Conclusions All the important risks for CGS projects have been identified, and the R&D community and industry have found solutions to most, if not all, of these. Because every storage site will be unique, each site will need to be individually qualified, based on its own specific profile of subsurface and surface properties, and using the best available technology and solutions as they inevitably evolve and improve. Standardized work flows that promote sitespecific qualification will make this task more effective, while avoiding the traps of prescriptive, static, technical solutions. The key features of site qualification will be transparency and complete, auditable records of the permit approval process, such that public confidence can be earned and maintained. Very similar industrial activities in the EOR industry, injecting CO2 in large quantities (cumulative injection ca. 600 million tons CO2) in the underground to increase oil production, have generated high confidence in key parts of the systems required for CGS in deep saline formations for the purpose of reducing GHG emissions. Indeed, permanent disposal of gases by injecting them into the subsurface has been practiced for over 15 years in Canada, and CO2 permanent storage by injecting large volumes into a deep saline formation has been practiced at Sleipner since 1996. These projects have shown that although the CGS strategy is neither failure-free nor totally without risk, industry and regulators have the necessary solutions to manage risks effectively. Nonetheless, scale up of this strategy, from the current situation of a few projects to hundreds of projects, remains a challenge. DNV is actively developing and promoting compact, standardized evaluation tools for the site screening phase and that have the potential to be applied to screening thousands of candidate sites, so that they can
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be ranked according to a relatively sparse, but indicative, set of site characteristics. Once candidate sites have been selected for more detailed exploration and site surveying, a set of more advanced and detailed evaluation processes will potentially lead to application for a storage permit. Fit-for-purpose regulatory capacity and frameworks are being developed and will be fully operational in the near future. Proper site performance will be verifiable for sites that have carefully designed and installed fit-for-purpose monitoring systems that follow the evolution of the site throughout its lifecycle. DNV anticipates a growing need for independent verification of monitoring systems and data to maintain public confidence in site integrity. Although final site closure is a challenge that is still 20 years away, the entire community of CGS stakeholders is actively preparing for this phase. Much of the experience from sealing and abandoning wellbores in the oil and gas industry will be directly applicable. CO2 geologic storage can be made very safe, given that the main safety barrier is a kilometer (or more) of the Earth’s crust, and that subsurface geoscience and engineering are applied using the most effective risk management methods, originally developed for a range of industrial activities and carefully adapted to fulfil the special needs of CGS.