Removing carbon dioxide from the atmosphere to halt climate change

With ever-increasing emissions and climate change, removing greenhouse gases such as carbon dioxide from the atmosphere is of critical importance. Researchers at the Massachusetts Institute of Technology (MIT) have developed a means of removing carbon dioxide from a stream of air that functions at nearly any concentration level, making the technology far more versatile than others before.

MIT postdoctoral student Sahag Voskian, who worked under Chemical Engineering Professor Ralph Landau, published the findings in the journal Energy and Environmental Science. His technique involves forcing air through a stack of charged electrochemical plates, and releasing gas as the electrodes charge up. Previous attempts at carbon dioxide removal have required higher concentrations of the gas in the air, but Voskian’s device requires significantly less energy and works under more conditions.

“The greatest advantage of this technology over most other carbon capture or carbon-absorbing technologies is the binary nature of the adsorbent's affinity to carbon dioxide,” explained Voskian in an MIT press release. The electrodes are coated with a carbon nanotube-based compound called polyanthraquinone, so they have a natural affinity for carbon dioxide molecules and react with the gas even at low concentrations. The device can even supply some of the power required for the process of ejecting the carbon dioxide gas, unlike alternative methods that require substantial input energy, often in the form of heat.

Voskian continued, “This binary affinity allows capture of carbon dioxide from any concentration, including 400 parts per million, and allows its release into any carrier stream, including 100 percent CO2.” In other words, carbon dioxide will be emitted from the device regardless of the gas blown through its electrochemical plates. A common use case may be for the carbonation of bottled beverages, currently done by burning fossil fuels to generate the necessary carbon dioxide gas.

“In my laboratories, we have been striving to develop new technologies to tackle a range of environmental issues that avoid the need for thermal energy sources, changes in system pressure, or addition of chemicals to complete the separation and release cycles,” Hatton added. “This carbon dioxide capture technology is a clear demonstration of the power of electrochemical approaches that require only small swings in voltage to drive the separations.”

The electrodes can be manufactured using existing technologies, making the device relatively inexpensive to produce. On a larger scale, the cost can be reduced to around tens of dollars per square meter of the electrodes. More importantly, Voskian’s system consistently uses approximately one gigajoule of energy per ton of carbon dioxide captured. Other methods of carbon dioxide capture can use up to 10 gigajoules per ton and are composed of more expensive components

The researchers are commercializing the device through a new company called Verdox and hope to build a pilot plant within the coming years. Voskian believes it will be easy to scale up from there: “If you want more capacity, you just need to make more electrodes.”