In the event of a loss of containment of a pipeline, a release of supercritical carbon dioxide can spread at ground level over large areas, dependent on the pipeline operating conditions and release size.

Thornton Tomasetti have completed a suite of consequence modelling simulations employing computational fluid dynamics (CFD) methods, with the purpose of demonstrating the hazards associated with carbon dioxide pipeline rupture events, and providing information on the hazard ranges and potential impact of the releases.

A number of modelling parameters were subject to review, to provide information on the factors that can influence the hazard ranges.

• Ruptures of buried pipelines may produce craters, which affect the mixing and momentum close to the source depending on whether the release impinges on the walls / base of the crater. These local effects were found to have significant impacts on the concentration of the plume in the far-field.
• Formation of solid carbon dioxide in the release.
• The surrounding topography used for CFD modelling of pipeline ruptures is often simplified to idealised flat planes or simple sloped terrain. Carbon dioxide is denser than air and as such, topography plays a significant role in the shape and dilution of plume.

The concentrations and temperatures of the carbon dioxide, as well as the duration of impact, were assessed with distance from the release to provide information in the hazard ranges and the potential impact on personnel.

The results of the work demonstrate that the impact of the above parameters are non-trivial, and care is required in selecting appropriate methods of modelling releases to provide an understanding of the potential hazard range and impact area.