Campus researchers help develop new technology to reduce carbon emissions

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A new technology developed in part by UC Berkeley researchers aims to increase the efficiency and effectiveness of carbon dioxide extraction, paving the way for new strategies to slow climate change.

Developed jointly with scientists in Switzerland and China, the new technology, called a carbon capture “slurry,” combines the two most popular methods of removing carbon dioxide from emissions released by factories and power plants.

There are currently two main processes for removing carbon dioxide from emissions: one that uses a solid powder and one that uses a liquid.

Powders remove carbon dioxide by sticking to the molecules in gaseous emissions and are comprised of metal-organic frameworks, or MOFs. MOFs are three-dimensional structures with surface pores to which carbon dioxide molecules stick. Liquids, on the other hand, absorb the carbon dioxide. Powders are more effective in capturing carbon dioxide and less expensive than liquids but are more difficult to transport and therefore harder to process.

While these are both effective technologies to remove carbon dioxide, neither are widely used due to high costs and energy inefficiency.

The slurry — the first of its kind — is a mixture of a solid powder and a liquid that “combines the better separation technology of a solid and the better heat integration and material transport properties that a liquid solvent offers,” said Marjorie Went, a campus chemical and biomolecular engineering lecturer who was not involved in the research.

In creating the slurry, researchers had to ensure that the pores on the MOF they used, ZIF-8, were large enough to collect the carbon dioxide molecules but not large enough that the liquid molecules would fill them. They tested a variety of liquids, including ethanol, hexane and methylbenzene, but the molecules of these liquids were smaller than ZIF-8’s pores. The researchers found glycerol to be the most effective, as its molecules were larger than the pores.

The slurry uses the same energy-efficient regeneration process as liquids. This process occurs in two large columns: one that captures the carbon dioxide and one that separates the molecules from the solution. After they’re separated, the slurry or liquid can be used again.

Because this technology removes carbon dioxide from emissions, experts say it presents a huge potential for slowing global warming.

“Anything that can reduce the amount of energy required to separate carbon dioxide will bring us one step closer to mitigating the effects of climate change,” Went said.

Li-Chiang Lin, who worked on this study while pursuing his doctorate at UC Berkeley, said this new technology opens the door for more efficient carbon capture technology.

“Before, we only had the parameters of liquid and solid,” he said. “(With the slurry) we opened up so many possibilities.”

Contact Sonja Hutson at [email protected] and follow her on Twitter @SonjaHutson.