Global Geological CO2 Storage: A Comparative Review of Project Experience, Economics, and Long-Term Stewardship

Quantitative comparisons of geological CO2 storage projects often compare quantities, assets, operation period, and legal obligations that relate to different services. This critical integrative review analyzes nineteen selected geological CO2 storage projects in the United States, Canada, Norway, continental Europe, Africa, Australia, Japan, China, Germany, and Iceland. The review uses explicit project-level inclusion criteria, a claim-based hierarchy of sources, and qualitative coding for physical setting, quantity basis, development architecture, economic description, and stewardship. Its contribution is an applied framework for project comparison based on the classification of evidentiary claims into five decision categories instead of a universal ranking of projects. The comparison reveals that design capacity, contracted capacity, actual injection, cumulative stored mass, and research campaign volume cannot be compared without records of operation and consistent definitions. Project experience also demonstrates the differences between subsurface dynamics and economic implications: pressure response affects development choice, monitoring quality affects evidentiary requirements for conformance and closure, and infrastructure ownership affects interpretation of disclosed expenditures. A storage-only economic comparison is possible only when the asset boundary, quantity boundary, reporting date, project maturity, and allocation of responsibility are explicitly defined. Financial assurance, post-injection stewardship, and transfer of responsibility in North America, Norway, continental Europe, and Australia are also jurisdiction-dependent and permit-dependent. The contribution of the review is a qualitative project comparison framework for the selection of analogous projects and the identification of needs for new appraisals, cost allocation, contract evidentiary support, or verification of closure requirements. The review does not evaluate project costs, estimate annual rate from cumulative injection, or provide representative global census.