Engineers at the University of Illinois Chicago have developed a low-cost artificial leaf that can capture carbon dioxide 100 times more efficiently than current systems. This artificial leaf works in the real environment, unlike other carbon capture systems that work in labs using pure carbon dioxide from pressure tanks. It takes carbon dioxide from more diluted sources, such as air and flue gas from coal-fired power plants, and converts it into fuel and other products.
Meenesh Singh, assistant professor of chemical engineering in the UIC College of Engineering said, “Our artificial leaf system can be deployed outside the lab, where it has the potential to play an important role in decreasing greenhouse gases in the air based on the high rate of carbon capture, relatively low cost, and moderate energy.”
The scientists developed a basic artificial leaf system with affordable materials to integrate a water gradient, including a dry side and a wet side, over an electrically charged membrane, based on a previously published theoretical notion.
On the dry side, an organic solvent binds to carbon dioxide, resulting in a bicarbonate (baking soda) concentration on the membrane. When bicarbonate builds up, these negatively charged ions are drawn across the membrane toward a positively charged electrode in a water-based solution on the membrane's wet side. The bicarbonate in the liquid solution dissolves back into concentrated carbon dioxide, which can then be discharged and used for fuel or other purposes.
UIC scientists discovered in the test that the device, despite its small size, had a very high flux of 3.3 millimoles per hour per 4 square centimeters, which is a rate of carbon capture compared to the surface area required for the reactions. Even while only a small amount of electricity (0.4 KJ/hour) was required to power the reaction, it outperformed rival systems by more than 100 times, using less energy than a 1-watt LED lightbulb. The cost, according to their calculation, is at US$145 per ton of carbon dioxide, which is in accordance with Department of Energy recommendations that the cost should not exceed US$200 per ton.
Singh added, “it's really fascinating that this real-world use of an electrodialysis-driven artificial leaf had a high flux with a small, modular surface area. This means it can be stacked, the modules may be added or subtracted to better match the requirement, and it can be utilized economically in homes and classrooms, not just among industrial groups. A small module the size of a household humidifier may remove more than 1 kilogram of carbon dioxide every day, while four industrial electrodialysis stacks can capture more than 300 kilos of carbon dioxide per hour from flue gas.”
