Towards defining reasonable minimum composition thresholds – Impacts of variable CO2 stream compositions on transport, injection and storage. (February 2022) - Rütters, Heike
Highlights: CCS cluster scenario investigated for impacts of variable CO2 stream composition & mass flow rate. To limit cross-chemical reactions control redox conditions in CO2 stream and at stream mixing. Silicate-cemented sandstones may be promising for storing CO2 streams with variable composition. No technical obstacles for handling CO2 streams with compositions & mass flow rates as in scenario. Recommendations derived for defining reasonable composition thresholds to be met by CO2 streams. Abstract: To set up recommendations on how to define "reasonable minimum composition thresholds" for CO2 streams to access CO2 pipeline networks, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the CCS chain. All investigations were based on a generic "CCS cluster scenario" in which CO2 streams captured from a spatial cluster of eleven emitters (seven fossil-fired power plants, two cement plants, one refinery and one steel mill) are collected in a regional pipeline network. The resulting CO2 stream (19.78 Mio t impure CO2 per year) is transported in a trunk line (onshore and offshore) and injected into five generic replicate storage structures (Buntsandstein saline aquifers) offshore. Experimental investigations and modeling of selected impacts revealed beneficial as well as adverse impacts of different impurities and their combinations. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the considered variable compositions and mass flow rates were observed. We recommend to define minimum composition thresholds for each specific CCS project through limiting i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of concentrations of critical impurities, and defining impurity combinations to be avoided.