Fuel for the future

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Ulsan National Institute of Science and Technology (UNIST) and Georgia Tech have developed a new system that absorbs CO2 and produces electricity and useable hydrogen fuel.

The new device, which the team calls a Hybrid Na-CO2 System, is basically a big liquid battery. A sodium metal anode is placed in an organic electrolyte, while the cathode is contained in an aqueous solution. The two liquids are separated by a sodium super ionic conductor membrane.

When CO2 is injected into the aqueous electrolyte, it reacts with the cathode, turning the solution more acidic, which in turn generates electricity and creates hydrogen. In tests, the team reported a CO2 conversion efficiency of 50%, and the system was stable enough to run for over 1,000 hours without causing any damage to the electrodes. Unlike other designs, it doesn’t release any CO2 as a gas during normal operation – instead, the remaining half of the CO2 was recovered from the electrolyte as plain old baking soda.

“Carbon capture, utilisation, and sequestration (CCUS) technologies have recently received a great deal of attention for providing a pathway in dealing with global climate change,” says Professor Guntae Kim, head of the study. “The key to that technology is the easy conversion of chemically stable CO2 molecules to other materials. Our new system has solved this problem with CO2 dissolution mechanism.”

The team plans to continue improvement on the design.

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