Carbon dioxide Capturing Using Artificial Leaves

Engineers have constructed artificial leaves that can capture carbon dioxide 100 times better than current systems. Most other carbon capture systems only work with pure carbon dioxide from pressurized tanks. Artificial leaves, however, work in the real world. It captures carbon dioxide from more diluted sources, like air and flue gas produced by coal-fired power plants and combustion analysis lab and releases it for use as fuel and other materials.

Artificial leaf was developed in 2011 to mimic photosynthesis. It uses solar energy, water, and carbon dioxide to produce clean energy. But even the best artificial leaves only worked in the laboratory. They used pure, pressurized carbon dioxide from tanks. But in 2019, researchers from the University of Illinois at Chicago proposed a design solution that could bring artificial leaves out of the testing labs and into the environment. Their improved leaf, which would use carbon dioxide — a potent greenhouse gas — from the air, would be at least 10 times more efficient than natural leaves at converting carbon dioxide to fuel. More research can be done in a combustion analysis lab. 

Using the theoretical concept developed in 2019, the engineers modified a standard artificial leaf system. They used inexpensive material to introduce a water gradient, a dry side and a wet side, across an electrically charged membrane. On the dry side, an organic solvent attaches to available carbon dioxide and turns it into bicarbonate, which builds upon the membrane. As bicarbonate builds, these negatively charged ions are pulled across the membrane toward a positively charged electrode on the wet side of the membrane. On the wet side, the liquid solution dissolves the bicarbonate back into carbon dioxide, so it can be released and harnessed for fuel or other uses. Altering the electrical charge can speed up or slow down the rate of carbon capture. 

This “flux rate” is 100 times higher than existing systems. And very little energy was required to power the reactions, at 0.4 kilojoules per hour, less than what it takes to run a one-watt LED light bulb. The researchers say the system can capture carbon dioxide at $145 per ton. According to the  Department of Energy’s guidelines, these technologies should cost $200 per ton or less.

“Our artificial leaf system can be deployed outside the lab, where it has the potential to play a significant role in reducing greenhouse gasses in the atmosphere thanks to its high rate of carbon capture, relatively low cost and moderate energy, even when compared to the best lab-based systems,” said Meenesh Singh, assistant professor of chemical engineering in the UIC College of Engineering and corresponding author on the paper.

“It’s particularly exciting that this real-world application of an electrodialysis-driven artificial leaf had a high flux with a small, modular surface area,” Singh said. “This means that it has the potential to be stackable, the modules can be added or subtracted to more perfectly fit the need and affordably used in homes and classrooms, not just among profitable industrial organizations. A small module the size of a home humidifier can remove greater than 1 kg of CO2 per day, and four industrial electrodialysis stacks can capture greater than 300 kg of CO2 per hour from flue gas.”

Reference:

Aditya Prajapati, Rohan Sartape, Tomás Rojas, Naveen K. Dandu, Pratik Dhakal, Amey S. Thorat, Jiahan Xie, Ivan Bessa, Miguel T. Galante, Marcio H. S. Andrade, Robert T. Somich, Márcio V. Rebouças, Gus T. Hutras, Nathália Diniz, Anh T. Ngo, Jindal Shah, Meenesh R. Singh. Migration-assisted, moisture gradient process for ultrafast, continuous CO2 capture from dilute sources at ambient conditions. Energy & Environmental Science, 2022; DOI: 10.1039/D1EE03018C