(Invited) Carbon Neutral Engineering for Water-Energy Nexus : Electrochemical Ion Separation (EIONS) and Water Electrolysis
Authors: Yoon Jeyong 
Published: September 2023

The world is facing a climate crisis, and carbon neutrality is an emerging solution. Carbon emissions, which must be reduced to achieve carbon neutrality, have their roots in the Industrial Revolution. Engineering systems that have developed since the Industrial Revolution is based on the exploitation of fossil fuels, meaning that there are limitations to reducing carbon emissions using this framework. Therefore, humanity needs a new engineering framework called Carbon Neutral Engineering, which is defined as an overall engineering system that redefines theory, technology, and production systems in various fields to achieve carbon neutrality [1].
In this presentation, I would like to talk about Carbon Neutral Engineering technologies for water-energy nexus. The water-energy nexus can be redefined under the Carbon Neutral Engineering concept because of the renewable energy. The relationship between water-based technology and renewable energy will be discussed representing Electrochemical Ion Separation (EIONS) and water electrolysis technology.
EIONS is a next-generation separation technology that can respond to the electrification demands of a carbon neutral society. Compared to existing heat and pressure-based separation technologies, EIONS has high selectivity, and thus can separate target materials with high purity in just a few steps [2]. In addition, since EIONS is operated mainly by electricity, it is energy efficient and eco-friendly in a renewable energy-based environment. EIONS can be applied to desalination of seawater or brackish water, recovery of valuable resources such as lithium, softening of hard water, removal of nutritive salts, and groundwater treatment [3]. Our research group has been conducting various research on EIONS technologies such as capacitive deionization (CDI), electrochemical lithium recovery (ELR), and desalination battery (DB).
Water electrolysis is a technology that produces hydrogen, an important energy source for a carbon neutral society. Hydrogen can not only respond to the intermittency of renewable energy, but also is an eco-friendly energy that does not emit greenhouse gases when renewable energy-based electricity is used to produce it. Anion exchange membrane (AEM) water electrolysis is a next-generation technology that has the structural advantages of polymer electrolyte membrane (PEM) water electrolysis and the operating environment of alkaline water electrolysis. Our research group proposed the introduction of electrodeposition technology for high-performance catalysts of AEM water electrolysis with high current density even in distilled water.
In conclusion, under Carbon Neutral Engineering, water-based technologies can be combined with energy technologies, which can be seen as a new interpretation of the water-energy nexus. This convergence technology will provide insight in the transition to a new era and suggest a new direction for technological development.

References

[1] Joo, H., Yoon, J. (2022). Basic Concept of Carbon Neutral Engineering in the Chemical Industry to Overcome the Climate Crisis, Korean Industrial Chemistry News, 25(2), 34-39.
[2] Yoon, H., Lee, J., Kim, S., & Yoon, J. (2019). Review of concepts and applications of electrochemical ion separation (EIONS) process. Separation and Purification Technology, 215, 190-207.
[3] Kim, K., Candeago, R., Rim, G., Raymond, D., Park, A. H. A., & Su, X. (2021). Electrochemical approaches for selective recovery of critical elements in hydrometallurgical processes of complex feedstocks. Iscience, 24(5), 102374.

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