(23b) Consequence Analysis of the Satartia Carbon Dioxide Release

Decarbonizing the United States industrial economy will require gigaton-scale carbon dioxide capture and storage efforts. This will include the formation of geological storage hubs with numerous industrial sources transporting CO₂ to dedicated storage sites. Although transport of liquefied CO₂ by truck or rail car is feasible, pipeline transport is usually the safest and most economical option.

Currently, there are approximately 5,000 miles of CO₂ pipelines in operation in the US. Additional pipeline systems are in the planning stage to service geological injection sites undergoing permitting and design. However, pipeline construction plans have been met with public opposition. Some climate activists have argued that carbon dioxide pipelines pose unacceptable risks to the public. An example of this risk frequently cited is the carbon dioxide pipeline failure that occurred on February 22, 2020, in Satartia, Mississippi. The Satartia event resulted in the release of 5,000 m³ of CO₂, which sent 49 people to the hospital and required the evacuation of about 300 residents. However, this release was unusual due to the unfortunate location of the pipeline failure, which resulted in downward dispersion of the dense vapor. The steep terrain channeled the dense vapor directly into the community and local roadways owing to the topography surrounding the release.

The consequence evaluation presented here shows that the topography of the release site played a major role in the dense cloud dispersion behavior and was a major causal factor in the exposure risk. Integral models of dense gas dispersion on flat terrain significantly underestimate the exposure risk. A more realistic understanding of the exposure risk is obtained by considering the behavior of a dense gas plume descending down sloped terrain while channeled by ravine walls towards a target population. This study further supports our earlier recommendations: 1) consider the topography associated with carbon dioxide pipeline routing, especially in locations at an elevation above a community; and 2) if possible, avoid locating a carbon dioxide pipeline in terrain where ground movement hazards are likely.