Assessing environmental impacts from geological CO2 storage

Abstract For any project that is supported by a risk analysis, the assessment generally needs to evaluate the consequences of health, safety and the environmental (HSE) impacts, and geological CO 2 storage projects are no exception. To date, however, assessments of storage projects have focussed more on the performance of the storage reservoir in terms of its ability to contain the CO 2 or at least prevent its leakage to the surface or near-surface environment, rather than determine the potential impacts of leakage of CO 2 (and any gases such as H2S or radon that may be transported with the CO 2 ) on specific environmental targets. This situation has been dictated to some extent by the lack of information or data on the nature of the potentially broad range of environmental impacts that might arise from elevated levels of CO 2 in the environment. Thus, this paper provides input on two fronts: the results from (i) a scoping analysis of potential environmental impacts from a specific storage project, and (ii) a review of work being carried out on the potential environmental impacts that might be expected from geological CO 2 storage projects. Of the two cases considered as a basis for deriving limiting leakage of CO 2 from the geosphere, the CO 2 leakage to a potable aquifer provides the overall limiting case under the conditions considered in this study. The review of the current literature on potential environmental impacts indicates that information and data are lacking in a number of areas, to the extent that some prioritisation will be necessary to focus technical work on specific ecosystems in order to make significant progress in the short term.