Tohoku Univ. Technology ：Enhanced CO₂ Geological Storage and Mineralization Using Rock Dissolution by Biodegradable Chelating Agents：T22-272

Safe, Secure, and Efficient CCS: A Key to Decarbonization

In recent years, CO₂ geological storage using mafic and ultramafic rocks—such as basalt and peridotite, which are rich in calcium and other metal elements that react with CO₂ to form carbonate minerals—has garnered global attention as a means of reducing atmospheric CO₂, a major contributor to global warming. However, subsurface environments for CO₂ storage are typically low in temperature and therefore have limited reactivity. Additionally, the amount and connectivity of pores as well as permeability of the subsurface rocks are not always sufficient, presenting significant challenges that require innovative technological solutions. In storage methods that involve dissolving CO₂ in water, the use of seawater is preferable. However, during the storage process, it is also necessary to temporarily suppress the reaction between metal ions in seawater and CO₂ until the CO₂ is securely stored. This invention promotes CO₂ geological storage and mineralization by using biobased, biodegradable chelating agents that enhance mineral dissolution and capture metal ions. By dissolving minerals in subsurface rocks using the chelating agents, the amount and connectivity of pores (CO2 storage capacity) increase, and the permeability (CO₂ injectivity) is also improved. Furthermore, when CO₂-charged seawater containing the chelating agents is injected into subsurface rocks, it becomes possible to simultaneously store both CO₂ and the metal ions required for carbonate mineral formation with creating additional rock porosity.

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