A Leap in Carbon Capture and Storage Technology: Using Costless Seawater to Store CO₂

Scientists develop a cost-effective yet efficient technique of storing toxic CO₂ in stable carbonate forms, using seawater

Indirect carbonation is popularly used as a technique to store CO₂ and reduce its levels in the atmosphere. But, this technique requires the use of expensive solvents, thus making its commercial usage impractical. Researchers in Korea have now demonstrated a cost-effective approach to indirect carbonation using costless seawater and an alkali industrial byproduct. This resulted in the effective storage of CO₂ along with the production of highly pure calcium carbonate (a useful compound).

Carbon dioxide (CO₂) is the most prevalent type of greenhouse gas and a major environmental threat. In an effort to reduce its levels from the atmosphere, scientists have come up with various techniques that can capture CO₂ and recycle them into useful forms (called the “carbon capture, utilization, and storage” or CCUS technology). Indirect carbonation is one such popular CCUS technique, which can be used to store CO₂ in the form of stable, useful compounds called “carbonates.” To do this, however, expensive chemical solvents are usually required, making the process economically infeasible.

To address the issue, a team of researchers at Korea Maritime & Ocean University, led by Prof Myoung-Jin Kim, came up with an innovative indirect carbonation technique, in which they replaced expensive chemical solvents with costless seawater. These findings are published in Chemical Engineering Journal. Prof Kim says, “Our main aim was to secure bring economic feasibility and efficiency to the indirect carbonation technology. To achieve this goal, we attempted to replace expensive chemical reagents used that are currently used as solvents with nearly costless seawater.”

In their experimental study, the scientists used seawater along with an alkali industrial byproduct called “cement kiln dust” (CDK) to conduct indirect carbonation. Their method resulted in the storage of a large amount of CO₂, in addition to a high yield of 99% pure calcium carbonate (CaCO₃)―a useful industrial compound. Not only this: this simple yet efficient method had a significant advantage over traditional acid-based methods, which require large amounts of alkali to bring up the pH to an optimal level. Prof Kim says, “By replacing chemical solvents with seawater, we could significantly reduce the cost that accounts for the largest part of the production cost to virtually zero, all of this while storing comparable amounts of CO₂ and simultaneously producing CaCO₃ of high quality.”

The scientists are optimistic that their method is a promising new way of including indirect carbonation as a CO₂ storage technique, especially in industries that are close to the ocean or have access to seawater. “If a cement manufacturing plant or a paper mill that emits a large amount of CO₂ and uses CaCO₃ as a raw material is located close to the ocean, this technology could be applied to reduce CO₂ emissions and reuse the produced CaCO₃ in the industrial process. In this way, we can turn industries into eco-friendly, economical plants!”

DOI: 10.1016/j.cej.2019.122180

*Corresponding author’s email: kimmj@kmou.ac.kr (M.-J. Kim)

About the author

Prof Myoung-Jin Kim received a PhD in Environmental Health Sciences from the University of Michigan, USA, in 1999. She is currently a Professor of Environmental Engineering at the Korea Maritime and Ocean University. Currently, her group is developing technologies to store carbon dioxide and produce calcium carbonate through indirect carbonation using industrial by-products and various solvents, including seawater and to economically recover high-purity magnesium compounds from seawater.