Speaker
Description
Anthropogenic CO2 emissions are the primary driver of climate change and ocean acidification, necessitating scalable and secure carbon capture and sequestration (CCS) approaches. CO₂ sequestration in marine sediments in the form of gas hydrates represents a promising long-term storage option due to high volumetric capacity and enhanced stability under deep-sea pressure and temperature conditions. In deep-sea Sediments, hydrate formation can immobilise CO2 and reduce leakage risks relative to dissolved or free CO₂ phases, leveraging natural hydrate stability zones in marine sediments. However, most laboratory studies have focused on idealised systems using deionised water or synthetic saline and model sands, leaving critical gaps in understanding hydrate formation kinetics in natural seawater and clay-rich subsea sediments. In this work, CO₂ hydrate formation kinetics were investigated in natural Krishna–Godavari Basin (KGB) sediments and seawater using pure CO2 gas at pressures of 3.0–7.0 MPa and ∼274.5 K, with and without biocompatible kinetic promoters (amino acids). Bentonite clay suspensions (0–7 wt.%) were used to approximate clay-dominated marine sediment environments.
Results demonstrate a strong dependence of hydrate formation on both clay content and the presence of promoters. Gas-to-hydrate (G-H) and water-to-hydrate (W-H) conversions increased with bentonite & KGB sediments concentration up to an optimum of 3 wt.%, rising from baseline seawater values of 20.21% to 52.82% and 14.64% to 27.88%, respectively. Beyond this concentration, conversion efficiencies declined, likely due to mass-transfer limitations and pore blockage. Combined KGB sediments-bentonite-amino acid systems also showed significant enhancements, with gas uptake increases up to 220% relative to bulk seawater.
This study provides the first comprehensive kinetic analysis of CO₂ hydrate formation in seawater containing natural clay minerals and environmentally benign promoters, offering insights into the sustainable deployment of hydrate-based CCS in clay-rich marine sediments.
Keywords: CO2 hydrate, Biodegradable promoters, Marine sediments, Sequestration, CCS
| Country | India |
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