A harmless yellow powder, created in a laboratory, could be a new way to combat the climate crisis by absorbing carbon from the air.
Just half a pound of the stuff can remove as much carbon dioxide as a tree, according to early tests. Once the carbon is absorbed by the powder, it can be released into safe storage or used in industrial processes, such as cooling beverages.
“This really addresses a big problem in the technology field, and it now presents an opportunity for us to scale it up and start using it,” said Omar Yaghi, a chemist at the University of CaliforniaBerkeley. It is not the first material to absorb carbon, but “it is a quantum leap forward [of other compounds] in terms of the durability of the material”.
The powder is known as a covalent organic framework, with strong chemical bonds that pull gases from the air. The material is both durable and porous, and can be used hundreds of times, making it better than other materials used for carbon capture.
Yaghi has been working on similar materials for decades. It is part of a wider effort to collect small amounts of carbon from the air – either from power plants or from air around cities. Yaghi’s research with Zihui Zhou, a graduate student in his lab, and others was published in the journal Nature last month.
In the lab, Yaghi’s team tested the new powder and found that it could successfully absorb and release carbon more than 100 times. It becomes full of carbon in about two hours and then needs to be heated to release the gas before starting the process again. It only requires a temperature of about 120F to release the carbon; this makes it an improvement over other methods, which require a much higher temperature.
This feature means places that already produce extra heat – such as factories or power plants – can use it to release the gas and start the cycle again. The material can be incorporated into existing carbon capture systems or future technology.
Yaghi says he can imagine a future in which people build huge plants with the material in every city of 1 million people or more around the world. He has plans to scale the use of this type of carbon capture with his Irvine, California-based company, Atoco, and believes the powder can be produced in multiton quantities in less than a year.
Shengqian Ma, a chemist at the University of North Texas who was not involved in the new work, says this technology could be game-changing. “One long-standing challenge for direct air capture lies in the high regeneration temperatures,” he says, adding that the new material can significantly reduce the energy needed to use direct air capture, making it “very new” and “very promising.” .
“We need to reduce our greenhouse emissions, and we need to do it quickly,” said Farzan Kazemifar, a mechanical engineer at San Jose State University who was not involved in the new study. “In the short term, replacing large emitters of carbon dioxide – such as coal-fired power plants – with renewable electricity offers the fastest reduction in emissions. But in the long term, in case emissions do not fall at the desired rate, or if global warming effects intensify, we may have to rely on technologies that can remove carbon dioxide from the atmosphere, and direct air capture is one of those technologies.”
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Still, removing carbon from the air remains difficult, and as with all early-stage lab-scale studies, the challenge is scaling up the system for pilot studies. The concentration of carbon dioxide, although increasing, now stands at about 400 parts per million, or 0.04%. This means that any technology to capture the gas from the air requires large volumes of air, and this requires large electricity consumption for running fans, says Kazemifar. “I believe the high energy intensity of the process is the biggest challenge of all [direct air capture] technologies.”
Some scientists worry that the expectations of direct air capture systems have been too rosy. A group of scientists from MIT recently wrote a paper analyzing the assumptions of many climate stabilization plans, and pointing to ways in which direct air sampling may be overly optimistic.
Ma also points out that a major challenge in using this approach to combat climate change lies in the high cost of materials for creating substances that capture carbon.
Still, Yaghi says this material could change the way we address carbon removal. “It’s something we’ve been working on for 15 years, which basically addresses some of the ongoing problems,” he says. “That gives us no excuse now [not] to start thinking more seriously about taking carbon dioxide out of the air.”
