KVAL: GeoCarb – mineralization of CO2 in geopolymeric slurries to create net-zero emission building materials

Geopolymers are known as alternative environmentally friendly material to Ordinary Portland Cement (OPC). Geopolymers have 70-80 wt.% lower CO2 emission compared to OPC. As a follow up from unexpected lab results, the value proposition can be improved further based on discoveries that CO2 can be mineralized in geopolymeric slurries, building a case also as a Carbon Capture, Utilization and Storage (CCUS) technology. Depending on the chemical composition and reactivity level of the precursors, and temperature during the reaction, CO2 was utilized and transformed to a mineral with currently up to 4 wt.% of the geopolymer weight. The method is patent pending as per PCT/EP2020/083835, filed 30. Nov 2020. Being able to increase the CO2 intake and utilization efficiency from 4% to 10%, or even 20%, could lead to a net-zero emissions product, and significantly add to the investment case - justifying additional R&D and complexity. Unique selling points are formulated in relation to being sustainable, scalable, permanent, practical & safe and energy-efficient. The technology could serve as a platform to establish green building materials to mitigate CO2 emissions - supporting the overall geopolymer industry - as well as providing a credible carbon credit strategy for large-scale industry users. The spin-off company SafeRock AS has an exclusive license to the technology, working closely with UiS and Validé (TTO). Near-term risk mitigation emphasizes end-user validation and commitments, regulatory aspects and process efficiency. A positive qualification project will set the scene for an ambitious main R&D project to design, build and optimize a reactor, and upscale the process by adjusting key operating parameters. As result of this project, we found out that to mineralize CO2 in our geopolymers, direct CO2 injection (in gas status) into the geopolymers creates challenges and upscaling the process is not viable. However, by dissolving CO2 in water or the hardener phase, CO2 was mineralized more efficiently, homogenously distributed, prevented shrinkage of the geopolymers and was operationally viable to be upscaled.

Several sets of experiments and analysis were carried out; Such as, preparation of the slurries using a specific recipe for our precursors and two separate hardeners. Next step was the carbonation of the slurries. The two methods that were applied were direct CO2 gas injection into the slurry and injection of CO2 into the water from the recipe and addition of the soda water as part of the ingredients. For the analysis of the outcome, X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) were carried out on each set of the experiments and also the neat samples (Without CO2 addition) to do proper comparison. The results show high capability for the geopolymers to store CO2 via mineralization. Formation of new carbonate minerals was the proof for that which was observed via XRD and SEM. Moreover, it was discovered that the addition of CO2 to our system mitigates some severe errors in our previous recipes such as formation of cracks and fissures and shrinkage.