Framework for CO2 impurity monitoring in CCUS infrastructure

• CO 2 impurity monitoring throughout the CCUS chain is essential for compliance, infrastructure protection, and supports decision making. • Conceptual framework of quality compliance control points at stakeholder transition interfaces. • Detailed evaluation of the risks and impacts associated with insufficient monitoring and control of CO 2 impurities. • The best monitoring candidates are found based on the variety and quantity of impurities present in the CO 2 stream. • A prediction is carried out based on the expansion of the CCUS industry and existing CO 2 specifications. As Carbon Capture, Utilization, and Storage (CCUS) expands, the need for safe and efficient CO 2 transport becomes increasingly important. Effective monitoring of CO 2 impurities is essential for maintaining system integrity and ensuring regulatory compliance across the CCUS chain. However, no standardized approach for impurity monitoring currently exists, and specifications vary depending on the project and transport method. This study identifies key stages in the CCUS process where impurity monitoring is critical. The impurity thresholds defined by the Northern Lights and Porthos projects are assessed in terms of corrosion mitigation, minimization of energy requirements, protection of human and environmental safety, and preservation of storage integrity. A conceptual framework is proposed to underscore the importance of CO 2 quality compliance at points of ownership handover, where decisions are determined based on measured impurity concentrations. The evaluation of impurities shows that impurities can significantly impact transport safety, efficiency, and storage performance, justifying the need for defined concentration limits. The findings suggest a risk-informed monitoring approach, where the frequency and precision of measurement are guided by the potential impact of each impurity, with H 2 O highlighted as a critical case requiring high-frequency monitoring. A comparative analysis of available sensing technologies reveals that no single method can detect all impurities listed in the CO 2 specifications. Instead, a combined monitoring strategy is proposed to meet specification requirements. As CCUS deployment accelerates, effective impurity monitoring will be essential to support regulatory compliance, taxation frameworks, operational control, and the development of secure and scalable CO 2 transport networks.