Carbon Dioxide Sequestration via Gas Hydrates: A Potential Pathway toward Decarbonization

Climate change is known to be dominantly caused by the increased concentration of greenhouse gases in the atmosphere, in particular CO2. To prevent excessive accumulation of CO2 in the atmosphere and the perturbation of natural carbon cycles, carbon capture and sequestration (CCS) is urgently needed. In this review, a brief overview is provided for both biotic and abiotic CO2 sequestration pathways. Special focus is given to sequestration approaches pertaining to clathrate hydrates. CO2 hydrate, a solid compound made of molecular CO2 enclathrated in crystalline lattices formed by water molecules, is an attractive option for long-term CO2 sequestration due to its higher density than seawater, stability below moderate oceanic/permafrost depths, low susceptibility to fluid flow perturbation when formed in sediments. This review compiles and summarizes the research efforts made on CO2 sequestration as hydrates. Various approaches of CO2 sequestration via gas hydrates are discussed, including storage in seawater, sediments under the sea floor, permafrost regions, methane hydrate reservoirs via CO2-CH4 exchange, and depleted gas fields. The technical feasibility and potential storage capacity of these approaches are analyzed. Finally, the key scientific challenges and prospects are identified and highlighted. Issues related to economics, scale-up, and relative attractiveness versus non-hydrate methods are touched upon but are not the focus of this work.