iii. Geologic Sequestration Trapping Mechanisms
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This mechanism involves the confinement of carbon dioxide in a gaseous state beneath a low-permeability cap rock. Analogous to the storage of natural gas in reservoirs, this trapping method relies on the impermeability of the cap rock to contain the carbon dioxide. |
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Solubility trapping entails the dissolution of carbon dioxide into a liquid medium, such as water or oil. By dissolving the carbon dioxide in these substances, the likelihood of its release is reduced, providing an additional means of containment. |
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In mineral carbonation, carbon dioxide undergoes a chemical reaction with minerals, fluids, and organic matter within a geologic formation. This results in the formation of stable compounds, predominantly calcium, iron, and magnesium carbonates, contributing to the secure sequestration of carbon dioxide. |
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The most effective approach often involves a synergistic combination of hydrodynamic trapping and solubility trapping. This dual mechanism offers a comprehensive solution, employing both the impermeability of cap rocks and the solubility of carbon dioxide in liquids to ensure robust subsurface storage. |