- A new way of removing CO2 from a stream of air using electrodialysis could be a significant tool in the battle against climate change.
- This new carbon reduction technology of electrolysis, developed by Meenesh R. Singh, can work on the gas even on a small scale, not necessarily only by industrial companies.
- Singh’s electrodialysis device can continuously remove CO2 at high rates from the air; a scaled-up version should be able to trap CO2 for $145 per metric ton.
- The electrochemical device uses simple chemicals to soak up CO₂ 100 times faster than current methods.
Scientists have developed a carbon capture device that traps CO2 almost 100 times faster than most current systems with electrodialysis.
They can make this system trap CO2 directly from the air or even from a smokestack exhaust.
But considering how affordable and efficient the technology is, the carbon can be captured at a small scale as well. Chemical engineer from the University of Illinois Chicago Meenesh R. Singh is confident in this.
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According to him, even a tiny humidifier can trap one kilogram (~2.2 lbs) of carbon each day.
Most carbon capture systems use solid sorbents or amine-based solutions, which allows for the separation of CO2 from a mixture of gasses.
These technologies are expensive and intensive because of the huge amount of heat required to release the gas from saturated material.
A new approach – Electrodialysis
Electrodialysis is another technique that effectively moves ions across a charged membrane. It is commonly used for desalination, but now it has been used to trap CO2 as well.
This is how it works:
- A solution of KOH in ethylene glycol stays on one side of the positively charged membrane, while the water stays on the other. This is congested by the electrodes.
- As soon as the flue gas is put on the KOH side, the hydroxide ions combine and react with CO2 to produce negatively charged bicarbonate ions.
- The water is passed outside the porous cathode creating hydroxide ions which will later replenish the KOH.
- Simultaneously, bicarbonate ions move towards the anode to the more aqueous side of the cell.
- At this moment, water stimulates their conversion into CO2 for utilization or storage without the need for excess heat.
This fizz created in this reaction is similar to what we observe when mixing baking soda in water.
How much can it trap?
- A 4 cm² (~0.6 sq in) device can efficiently capture 3.3 mmol of CO2/h.
- A large-scale system with a capturing capacity of 1000 metric tons of CO2 per hour will cost $145 per ton.
- The target cost for carbon removal technologies, according to DOE, is $200/ton.
- In Iceland, a direct air capture (DAC) plant removed CO2 using solid sorbents at $600/ton.
The flue gas has moisture, affecting the carbon capture efficiency of any new device, says Tao Wang of Zhejiang University.
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This technical difficulty needs to be solved at a large scale to make this technology efficient.
However, in the end, this innovative approach to capture CO2 via electrodialysis which is easily modularized and powered using renewable energy, is a promising alternative.
It can replace carbon capture systems run by thermal energy and could make the world a better place.
