Publication Overview
The aim of this study was to bring together and review the research that has been undertaken in Europe, North America, Japan and Australia, to develop an understanding of how knowledge on deep saline aquifers has developed in recent years, in particular since the 2005 IPCC Special Report on CO₂ Capture and Storage (IPCC SRCCS). Emphasis was placed on the identification of knowledge gaps and priority areas for R&D activities.
Publication Summary
The starting point for the study was the knowledge gaps identified by the IPCC SRCCS, which were summarised in the study report as the following ten key points: 1. Current storage capacity is imperfectly known due to inconsistency in assessment methodologies, lack of data and gaps in global, regional and local estimates, particularly data from Africa, South America and large parts of Asia, although there are also many data gaps in OECD countries too. 2. Kinetics of trapping mechanisms and their long term impact on reservoir characteristics, particularly geochemical trapping need further investigation. 3. Improved coupled hydrogeological-geochemical-geomechanical numerical models would help to better predict the long-term fate of injected CO₂ in the subsurface and quantify potential leakage2 rates. 2 Within this overview, leakage is defined as the movement of CO₂ outside of the targeted storage formation. 4. Risks of CO₂ leakage from abandoned wells due to casing and cement degradation and the temporal variability and spatial distribution of leaks should be better assessed. 5. Quantitative methods to assess the risk of CO₂ leakage to human health and the environment are needed. 6. Improved monitoring technologies would be useful, such as a) better geophysical techniques for the quantification and resolution of CO₂ plumes in the subsurface, b) improved remote sensing and other cost-effective methods for temporally variable leak detection, c) methods for fault and fracture detection and characterisation of their leakage potential, and d) development of suitable long-term monitoring strategies. 7. Options for mitigation and remediation technologies for potentially leaking CO₂ need to be developed. 8. There is insufficient information on potential costs of CO₂ storage in aquifers, including regulatory compliance costs and monitoring requirements. 9. The regulatory and liability framework for CO₂ storage in aquifers is unclear or needs to be established, particularly with respect to decommissioning requirements and long-term liability. 10. Standardised approaches for verification and accounting of CO₂ storage are lacking.
