CO₂ capture and conversion perspectives for a cleaner future

To date, most CO₂ capture and conversion processes have been developed in isolation, where the output of the capture process is purified, compressed CO₂, which can be used as the feedstock for the CO₂ conversion process. This is an energy intensive process and purified CO₂ stream still needs to be delivered to the location where it will be converted to the desired product, thus further increasing energy demand. Co-locating CO₂ capture and conversion into one reactive capture system would eliminate the need for transport and compression. Reactive CO₂ capture is an emerging process intensification approach for generating CO₂-derived products that hold the potential for energy savings.

In a recent perspective article, published in Joule, LLNL researchers and collaborators define “reactive capture” as the coupled and integrated process of capturing CO₂ from a mixed gas stream and converting it into valuable products without a separate process step to generate purified CO₂. The article introduces unique challenges to this emerging technology, while also describing the current strategies, the state of technology for reactive capture, and providing a roadmap to guide research toward realizing these potential benefits.

The researchers propose that the value proposition for reactive capture is the reduction of energy intensity and capital expense in the production of CO₂-derived chemicals and materials. They explain that while the field of reactive capturing is still just emerging, it is important to assess these technologies from a process- and system-level perspective so that showstoppers and scale-up challenges can be identified early in development, before the costs of pivoting become insurmountable. Additionally, the technology must progress in parallel with an eye toward ultimate use. For example, a viable system must operate for thousands of hours, preferably in a continuous mode that necessarily matches capture and conversion rates.

Finally, the team’s roadmap includes the early identification of critical risks to technology scale-up and deployment. Foreseeable risks can be mitigated if identified early enough in the development process—these include the suitability of the process for scale-up and the ability to scale the manufacturing of the required components while retaining the required performance. In certain cases, the processes can be re-designed, and materials can be changed, but these changes take time and must be undertaken early. Risk mitigation and demonstration under real-world conditions give the best chance for reactive capture to bring about carbon utilization at impactful scales.

This work was funded, in part, by the Lawrence Livermore Laboratory Directed Research Development (LDRD) program (19-SI-005).

[M,C. Freyman, Z. Huang, D., Eric B. Duoss, Y. Li, S.E. Baker, S.H. Pang, J.A. Schaidle, Reactive CO2 capture: A path forward for process integration in carbon management Author links open overlay panel, Joule (2023), DOI: 10.1016/j.joule.2023.03.013.]

–Physical and Life Sciences Communications Team