar, another co-first author of the study, emphasizes the potential of this solar-powered system to transform two harmful waste products, plastic and carbon emissions, into useful resources. By capturing CO2 from the air and producing clean fuel, the researchers aim to eliminate the involvement of the fossil fuel industry in fuel production, thereby mitigating the risks associated with climate change.

The researchers are currently focused on developing an improved bench-top demonstrator device that enhances efficiency and practicality. This device aims to showcase the advantages of combining direct air capture with CO2 utilization as a viable path towards achieving a zero-carbon future.

Source: University of Cambridge

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