Moshi et al. (2025): The Influence of Sediment Properties on CO₂ Hydrate Sequestration in Sub-Seafloor Saline Sediments: A Review of Formation and Stability
Jennifer S. Moshi, Chaohua Guo, Fravian M. Marobo, Orgenes S. Moshi, IN: Energy & Fuels ,https://doi.org/10.1021/acs.energyfuels.5c01292
CO₂ hydrate storage in subseafloor saline sediments has shown promise through sediment-specific and sediment modification approaches aimed at maximizing hydrate formation, stability, and storage potential. However, the long-term storage efficiency is compromised due to the harsh conditions of the subseafloor saline sediments, such as overly high pressure and temperature conditions, fluctuation in salinity, sediment interactions, and sediment heterogeneity. Techniques, such as the use of inorganic emulsifiers, amino acids, and coatings with nanoparticles (NPs) or functionalized compounds, have revealed benefits in enhancing CO₂ hydrate formation, stability, dispersion, and nucleation, leading to improved storage capacity and long-term storage efficiency. In this work, the performance of sediment surface modification techniques in enhancing CO₂ hydrate formation efficiency, storage capacity, and long-term storage efficiency, such as surface roughening, nanotechnology-based modifications, chemical functionalization, electrokinetic methods, thermal treatment methods, and the factors that impair their effectiveness, was highlighted. Additionally, the roles of chemical additives, such as sodium chloride, surfactants, and polymers, in sediment modification for improved CO₂ hydrate storage were examined. Synergistic interactions among sediment surface roughening, NPs, and chemical additives to the interfacial tension reduction, induction time reduction, increased adsorption tendencies, and wettability change were presented. In addition, the review addresses challenges and potential remedies, synthesizing experimental data, simulations, and theoretical studies to advance the understanding of sediment-specific and sediment modification CO₂ hydrate storage. By consolidating existing knowledge, this work aims to guide CO₂ storage researchers, engineers, and policymakers in optimizing subseafloor saline sediments as viable CO₂ reservoirs, contributing to global carbon mitigation efforts.