Within the Carbon Conversion Pathway, the Office of Fossil Energy’s (FE) Carbon Utilization Program focuses on the development of new catalyst materials, reactor designs, and methods to economically convert CO2 into useful chemicals. This program is implemented by the National Energy Technology Laboratory, which oversees both internal and external projects. The current project portfolio includes approaches that generate a wide variety of products including carboxylic acids, hydrocarbons, CO/syngas, alcohols, and solid carbons.

A significant challenge faced for the conversion pathway is that CO2 is a very low-energy molecule. The conversion of CO2 requires significant energy inputs to activate the CO2 along with catalysts to speed chemical reactions and selectively generate desired products. Catalyst development, design, and optimization is a common element among projects conducted within the Carbon Conversion Pathway. The approaches being pursued within the program fall into four general categories:

  • Thermochemical: Energy is provided in the form of heat (and pressure) and the reaction is often driven by a catalyst.
  • Electrochemical: Energy is provided in the form of electricity and catalyzed reactions take place in an electrochemical cell.
Lab-scale electrochemical cell stack to convert CO2 to alcohols
Lab-scale electrochemical cell stack to convert CO2 to alcohols (1)
  • Plasma-mediated: CO2 is activated by energetic electrons instead of heat and the reaction is often driven by a catalyst.
  • Biocatalysis: CO2 conversion processes are mediated by microbes and accelerated by enzymes.
Schematic representation of a biocatalytic conversion approach to generate acetate from CO2

While many current systems are driven through any of the previous approaches, upcoming research is constantly investigating new and innovative methods. These systems can hybridize established systems, such as by combining the advantages of electro- or thermo-based approaches with plasma or biocatalysis. Other systems are reassessing how the CO2 is delivered to the conversion system. Researchers are exploring the concept of “reactive capture” by process intensification which combines capture capture and utilization into one step resulting in large improvements in energy costs and capital investment of the overall process. The conversion pathway is one of the most dynamic R&D landspaces especially for early TRL development.

 

[1] Jiao, F. 2019. Electrochemical Conversion of Carbon Dioxide to Alcohols. US DOE/NETL Annual Meeting, Carbon Capture and Utilization, August 2019, Pittsburgh, PA. View presentation

[2] Gulliver, D. 2019. Electrode-Driven Microbial CO2 Utilization. US DOE/NETL Annual Meeting, Carbon Capture and Utilization, August 2019, Pittsburgh, PA. View presentation