© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. To quantitatively assess the risks associated with Carbon Capture and Storage (CCS) technology, a better understanding of the dispersion characteristics of CO2 released from a high-pressure pipeline is necessary. The dispersion process is complicated as CO2 is denser than air, and the Joule-Thomson effect causes sharp drop of the temperature. In this study, computational fluid dynamics (CFD) technique was used to investigate the CO2 dispersion. The CFD model is validated by simulating a full-size blasting test. The influence of topography and low temperature at the release source on the dispersion of CO2 released from buried CO2 pipelines over complex terrain types was studied. This study provides a viable method for the assessment of the risks associated with CCS.