Most separation methods remove CO2 from flue gas by using special liquid scrubbers, which are subsequently heated to release the gas. Although the process is effective, it also consumes large amounts of energy. Researchers at CT and MIT have therefore come up with an idea for removing CO2 from flue gas by electrochemical means. This is done by using negatively charged functionalized quinone molecules that selectively combine with CO2. The bound CO2 is released again when the molecular ion is discharged at a counter-electrode. To remove the CO2 from the flue gas, the process is conducted at a constant temperature by electrochemical cells that separate the flue gas channels from the channels that collect the CO2. The new approach could reduce the amount of energy needed to remove the CO2 by 50 to 75 percent. Researchers at MIT are developing the chemical compounds that can selectively absorb the CO2, while scientists at Siemens Corporate Technology specialize in creating associated electrical structures. The project is benefiting from the CT researchers’ many years of experience in developing electrodes with large interaction surfaces for use in fuel cells. The researchers want to construct special cells for the quinones, in which the electrochemical processes would be carried out. They want to use the property of quinones to store or release CO2 depending on their electrical charge and the fact that the charge and discharge can be controlled by means of an electric current.

The new method for removing CO2 is not expected to be ready for commercial use before 2020. Scientists at MIT are conducting in-depth computer simulations in order to find the right chemical compounds to utilize for the process. At the same time, researchers at CT are working on electrode concepts for ensuring optimal contact between the electrodes, the absorbing substance, and the flue gas. The fact that the U.S. Department of Energy will be funding the project in coming years shows that the approach is very promising.