Within the Carbon Mineralization Pathway, the Office of Fossil Energy’s (FE) Carbon Utilization Program focuses on the development of technologies that use CO2 to generate inorganic materials for use in the built environment. The 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 precipitated calcium carbonate, precast concrete products, multi-functional concrete, and construction materials.
One of the most significant challenges of utilizing CO2 is that it is a very low-energy molecule. For most applications, a form of energy (either thermal, chemical, or electrical) has to be added to convert CO2 into a different molecule to form products such as fuels and chemicals. In contrast, carbonates are even lower-energy than CO2, which minimizes the energy needed to form them. When CO2 is incorporated into the production of cement and aggregate, forming carbonates, it is not necessary to add energy to overcome thermodynamic constraints. This is important because the energy required to make large volumes of material could be extremely expensive, rendering the materials non-cost-competitive.(1)
Some of the other key advantages of mineralization-based carbon utilization include:
- Use in building materials represents an effective long-term storage solution for CO2
- Mineralization technologies/approaches can often use flue gas directly, bypassing costs associated with installing carbon capture systems on power and industrial facilities
- Construction materials represent a large potential market for CO2-based products if costs and other barriers to entry can be overcome
The graphic below illustrates how CO2 can be incorporated into concrete materials.