CO2 geological storage safety assessment: methodological developments

Abstract : Carbon dioxide capture and geological storage is seen as a promising technology to mitigate greenhouse gas atmospheric emissions. Its wide-scale implementation necessitates demonstrating its safety for humans and the environment. We have developed a generic approach to provide references for safety assessment of CO2 storage. It is composed of a series of simple tools for identifying risk scenarios, modelling risk events and exposure. It incorporates a rigorous management of uncertainty, distinguishing between variability and knowledge incompleteness. We applied this approach on a case study in the Paris Basin. This demonstrates how it delivers conditions mixing qualitative and quantitative elements for guaranteeing safety. This approach is flexible; it can be used for various sites and with various amounts of data. It can be carried out in a time-efficient manner at various stages of a project. In particular, it provides an operator or an authority with safety indicators in an early phase or for reviewing a risk assessment. Though not a complete risk assessment workflow, it thus partly compensates for the current lack of commonly acknowledged assessment methods or safety standards for CO2 geological storage.