Researchers have created an electrochemical reactor that could significantly lower the energy usage and costs associated with direct air capture, which is the process of removing carbon dioxide from the air.
A team at Rice University has introduced an electrochemical reactor that shows promise in greatly reducing the energy needed for direct air capture, particularly the extraction of carbon dioxide from the atmosphere.
This innovative reactor design may help address critical climate and environmental challenges by facilitating more effective and adaptable carbon dioxide reduction methods.
A study published in Nature Energy outlines this specialized reactor, featuring a modular three-chamber design with a meticulously designed porous solid electrolyte at its center. Haotian Wang, a chemical and biomolecular engineer at Rice University who has been exploring industrial decarbonization and energy solutions, described the research as a “significant achievement in extracting carbon from the air.”
“Our findings open up possibilities for making carbon capture more affordable and feasible across various sectors,” stated Wang, who is the principal author of the study and an associate professor of chemical and biomolecular engineering.
The reactor has achieved relevant rates of regenerating carbon dioxide from carbon-containing fluids. Its performance indicators, such as long-term durability and ability to adapt to different cathode and anode reactions, highlight its potential for widespread industrial application.
“A key advantage of this technology is its versatility,” Wang noted, explaining that it can work with various chemistries and also produce hydrogen simultaneously. “Hydrogen production alongside direct air capture could lead to significantly reduced capital and operational expenses when manufacturing net-zero fuels or chemicals.”
This new method stands as an alternative to high-temperature processes often used in direct air capture, which typically filter carbon dioxide from a mixed gas stream through high-pH liquids. This initial step captures the carbon and oxygen in the gas molecules, binding them to other compounds in the liquid—a process that varies in bond strength based on the chemicals employed. The subsequent step involves reclaiming the carbon dioxide from these solutions, which can be achieved through heat, chemical reactions, or electrochemical methods.
Zhiwei Fang, a postdoctoral researcher at Rice and co-first author of the study, explained that traditional direct air capture methods frequently rely on high-temperature techniques to regenerate carbon dioxide from sorbents, the agents used to filter out the gas.
“Our approach centers on utilizing electrical energy rather than heat to regenerate carbon dioxide,” Fang mentioned, emphasizing that this method has several benefits, including operating at room temperature, requiring no additional chemicals, and producing no harmful byproducts.
Different sorbents used to trap carbon dioxide carry their own pros and cons. Amine-based sorbents are popular as they generally form weaker bonds, making it easier to extract carbon dioxide from solutions, yet they are notably toxic and unstable. Basic water-based solutions, like those using sodium hydroxide or potassium hydroxide, represent a more environmentally friendly option but necessitate much higher temperatures for carbon dioxide recovery.
“Our reactor efficiently separates carbonate and bicarbonate solutions, generating alkaline absorbents in one chamber while producing high-purity carbon dioxide in another,” Wang explained. “Our unique method optimizes electrical inputs to effectively control ion movement and mass transfer, reducing energy demands.”
Wang hopes this research inspires more industries to adopt sustainable practices and helps propel the movement towards a net-zero future. He noted that this project, along with others from his lab, reflects Rice University’s commitment to innovative solutions for sustainable energy.
“Rice is the ideal place for anyone passionate about sustainability and energy innovation,” Wang concluded.
Other contributors to this study include former Rice postdoctoral researcher Xiao Zhang and Rice doctoral graduates and past postdoctoral scientists Peng Zhu and Yang Xia.
This research received funding from the Robert A. Welch Foundation (C-2051) and the David and Lucile Packard Foundation (2020-71371).
