Too much carbon in the air? Take it out, say scientists

Is carbon capture and sequestration the answer to our climate woes or merely a way to preserve the fossil fuel industry? John Dyer reports. 

Image credit: Rich via Flickr

Politicians, corporate leaders and others have been calling for more research on carbon sequestration.

British academics have posited that carbon storage in the UK’s now-shuttered North Sea oilfields could become big business. Norway supports the CLIMIT institute to study carbon capture and storage. The United States recently enacted tax credits for sequestration or use of stored carbon, reported Axios.

Critics have said carbon capture is simply a way to preserve the fossil fuel industry, however. In the US, for example, the fracking industry uses captured carbon for so-called “enhanced oil recovery”. Others have said it is too costly.

But scientists and entrepreneurs have nonetheless pursued visions to remove carbon from the atmosphere.

The NRG COSIA Carbon XPRIZE offers international teams $20 million to develop technologists that capture emissions from power plant and factories and turn them into valuable products.

“Solutions are already exciting, especially the unexpected range and diversity of technologies and products under development,” said Marcius Extavour, the prize’s executive director, on the organization’s website. “Teams are trying to make everything from carbon fiber, to fish food, to toothpaste, to building blocks.”

Turning carbon into coal

Scientists in Australia have developed a process that converts carbon dioxide into coal.

“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,” said RMIT University researcher Torben Daeneke in a press release.

Researchers have been able to turn carbon dioxide into a solid under extremely high temperatures, but that process is too expensive.

Publishing their work in the journal Nature Communications, Daeneke and his colleagues used liquid metals as catalysts to trigger the greenhouse gas’s transformation into a solid at room temperature.

The liquid metals conduct electricity, activating chemical processes around them. When carbon dioxide is dissolved into a beaker with an electrolyte liquid and the metals and combined with an electric charge, the carbon dioxide turns into chunks of carbon that fall from the liquid metal, allowing more to form from the gas in the beaker.

“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,” said Daeneke.

The coal that forms could be used for other processes, too.

“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,” said Dorna Esrafilzadeh, another RMIT University researcher. “The process also produces synthetic fuel as a by-product, which could also have industrial applications.”

Artificial leaf extracts CO2 from the air

At the University of Illinois Chicago, researchers have produced artificial leaves that mimic photosynthesis, using sunlight to produce carbohydrates from water and carbon dioxide they extract from the air.

Around 1.7 metres long and 0.2 metres wide, the leaf pulls carbon dioxide from the air as water evaporates off its surface. A device within the leaf then convert the carbon dioxide to carbon monoxide. Oxygen is released in the chemical process. Carbon monoxide is commonly used in synthetic fuels.

“The whole unit is able to function outside, like a natural leaf,” said Meenesh Singh, a chemical engineer at the university, in a statement.

Publishing their findings in the journal ACS Sustainable Chemistry & Engineering, the researchers claimed their leaf was at least 10 times more efficient than natural leaves at removing carbon from the atmosphere.

Around 360 of the leaves covering a 500-metre-square area would produce around half of tonne of carbon monoxide for synthetic fuels every day, they said. In the same period, carbon dioxide levels within 100 metres of the array would fall 10 per cent.

The technology paves the way for more effective leaves in the future, said Singh.

“In order to implement successfully in the real world, these devices need to be able to draw carbon dioxide from much more dilute sources, such as air and flue gas, which is the gas given off by coal-burning power plants,” he said.

You may also like...

Leave a Reply