In this diagram of the new system, air entering from top right passes to one of two chambers (the gray rectangular structures) containing battery electrodes that attract the carbon dioxide. Then the airflow is switched to the other chamber, while the accumulated carbon dioxide in the first chamber is flushed into a separate storage tank (at right). These alternating flows allow for continuous operation of the two-step process.
Carbon dioxide (CO2) is a chemical compound that is released into the planet’s atmosphere through the combustion of fossil fuels, our own respiration, volcanoes, microorganism fermentation, and more. The problem with CO2 is that it is a greenhouse gas, which means that it contributes to the rising of the median temperatures on Earth.
While we have plants that use in the context of their photosynthesis, we are depositing it into the atmosphere at higher rates that the existing plants can convert it to energy. This creates a need for a CO2 removal system, and MIT has developed exactly that.
What MIT’s device is, is essentially a battery that captures CO2 from the stream of the air that is passing over its electrodes during charging. When the battery discharges, the CO2 is passed inside a storage tank. This is happening thanks to a chemical reaction that is taking place at the molecular level. More specifically, the negative electrode is coated with polyanthraquinone, a polymer that captures CO2 molecules. The electrodes show high affinity for CO2 when the battery is charging, and no affinity at all when discharging.
The question that underpins the feasibility of this battery is its longevity, and the MIT researchers have promising news on that front too. As they report, the battery can withstand 7000 charging and discharging cycles with a performance loss at this point being only 30%. As for the maximum practical life, their estimation is for about 50000 charging cycles. The cost of the electrodes is relatively low, and their manufacturing requires nothing novel or unconventional. That said, the system could theoretically be deployed widely and start capturing CO2 while spending little energy in the process (40-90 kJ per mole of captured CO2).
You can read the paper submitted by MIT to the Energy and Environmental Science Journal here.