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Cleaning the Air: Researchers Turn CO2 Back Into Coal

Researchers at the RMIT University in Melbourne, Australia have developed a breakthrough carbon capture technology to turn carbon dioxide back into solid carbon using liquid metals. This new technology offers a safe and fairly inexpensive way to remove harmful CO₂ emissions from the atmosphere. While the research isn’t complete just yet, it’s a major step in safely delivering carbon dioxide back into the ground.

There are other ways in existence to capture and store carbon dioxide, but most involve compressing the gas into a liquid form and injecting it into the ground. Although it is a good method, there are concerns about it being economically practical and environmentally safe, as leaks from the storage sites can potentially do more harm than good. Being able to directly convert CO₂ into a solid is a much more sustainable approach.

“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,” says Dr. Torben Daeneke, an Australian Research Council DECRA Fellow. “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.”

How Carbon Conversion Works

The technology to turn carbon dioxide into solid carbon was developed by Dr. Dorna Esrafilzadeh, a Vice-Chancellor’s Research Fellow in RMIT’s School of Engineering.

The design uses a liquid metal catalyst with surface properties that conduct electricity extremely well while chemically activating it. The carbon dioxide is dissolved in a liquid electrolyte solution mixed with a small amount of the liquid metal, which is then charged under an electrical current. This allows the CO₂ to slowly combine into small, solid flakes of carbon on the liquid metal surface which are removed as the process continues.

This process of converting carbon dioxide into solid carbon comes with two beneficial side effects. First, the carbon created in the process can hold an electrical charge and becomes a supercapacitor which could be used in machinery such as vehicles. The second side benefit is that a synthetic fuel is created as a by-product from the carbon conversion process, which could have many industrial purposes.

The paper on RMIT’s research was published in Nature Communications.

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