Carbon Capture and Utilization: What’s Next?

Capturing the greenhouse gas carbon dioxide (CO₂) from coal- or gas-fired power plants and other large industrial emission sources will be critical to meeting climate goals. But doing so comes at a substantial cost—mostly in the form of parasitic energy load of these processes and also from the large capital requirements for such technology.

What innovations are needed to make carbon capture andutilization (CCU) more economically feasible? A recent Mission Innovation workshop about CCU addressed this question; more than 200 invited experts from around the world attended the workshop. Through the Mission Innovation initiative, 22 countries and the European Union (EU) promote the development of clean energy technologies; these countries and the EU plan to double their research and development (R&D) investments over the next 5 years. The U.S. Department of Energy invited three experts from RTI International to participate in the panel discussions.

Capturing the greenhouse gas carbon dioxide (CO₂) from coal- or gas-fired power plants and other large industrial emission sources will be critical to meeting climate goals. But doing so comes at a substantial cost—

Innovation in Solvent-Based CO₂ Capture

Of the several carbon capture solutions currently in development, solvent-based processes are closest to being ready for full-scale deployment—and several large-scale demonstrations are operating. Over the last several years, substantial progress has been made to lower the amount of energy required (and therefore the cost) for each ton of CO₂ captured. The current amount is now pushing towards approximately 2.0 gigajoule (GJ)/metric ton of CO₂—down from 3.6 GJ/metric ton, which had been considered the benchmark for years. This reduction has been accomplished with water-lean solvents. (RTI’s non-aqueous solvent [NAS] technology is one of them.) Modest gains in process efficiency will be possible with these solvents, but the field seems to be reaching diminishing returns on that front. Other remaining challenges relate to solvent stability and corrosivity, as well as to potential emissions through aerosols—all of which translate into operating and capital costs.

The panel focused on solvent based capture identified two primary research directions to reduce the cost of CO₂ capture even further:

1. Designing High-Performance Solvent Systems: In this area, it will be important to develop a synergistic understanding of the physical and chemical solvent attributes and the specific process features needed to fully utilize these next-generation solvents. New toolsets that connect molecular modeling with multiscale process modeling need to be designed. This will require close collaboration between chemistry and engineering disciplines. In addition, process intensification (e.g., through the use of new column internals or heat exchanger materials and geometries) has been identified as an area that can have a positive impact, especially on the capital costs of the process. The optimal process solution is expected to differ across industrial applications.
2. Mitigating Solvent Loss and Environmental Impact: This area will focus on developing a more comprehensive understanding of solvent losses and environmental impact, a knowledge gap that stems from the large variety of solvent degradation products and contaminants in the flue gas. Developing better analytical methods and models to predict solvent losses and environmental impact will be important to assess mitigation options.

The RTI team is determined to stay at the leading edge of these research directions. Stay tuned for the full Mission Innovation report that will be released within the next few months.