Invented powder that can absorb CO2 more effectively than trees

According to a study published in the journal Nature on October 23, there is a powder that can help absorb carbon dioxide more effectively than planting trees.

A typical tree, as it grows, can suck up to 40kg of carbon dioxide out of the air over the course of a year. Now scientists at the University of Berkeley say they can do the same with about 200 grams of a fine yellow powder.

The tiny holes in the powder can trap greenhouse gases, according to a study published in the journal Nature on Oct. 23. The greenhouse gases could then be captured from the powder and stored somewhere where they could not contribute to global warming. In tests, the material remained in good condition after 100 such cycles.

It works very well: 'Based on the stability and activity of the current material, we think it will work for thousands of cycles,' says Omar Yaghi, a lattice chemist at UC Berkeley and lead author of the study.

Molecular structure of COF-999.

Called COF-999 , the powder could be deployed in the types of large-scale direct air capture plants that are starting to come online to reduce the amount of carbon in the atmosphere.

Scientists say keeping atmospheric carbon dioxide levels below 450 parts per million (ppm) is needed to limit global warming to 2 degrees Celsius above pre-industrial levels and prevent some of the most catastrophic consequences of climate change. Measurements taken at the Mauna Loa Observatory in Hawaii show CO2 levels _currently stand at around 423 ppm.

'You have to take CO2 _out of the air — there's no better way, ' said Yaghi, who is also chief scientist at the University of California, Berkeley's Institute for Digital Materials. 'Even if we stopped emitting _CO2 , we still need to take it out of the air. We have no choice.'

Klaus Lackner, founding director of the Center for Carbon Emissions Reduction at Arizona State University, agrees that direct air capture will become an important tool for sequestering carbon and cooling the planet once it overcomes significant hurdles. He says new research advances could help.

'We're opening the door to a whole range of new approaches,' said Lackner, who was not involved in the study.

When viewed under a scanning electron microscope, the powder particles look like tiny basketballs with billions of holes, according to team leader Zihui Zhou, a materials chemist and doctoral student at the University of California, Berkeley.

The structures are held together by some of the strongest chemical bonds in nature, including those that turn carbon atoms into diamonds. Compounds called amines are inserted between the bonds.

As air flows through the structures, most of its components pass through undisturbed. But the amines, which are basic, attract the carbon dioxide molecules, which are acidic.

_{Those CO2} molecules will stay there until scientists break them up using heat. They can then suck them up and pump them deep underground to keep them from escaping into the atmosphere.

Once the carbon dioxide is removed from the powder, the whole process can begin again. To test COF-999's carbon-cleaning abilities, the researchers packed the powder into a stainless steel tube the size of a straw and exposed it to outdoor air for 20 consecutive days.

When it entered the tube, Berkeley air contained CO2 _at concentrations ranging from 410 ppm to 517 ppm, Zhou said. When it exited on the other side, scientists could not detect any carbon dioxide.

According to the creators of COF-999, the powder has several advantages over other materials. Its porous structure increases the surface area, meaning there are more places to hold _CO2 molecules . As a result, COF-999 captures carbon dioxide at a rate 'at least 10 times faster' than other materials used to capture air directly.

Another plus is that COF-999 loosens its grip on CO2 _when it is heated to about 60 degrees Celsius . Zhou said that comparable materials must be heated to 120 degrees Celsius to extract the carbon, which is very energy-intensive, and energy-intensive processes are more likely to emit greenhouse gases than energy.

The powder is also more durable. Zhou said the team tested a newer version that could last 300 cycles before the experiment was terminated.

That's a good sign, Lackner said. "Doing 100 cycles and not seeing any degradation suggests we can do thousands of cycles. We don't even know if we can do hundreds of thousands of cycles," he said.

The team has continued to improve it, and they are on track to double its capacity next year. To deploy it on an industrial scale, Zhou said, it would require designing large metal boxes that can let air pass through but not blow away the powder. Those boxes would need to be grouped together in numbers, like a modern chemical or oil plant.

Yaghi said a version of COF-999 could be ready for direct air capture plants within two years. He could not estimate the cost of mass production, but he said it would not require any expensive or exotic materials.

Yaghi has formed a company, Atoco, based in Irvine, to commercialize his research into carbon capture and other technologies. Atoco helped fund the new research. In addition, the University of California, Berkeley, has filed a patent application for COF-999, naming Yaghi and Zhou as inventors.

Lackner said the entire direct air capture process would have to become '10 times cheaper than it is today.' Only then could the technology have a real impact on the hundreds of billions of tons of carbon dioxide that scientists want to remove from the atmosphere.

A material that is more efficient at capturing CO2 _would help, but Lackner said he spends more time worrying about issues like how much energy it takes to put carbon into the ground, since that energy consumption itself warms the Earth. 'There are a thousand things that go into that,' he said .