Scientists discover way to convert CO2 back into coal in “world first”

By Ellen Daniel

Researchers have come up with a method of turning CO2 back into coal, which could transform carbon capture and storage.

In what has been described as a “world-first breakthrough”, researchers from RMIT University in Melbourne have used liquid metals to convert CO2 found in the atmosphere to a substance that can be stored, offering an alternative way to deal with greenhouse gases.

Current technologies for carbon capture work by compressing CO2 into a liquid form and then storing it underground. However, this is an expensive process, and also raises environmental concerns over possible leaks of liquid CO2. Therefore, turning CO2 into a solid substance could be a solution.

To convert CO2, the researchers designed a liquid metal catalyst with properties that made it efficient at conducting electricity while chemically activating the surface.

The carbon dioxide is dissolved in a beaker filled with an electrolyte liquid and a small amount of the liquid metal, which is then charged with an electrical current. The CO2 then converts into solid flakes of carbon.

Turning CO2 into coal

Torben Daeneke, an Australian Research Council DECRA Fellow said that this could be a viable way of  reducing the CO2 in the atmosphere:

“While we can’t literally turn back time, turning carbon dioxide back into coal and burying it back in the ground is a bit like rewinding the emissions clock. To date, CO2 has only been converted into a solid at extremely high temperatures, making it industrially unviable. By using liquid metals as a catalyst, we’ve shown it’s possible to turn the gas back into carbon at room temperature, in a process that’s efficient and scalable.”

Lead author, Dr Dorna Esrafilzadeh, a Vice-Chancellor’s Research Fellow in RMIT’s School of Engineering said that turning CO2 into coal could also be used to produce an electrode, meaning it could have industrial uses:

“A side benefit of the process is that the carbon can hold electrical charge, becoming a supercapacitor, so it could potentially be used as a component in future vehicles.

“The process also produces synthetic fuel as a by-product, which could also have industrial applications.”