Model Benchmarking for Consequence Analysis of Atmospheric CO2 Releases

Carbon Capture and Storage (CCS) systems have emerged as a cost-effective mid-term strategy for mitigating CO2 emissions, with the number of CCS facilities rapidly increasing worldwide. Ensuring the safety and reliability of CCS infrastructure requires a thorough understanding of accidental release behaviour and accurate modelling of potential consequences. In this context, extensive validation of existing consequence assessment tools is essential to increase confidence in their predictive capabilities. Accordingly, the current work presents a thorough validation and benchmarking of three selected software tools, namely PHAST, EFFECTS, and OLGA. PHAST and EFFECTS are well-established consequence assessment tools, while OLGA is a dynamic multiphase flow simulator, originally developed for hydrocarbon transport, and recently adapted to simulate CO2 release source terms. The performance of the models implemented in the software codes was evaluated by comparing predicted parameters, such as mass flowrate, downwind dispersion concentration, and temperatures, with the corresponding observed parameters across a wide range of experimental datasets. These tests involved atmospheric releases of both liquid and supercritical CO2 from vessels and pipelines, considering both buried and above-ground configurations. The comparative analysis identifies each model’s strengths and limitations, particularly in reproducing the unique thermodynamic behaviour of CO2, including solid formation during rapid depressurization. The findings provide valuable guidance for improving model accuracy and reliability, ultimately supporting the safety of CCS operations and contributing to strengthening public trust in these emerging climate mitigation technologies.