Conceptual models for CO2 release and risk assessment: a review.

Carbon capture and storage (CCS) is a technology for mitigating the contribution of fossil fuel emissions to global warming. The technology is based on capturing carbon dioxide (CO2) from point sources and storing it in geological formations in such a way that is does not enter the atmosphere. CCS requires the transport of CO2 from source to sink. This can involve one or a combination of transport media: truck, train, ship or pipeline. Transport by pipeline is the preferred option for transporting large quantities of CO2 over long distances. The majority of CO2 pipelines are in the USA and Canada, along with substantial in-field pipework for Enhanced Oil Recovery (EOR) projects (Kelliher et al, 2009, Kadnar, 2008). The USA experience cannot be easily applied to other regions or situations, because the CO2 pipelines are located in areas with low population density. In general, as stated in the report of the IPCC on CCS (IPCC, 2005), there is a lack of knowledge regarding the safety of pipeline transmission of CO2 in densely populated areas. The aim of this paper is to review the current state of the art in the analysis of risk for CO2 transport by pipeline. A brief review is presented of current models for CO2 release, the assessment of impact from such release, and overall risk analysis. For a simple case study, a comparative analysis is presented of alternative models for the calculation of consequences. This comparison indicates that different assumption models and software lead to important differences in the calculation of consequences. One of the problems is the difficulty in comparing and assessing results due to lack of experimental data. Key unresolved problems and some directions for research needed are identified.