Carbon capture material “cleans air entirely of carbon” say excited scientists

Researchers in Berkeley, California have created a new material they believe might hold the key to capturing carbon from the atmosphere more cheaply and efficiently.  

Carbon capture technologies exist but mostly only work well for concentrated sources of carbon like emissions from power plant exhausts and flues. These methods don’t translate efficiently or cheaply to capture carbon dioxide from ambient air where concentrations are hundreds of times lower.

The Intergovernmental Panel on Climate Change (IPCC) has stressed that the removal of greenhouse gases from the atmosphere is critical to reverse the rise of CO₂ levels. Currently, CO₂ levels in the atmosphere are 50% higher than before the industrial revolution.

IPCC reports say that carbon capture is necessary if we are to limit global warming.

The research, published in Nature, describes a new absorbing material which could do the job cheaply and efficiently.

The porous material is a covalent organic framework (COF). The rigid molecular structure has regularly spaced internal pores to which gas molecules stick or absorb.

“We took a powder of this material, put it in a tube, and we passed Berkeley air – just outdoor air – into the material to see how it would perform, and it was beautiful,” says senior author Omar Yaghi, a professor at the University of California (UC), Berkeley. “It cleaned the air entirely of CO₂.”

“I am excited about it because there’s nothing like it out there in terms of performance. It breaks new ground in our efforts to address the climate problem,” he adds.

Just 200g of the material can take up about 20kg CO₂ in a year – about the same as a tree.

“Flue gas capture is a way to slow down climate change because you are trying not to release CO₂ to the air,” says first author Zihui Zhou, a UC Berkely graduate student. “Direct air capture is a method to take us back to like it was 100 or more years ago.”

“Currently, the CO₂ concentration in the atmosphere is more than 420 ppm (parts per million), but that will increase to maybe 500 or 550 before we fully develop and employ flue gas capture. So if we want to decrease the concentration and go back to maybe 400 or 300 ppm, we have to use direct air capture.”

“Trapping CO₂ from air is a very challenging problem,” Yaghi says. “It’s [energy] demanding, you need a material that has high carbon dioxide capacity, that’s highly selective, that’s water stable, oxidatively stable, recyclable. It needs to have a low regeneration temperature and needs to be scalable. It’s a tall order for a material.”

Yaghi’s team has spent 20 years developing the material that has a strong enough backbone to withstand contaminants, ranging from acids and bases to water, sulphur and nitrogen, that degrade other porous solid materials.

“This COF has a strong chemically and thermally stable backbone, it requires less energy, and we have shown it can withstand 100 cycles with no loss of capacity. No other material has been shown to perform like that,” Yaghi says. “It’s basically the best material out there for direct air capture.”