A team of engineers from MIT have developed a new way to remove carbon dioxide from the air.
The new tech could work on the green-gas at any concentration which means it could be used to capture not just CO2 from power plant emissions but from the open air.
The new method works by removing carbon dioxide from a stream of air. However, it is a potential game-changer as up to now, the struggle has been to pull CO2 from the atmosphere due to the relatively low (around 400 parts per million) concentration.
It is hoped that the tech will provide a significant tool in the battle against climate change.
Existing methods of removing CO2
Currently, our best methods of removing carbon dioxide from a stream of gas require high concentrations of the gas.
For example, carbon capture techniques currently found in the flue emissions from fossil fuel-based power plants are dealing with much high concentration than in the earth’s atmosphere. Coal with a carbon content of 78% typically emit about 204.3 pounds of carbon dioxide per million.
While a few variations in existing tech exist that can work with the low concentrations found in air the new method is significantly less energy-intensive and expensive.
How does the MIT Carbon Capture Technique Work?
The system works with air entering from top right and passing to one of two chambers (the grey rectangles) which contain 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.
The new technique is based on passing air through a stack of charged electrochemical plates.
The simple way to think of the device is as a large specialized battery that can absorb carbon dioxide from the air (or any gas stream).
It works by passing air over its electrodes as it is being charged up, and can then releases the gas as it is being discharged.
The process relies on an electrochemical reaction which takes place at the surface of each of a stack of electrodes. Each of these is coated with a compound called polyanthraquinone (a composited of carbon nanotubes).
Each of these electrodes has a natural affinity for carbon dioxide and reacts with the CO2 molecules even when it is present at very low concentrations. Then the reverse reaction takes place when the battery is discharged and the system then ‘ejects’ a stream of pure carbon dioxide.
Unlike other similar systems, the whole process is able to operate at room temperature, normal air pressure and the electrodes themselves can be manufactured by standard chemical processing methods.
In the real world, the device can be used by simply alternating between charging and discharging. Pulling in fresh air during the charging cycle, and then allowing engineers to store the pure, concentrated carbon dioxide blown out during the discharging however they choose.
The system is relatively energy-efficient and uses one gigajoule of energy per ton of carbon dioxide captured. While existing methods of energy consumption vary between 1 to 10 gigajoules per ton.
The team now want to look at how the electrodes could be adapted so that the system can be manufactured at large scales. They believe that if they could use a roll-to-roll manufacturing process (similar to a newspaper printing press) that each electrode could be produced at a cost of tens of dollars per square meter making it widely affordable.
The researchers have set up a company called Verdox which will now look at how to commercialize the process, and want to develop a pilot-scale plant within the next few years.
