Capturing carbon dioxide from air or emissions and locking it in solid form could mitigate climate change and help industries such as steelmaking become carbon neutral in the future, says Greeshma Gadikota.

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Research in Focus: Greeshma Gadikota invents technologies to capture and upcycle carbon dioxide

Greeshma Gadikota, assistant professor of civil and environmental engineering in the College of Engineering, likes to take risks that other researchers wouldn’t contemplate. She wants her projects to push the boundaries so far beyond the parameters of current research that it creates a space most scientists don’t realize is there.

“This is a space where we don’t really know anything about problems that actually matter a lot to us,” she explains. “You become the first person to tread into that space. You don’t know if you’re going to fail. You don’t know if it’s worth it. All you know is that if life on this planet is going to live and thrive over the next hundreds of years, those questions are critical and need to be answered.”

For Gadikota, the critical questions are tied to global warming and the consequences of how we use our energy and resources. “For the longest time, people thought of energy and resource use as having their cake and eating it too,” she says. “But it’s not like that. There are impacts that need to be managed. There are planetary consequences to the problem of energy and resource recovery and conversion. And it’s a problem not only for humans but for all life forms on the planet. It impacts our ecological balance, if you will.”

Capturing Carbon, Making Chalk

One promising strategy for mitigating climate change is to capture carbon dioxide and hold it in a solid state that will not contribute to global warming. A large part of Gadikota’s research focuses on developing a portfolio of technologies for carbon capture, conversion, storage and removal – an approach that is gaining global attention.

Gadikota and members of her research group invented a process that can pull carbon dioxide directly from regular air or from flue-gas conditions, like those found in a smokestack at a steel mill. Through a process called reactive crystallization, the captured carbon dioxide is transformed into calcium carbonate, or chalk. “The technologies we’ve developed are relatively simple to look at, but the chemistry is quite complex,” she says.

Gadikota points out that similar reactive crystallization processes could be adapted to mining, cement making and iron and steel production. The technology could enable these industries to offset carbon emissions and work toward becoming carbon neutral or even carbon negative, meaning that they sequester more carbon than they emit.

The calcium carbonate produced by the process could be a valuable material, since many industries use it either in their products or in their manufacturing processes. In fact, Gadikota would like to see the mining of solid carbonates curtailed completely in favor of the reclaimed version.

“We should use solid carbonates that are made from anthropogenic CO2,” she says, referring to carbon dioxide that has been released into the atmosphere by human activity. “It should permeate all our day-to-day products, all our industrial and manufacturing processes.”

The innovations coming out of the Gadikota lab are of interest to a range of industries, including cement and steel making – both of which use calcium carbonate in their processes while at the same time emitting large amounts of carbon dioxide. “A lot of these companies have reached out to us,” she says. “They’ve asked us to figure out how they can make calcium carbonate from their CO2 emissions and then recycle it during the manufacturing process.”

In February 2022, the United States Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) awarded Gadikota a $2.5 million grant to find ways to take construction and demolition waste and convert it – using electricity generated from renewable energy resources – into a form that can be used in cement production. The ultimate goal is to make cement almost entirely from recycled carbon and other waste materials, essentially “closing the carbon and material cycles in cement making with the inherent reuse of construction and demolition wastes,” Gadikota says.

Carbonate Particles with Tunable Shapes and Sizes

Gadikota’s work on carbon recapture led to a $1.5 million grant from the Department of Energy Advanced Manufacturing Office in 2021 to investigate the possibility of producing nanoscale calcium carbonate for use in iron and steelmaking. “Our goal is to make particles with finely tuned shapes and sizes. So far, the results look very promising,” Gadikota says.

Gadikota and Yong L. Joo, the BP Amoco/H. Laurance Fuller Professor in the College of Engineering, are collaborating on a related project exploring the production of precisely sized carbonate particles for use in a wide range of industries. “We’re trying to come up with a reactor system where we can use the way fluids flow to tune the particle sizes of the carbonates we’re making,” Gadikota says of the project, which is supported by a Partnership for Innovation grant from the National Science Foundation (NSF). “This approach will enable us to meet the particle size needs for various applications, including paper manufacturing.

“If we can gain a lot of tunable controls over these processes, we can start meeting industry needs,” she continues. “That’s important. We want solutions that businesses can use, that people can wrap their heads around, and that are ready to implement in a relatively short time frame.”

Commercialization Efforts in the Wings

In 2021 Gadikota and her co-inventors filed a patent for the process they developed to capture carbon dioxide from air or emissions and convert it into calcium carbonate. They subsequently won an NSF Innovation Corps grant, which helps academic inventors learn about entrepreneurship and the ins and outs of founding a startup business. To date, they’ve talked to 120 companies about the need for their technology.

“We have many industry partners who are very interested and intrigued by this technology,” Gadikota says. “We’ve also received a lot of encouragement from them. We’ve done the groundwork: getting grants, filing patents, trying proof-of-concept. We’ve de-risked the space so much that industries are showing a lot of confidence. They’re very keen to allocate time, effort and resources so they can collaborate with us on translating our technology to the market.”

Jackie Swift is a freelance writer for the Office of the Vice President for Research and Innovation.

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