Engineers develop new carbon capture technology

Engineers at Rice University have developed a groundbreaking technology that has the potential to significantly reduce the cost of capturing carbon dioxide from various emissions sources. This innovation, described in a study published in Nature, involves an electrochemical reaction powered by electricity to directly remove carbon dioxide from flue gas and even the atmosphere using water and oxygen. This advancement could revolutionize the field of direct air capture, which currently has only 18 operational plants globally, and make it a viable solution for mitigating climate change.

Unlike conventional carbon-capture systems that typically involve a two-step process using high-pH liquids to separate carbon dioxide from mixed-gas streams and then regenerate it through heating or low-pH liquids, this new system developed by the lab of Haotian Wang eliminates the need for chemicals or extreme temperatures. Traditional methods require temperatures ranging from 100 to 900 degrees Celsius (212 to 1652 degrees Fahrenheit), whereas the new technology can operate simply by being plugged into a power outlet.

The elimination of chemical consumption and production, as well as the avoidance of heating and pressurization requirements, make this innovative carbon-capture system highly efficient and cost-effective. It has the potential to support industries striving to meet evolving greenhouse gas standards and contribute to the emerging energy-transition economy. By offering a more accessible and sustainable solution for carbon dioxide capture, this development could play a significant role in combating climate change.

Credit: Rice University

Unlike existing carbon-capture technologies that rely on large-scale, centralized infrastructure, the system developed in the Wang lab offers a scalable, modular, and point-of-use concept that can be easily adapted to various scenarios. This flexibility is a significant advantage of the technology.

According to Haotian Wang, the system can be scaled up for industrial applications in power plants and chemical plants. However, what makes it truly remarkable is its potential for small-scale use. It can be utilized in everyday settings, such as offices, allowing individuals to directly capture carbon dioxide emissions. Moreover, the system can even be employed in unique scenarios like injecting concentrated carbon dioxide into greenhouses to enhance plant growth. Wang shared that they have received interest from space technology companies looking to utilize the technology on space stations to remove carbon dioxide exhaled by astronauts.

The reactor developed by Wang and his team has demonstrated exceptional efficiency in capturing carbon dioxide. It can continuously remove over 98% of carbon dioxide from simulated flue gas using a relatively low amount of electricity. As stated by Peng Zhu, a lead author on the study, the electricity needed to power a 50-watt lightbulb for an hour can yield 10 to 25 liters of high-purity carbon dioxide.

Furthermore, Wang emphasized that the process has either no carbon footprint or an extremely limited one when powered by renewable electricity sources like solar or wind. This aligns with the increasing cost-effectiveness of renewable energy, making the system even more promising in terms of sustainability.

Peng Zhu (left) and Haotian Wang beside their carbon-capture device prototype. Credit: Jeff Fitlow/Rice University

The reactor developed by the Wang lab comprises a cathode that facilitates oxygen reduction, an anode that performs the oxygen evolution reaction, and a compact yet porous solid-electrolyte layer, enabling efficient ion conduction. In earlier versions of the reactor, the focus was primarily on carbon dioxide utilization, where pure liquid fuels like acetic acid and formic acid were produced.

During the research process, Peng Zhu, a member of the team, observed the flow of gas bubbles along with the liquids from the reactor’s middle chamber. Initially, this phenomenon was not given much attention. However, Zhu noticed a direct correlation between the flow of bubbles and the amount of current applied.

Further investigation revealed that an alkaline interface generated at the cathode side during reduction reactions interacted with carbon dioxide molecules, resulting in the formation of carbonate ions. These carbonate ions then migrated into the solid-electrolyte layer of the reactor. Simultaneously, protons produced from water oxidation at the anode side combined with the carbonate ions, leading to a continuous flow of high-purity carbon dioxide.

Wang noted that this phenomenon was serendipitously discovered during previous studies. The researchers subsequently fine-tuned and optimized the technology for the new application described in the project. The development of this electrochemical device has been a result of years of dedicated work, emphasizing the importance of patient observation, continuous exploration, and the willingness to explore phenomena that may not initially align with the experimental framework.

This accidental discovery highlights the significance of scientific curiosity and the value of investigating unexpected phenomena, leading to breakthroughs and advancements in technology.

Source: Rice University

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