Capturing and storing the carbon dioxide humans produce is key to lowering atmospheric greenhouse gases and slowing global warming, but today’s carbon capture technologies work well only for concentrated sources of carbon, such as power plant exhaust. The same methods cannot efficiently capture carbon dioxide from ambient air, where concentrations are hundreds of times lower than in flue gases.
Yet, direct air capture, or DAC, is being counted on to reverse the rise of CO2 levels, which have reached 426 ppm, 50% higher than levels before the Industrial Revolution. Without it, according to the Intergovernmental Panel on Climate Change, we won’t reach humanity’s goal of limiting warming to 1.5°C above preexisting global averages.
A new type of absorbing material developed by chemists at the University of California, Berkeley, could help get the world to negative emissions. The porous material—a covalent organic framework (COF)—captures CO2 from ambient air without degradation by water or other contaminants, one of the limitations of existing DAC technologies.
“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. It cleaned the air entirely of CO2. Everything,” said Omar Yaghi, the James and Neeltje Tretter Professor of Chemistry at UC Berkeley and senior author of a paper in the journal Nature.
“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 added.
According to Yaghi, the new material could be substituted easily into carbon capture systems already deployed or being piloted to remove CO2 from refinery emissions and capture atmospheric CO2 for storage underground.
UC Berkeley graduate student Zihui Zhou, the paper’s first author, said that a mere 200 g of the material, a bit less than half a pound, can take up as much CO2 in a year—20 kg—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. Direct air capture is a method to take us back to like it was 100 or more years ago,” Zhou said. “Currently, the CO2 concentration in the atmosphere is more than 420 ppm, 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.”