A new technique to remove carbon dioxide from the air developed by researchers from the Massachusetts Institute of Technology can prove significant in combatting climate change.
The new system works on the gas at any concentration level, even down to the roughly 400 parts per million currently found in the atmosphere, claimed the research published in the journal Energy and Environmental Science.
According to researchers, most methods of removing carbon dioxide from a stream of gas require higher concentrations such as those found in the flue emissions from fossil fuel-based power plants. But the new less energy-intensive and inexpensive method can even work with low concentrations found in the air.
MIT postdoc Sahag Voskian, who developed the new technique during his PhD, and T Alan Hatton, the Ralph Landau Professor of Chemical Engineering, suggest the large and specialized battery technique was based on passing air through a stack of charged electrochemical plate that absorbs carbon dioxide from the air (or other gas streams) while charging, and releases the gas as it is being discharged.
The device during operation alternates between charging and discharging, with fresh air or feed gas blown through the system during the charging cycle, and the concentrated carbon dioxide is blown out during the discharging.
"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, and the new capture method is a clear demonstration of the power of electrochemical approaches that require only small swings in voltage to drive the separations," Voskian said.
He said the system in the lab withstood at least 7,000 charging-discharging cycles, with a 30 per cent loss in efficiency over that time, and could over the time be improved to 20,000 to 50,000 cycles.
"And the system is very easy to scale up. If you want more capacity, you just need to make more electrodes," he said.
The electrodes coated with a compound called polyanthraquinone, which is composited with carbon nanotubes, have a natural affinity for carbon dioxide and readily react with its molecules in the airstream or feed gas even when it is present at very low concentrations, said researchers, and reverses reaction takes place when the battery is discharged.
"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," Voskian explained.
He continued that fossil fuel is burned in some soft drinks plants to generate the carbon dioxide needed to give the drinks their fizz, and the new system can eliminate the need for fossil fuels. In the process, it actually takes the greenhouse gas right out of the air.
He added the pure carbon dioxide stream could be compressed and injected underground for long-term disposal or even make fuel through a series of chemical and electrochemical processes.
The researchers have even set up a company called Verdox to commercialize the process, and hope to develop a pilot-scale plant within the next few years.
