Toward the Practical Economic Evaluation of Enhanced Carbon Dioxide Storage in Deep Saline Aquifers

Carbon dioxide (CO2) capture and storage (CCS) is proposed as a potential alternative technique for reducing large-scale greenhouse gas emissions. Deep saline aquifers have attracted tremendous attention because they have the largest potential of all possible subsurface storage sites. The storage efficiency is significantly low due to issues such as viscous fingering and gravity segregation. Several enhanced CO2 storage (ECS) methods, such as water-alternating-gas injection, CO2 foam injection, and nanoparticle-assisted injection, have been proposed to improve storage efficiency and overcome limitations. However, the economic value or its evaluation methods have not been discussed or reported. In this study, we reviewed ECS methods proposed so far and established a concept of the benefits obtained by ECS. Furthermore, we proposed a novel method for evaluating the economic value of ECS methods by providing a criterion for the acceptable cost of ECS implementation, whereas conventional approaches estimate only the unit cost of reducing CO2 emissions. The sensitivity analysis under various scenarios, including carbon pricing, was conducted based on publicly available data from the Quest CCS project. The results demonstrated that the acceptable cost for ECS significantly varied depending on the operational and political scenarios. In practice, the application of the ECS method requires careful consideration of various factors and conditions. Those results will contribute to the feasibility study for the ECS application and advance the ECS method from laboratory-scale research to the field pilot stage.