Researchers have developed a new technology for capturing carbon dioxide from an air stream virtually at any level of concentration. It is a breakthrough that could open the way for new strategies to reduce greenhouse gas levels in the atmosphere.
US researchers at the Massachusetts Institute of Technology (MIT) said that although most of the methods used to extract carbon dioxide from a gas stream needed higher concentrations such as those contained in flue emissions from fossil-fuel power plants.
We added that the system required significant energy and even suck out the greenhouse gas at the current atmosphere of about 400 parts per million.
In a study published in the journal Energy and Environmental Science, the researchers identified the device as a large, specialized battery with an electrode stack which absorbs carbon dioxide from the air that passes through its charged surface and then releases the gas as it discharges.
The researchers said the system was alternating between cycles of charging and discharging.
They said fresh air was fed into the system during the charging cycle, and concentrated carbon dioxide was blown out during the discharge.
The study noted that as the battery charges, a chemical reaction occurs on the surface of each stack of electrodes. The researchers said that a compound called polyanthraquinone combined with carbon nanotubes coats the electrodes. The study noted that the electrodes have a natural carbon dioxide affinity and were ready to react in the airstream or feed gas with their molecules.
The researchers said the process ejects a stream of pure carbon dioxide when the battery is discharged and also provides part of the power required for the entire system.
“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,” said Sahag Voskiano, study co-author of MIT.
He said that by its definition, the electrode material “has either a high affinity or no affinity at all,” depending on the charging or discharge condition of the battery. And this device operates at room temperature and normal air pressure.
“This binary affinity allows capture of CO2 from any concentration, including 400 parts per million and allows its release into any carrier stream including 100% CO2,” Voskian said.
According to researchers, through a series of chemical and electrochemical processes, the pure carbon dioxide stream could be compressed and injected underground for long-term disposal or even made into fuel.
Voskian said the new system is energy-efficient compared to existing methods, it consistently using approximately one gigajoule of energy per ton of captured carbon dioxide. He said that the energy consumption of other existing methods ranges between 1 and 10 gigajoules per ton depending on the concentration of carbon dioxide inlet. And the energy consumption of other existing methods ranges from 1 to 10 gigajoules per ton depending on the concentration of carbon dioxide inlet.