Enhancing system understanding in CCUS development using causal loop diagrams

Carbon Capture, Utilization, and Storage (CCUS) systems comprise multiple interdependent subsystems that are often developed, assessed, and operated in isolation. Developing an integrated understanding of these interactions is essential for identifying risks, synergies, and coordination challenges during the early stages of CCUS deployment. This paper investigates the use of causal loop diagrams (CLDs) as a qualitative group model building approach for revealing cross-sectoral interdependences within local CCUS systems. Using the industrial ecosystem of Aalborg, Denmark, as an empirical case, the study maps causal relationships among emerging CCUS initiatives and associated resource flows, including electricity, heat, water, wastewater, and cooling. By integrating project-level CLDs into a system-level representation, the analysis identifies reinforcing and balancing feedback mechanisms that shape system behaviour over time, revealing both opportunities for system integration and risks of infrastructure pressure and lock-in. The findings demonstrate how CLDs can support early-stage strategic decision-making by facilitating shared system understanding, identifying leverage points across subsystem interfaces, and enabling reflection on coordination needs before major investments are committed. The paper contributes a context-sensitive, qualitative system perspective that complements existing CCUS planning approaches and supports the development of coherent and locally anchored CCUS strategies.