Scientists use liquid metals to turn carbon dioxide gas back into coal

Researchers have developed a new way to turn captured carbon dioxide gas into solid "coal"
Researchers have developed a new way to turn captured carbon dioxide gas into solid "coal"
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An illustration depicting how the new process works
An illustration depicting how the new process works
RMIT researchers Torben Daeneke (left) and Dorna Esrafilzadeh (right) with a sample of the liquid metal catalyst
RMIT researchers Torben Daeneke (left) and Dorna Esrafilzadeh (right) with a sample of the liquid metal catalyst
Researchers have developed a new way to turn captured carbon dioxide gas into solid "coal"
Researchers have developed a new way to turn captured carbon dioxide gas into solid "coal"

If we're going to curb the worst case scenario of climate change, it's not enough to just cut back on future carbon dioxide emissions – we need to remove some of what's already in the air. Capturing carbon from the air and sequestering it is emerging as a viable strategy, and now scientists have developed a new method to turn CO2 gas back into solid coal, that can then be buried, or even used for electronic components.

Many projects are currently experimenting with new ways to capture carbon from the point of emission. The gas is run through and absorbed by metal-organic frameworks, porous powders, bubble-like membranes, or materials made of clay or coffee grounds.

But that's only half the story – what do you do with that captured carbon? After it's extracted from those capture materials, the gas can then be reused to make concrete, fizzy drinks or fuels, or in larger amounts it can be stashed away underground. To store CO2, it's usually compressed into a liquid form or bonded with water, and then injected deep underground. There, it interacts with basalt rock and solidifies into a carbonate mineral, reportedly in as little as two years.

But other studies have found that this process may not be as effective as it seems. An MIT investigation found that only a thin top layer was turning solid – underneath was still a large pocket of gas. That keeps it out of the atmosphere for now, but has the potential to leak in the future and release it all back into the air, undoing all our hard work.

So the new study set out to develop a way to solidify carbon before it's stashed underground, so there's no chance of escape. The team was made up of researchers from Australia, Germany, China and the US.

An illustration depicting how the new process works
An illustration depicting how the new process works

Solidifying carbon at room temperature

Key to the new method is a liquid metal catalyst, made up of a gallium alloy and cerium, which was developed by the team. Carbon dioxide is first dissolved into a beaker containing an electrolyte liquid, then a small amount of the liquid metal catalyst is added. When an electrical current is applied, the catalyst chemically activates the surface of the mixture, which slowly converts the CO2 into solid flakes of carbon.

The catalyst was designed to be an excellent conductor of electricity, and efficient at performing the reaction. And because it's a liquid the carbon flakes don't stick to it, which they tend to do if it's a solid catalyst. That keeps it running for longer without fouling up.

The researchers say this process can be done at room temperature, unlike other carbon conversion processes that require high temperatures and, as a result, consume a lot of energy. This method meanwhile can be done in a lab with relatively inexpensive and commonplace equipment, and a small source of electricity.

"To date, CO2 has only been converted into a solid at extremely high temperatures, making it industrially unviable," says Torben Daeneke, an author of the study. "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. While more research needs to be done, it's a crucial first step to delivering solid storage of carbon."

RMIT researchers Torben Daeneke (left) and Dorna Esrafilzadeh (right) with a sample of the liquid metal catalyst
RMIT researchers Torben Daeneke (left) and Dorna Esrafilzadeh (right) with a sample of the liquid metal catalyst

Solid carbon

Once that carbon has been solidified, it can then be safely stored underground indefinitely, without fear of it leaking back into the atmosphere. But interestingly, that isn't the only potential outcome.

"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," says Dorna Esrafilzadeh, lead author of the study. "The process also produces synthetic fuel as a by-product, which could also have industrial applications."

The technique has plenty of potential for helping to remove greenhouse gases from the atmosphere, but as with any of these kinds of studies, more research will need to be done to see how effective it could be at an industrial scale, both logistically and economically.

The research was published in the journal Nature Communications. The team describes the work in the video below.

Source: RMIT

Turning carbon dioxide back into coal | RMIT University

IMHO, real big use of this tech maybe space/moon/mars-stations! I think, currently, oxygen for astronauts, is either produced from (one-time-use) chemicals, or, by splitting water (again, one-time-use)! IMHO, a tech that, efficiently, takes CO2 from air & converts to oxygen (to release back to air) & carbon (powder to dump away), using only electricity, in room temp, should be invaluable for astronauts in space! (Because, it would mean a huge drop/savings in amount of cargo, which needs to be carried into space, for astronaut life support!!!)
So many scientists pushing this hard in the age of computer learning will find a solution very soon, and become billionaires doing so.
The final link in the article allows you to read the full paper for more details. The YouTube video is a puff piece and not worth viewing IMHO.
The planet's climate has been changing for the past 4.5 billion years. The climate swings dramatically from glacial to interglacial largely due to our planet's orbit being affected by Venus and Jupiter every 405,000 years or so. And contrary to what many anthropological climate scaremongers say, the climate has actually changed much more rapidly on many occasions in the last few hundred million years. The Antarctic used to be a tropical paradise. Today's tropics used to be covered in snow. Land bridges used to link Pacific islands with the Asian mainland. Instead of spending hundreds of billions, if not trillions, of dollars fighting nature, shouldn't mankind be using our resources in order to better adapt to the changes that naturally occur over time?
So how many tons of gallium would be needed for the emissions from one power plant?
Bob Stuart
More research is not needed to know that this requires more renewable energy input than just not burning the coal. It can't overcome the initial inefficiency, however efficient the catalyst makes it at using the electricity.
Unless there is surplus renewable energy this is a waste of time as more CO2 would be produced creating the energy required than it captures.
Simon Redford
Carbon Capture is a wasteful con - don't use renewables to capture CO2 - what a waste of a resource. Put more money into the less exciting ways to avoid using as much energy in the first place (insulation) and into having cost effective renewables and storage options. Best 'capture' technology is planting more trees, managing forests effectively and not de-foresting for agriculture. Whenever I hear about carbon capture and carbon harvesting from the atmosphere I think (expensive) snake oil. The headline "..back into coal" had me immediately thinking of a perpetual motion machine!
Mother Nature figured this out eons ago. Trees.
Expanded Viewpoint
Waaaay back in about 1969 or so, I was taught that about 70% of Earth's Oxygen comes from the plants in the ocean. These green organisms (algae) living there take in Carbon Dioxide, use some sun light and Hydrogen to create sugars and give off Oxygen as a waste product. The Carbon is recycled like water, by Nature. Let Nature do its thing. Randy