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CO2 CAPTURE AND SEQUESTRATION BY GAS HYDRATES: AN OVERVIEW OF THE INFLUENCE AND CHEMICAL CHARACTERIZATION OF NATURAL COMPOUNDS AND SEDIMENTS IN MARINE ENVIRONMENTS
Due to the rising atmospheric carbon dioxide levels driven by human activity, extensive scientific efforts have been dedicated to developing methods aimed at reducing its concentration in the atmosphere. A novel approach involves using hydrates as a long-lasting reservoir of CO2 sequestration. This review provides an initial overview of hydrate characteristics, their formation mechanisms, and the experimental techniques commonly employed for their characterization, including X-ray, Raman spectroscopy, cryoSEM, DSC, and molecular dynamic simulation. One of the main challenges in CO2 sequestration via hydrates is the requirement of high pressures and low temperatures to stabilize CO2 molecules within the hydrate crystalline cavities. However, deviations from classical temperature-pressure phase diagrams observed in natural and engineered environments can be explained by considering that hydrate stability and formation are primarily governed by chemical potentials, not just temperature and pressure. Activity, which reflects concentration and non-ideal interactions, greatly influences chemical potentials, emphasizing the importance of solution composition, salinity, and additives. In this context the role of promoters and inhibitors in facilitating or hindering hydrate formation is discussed. Furthermore, the review presents an overview of the impact of marine sediments and naturally occurring compounds on CO2 hydrate formation, along with the sampling methodologies used in sediments to determine the composition of these natural compounds. Special attention is given to the effect and chemical characterization of dissolved organic matter (DOM) in marine aquatic environments. The focus is placed on the key roles of various natural occurring molecules, such as amino acids, protein derivatives, and humic substances, along with the analytical techniques employed for their chemical characterization, highlighting their central importance in the CO2 gas hydrates formation.
TOWARDS HYDRATE-BASED CO2 STORAGE IN MARINE ENVIRONMENTS: SALINITY EFFECTS IN CO2-H2O BINARY SYSTEMS
TOWARDS HYDRATE-BASED CO2 STORAGE IN MARINE ENVIRONMENTS: SALINITY EFFECTS IN CO2-H2O BINARY SYSTEMS
Hydrates have recently come to the forefront because of their importance for the environmental impact and subsurface exploration. However, the conditions that affect their stability, particularly in the marine environment, are not yet fully understood. This study presents a static model on a global scale to assess CO2 hydrate stability. This analysis allowed evaluating the effects of salinity, sea water depth and geothermal gradient changes on CO2 hydrate stability also taking into account the thickness of the porous media. The results indicate that shallow water depth and low geothermal gradient favour the formation of CO2 hydrates. Furthermore, this modelling suggests that the actual salinity values rather than assuming constant values significantly improves the accuracy of stability predictions. A focus analysis was performed in the polar regions, where environmental conditions are most favourable for CO2 hydrate formation. The results provide a comprehensive global understanding of CO2 hydrate formation and optimal conditions, facilitating future local-scale applications.
CO2 STORAGE IN MARINE ENVIRONMENTS: SALINITY EFFECTS IN CO2-H2O BINARY SYSTEMS
This study investigates CO2 hydrate formation in marine environments using controlled experiments in pure water, 3 wt% NaCl, and 4 wt% NaCl solutions. Gas uptake decreased from 31.51 % in pure water to 13.97 % and 5.30 % in 3 wt% and 4 wt% NaCl solutions, respectively, as well as formation density (from 19.36 kg/m3 to 8.71 kg/m3 and 3.61 kg/m3). A non-linear effect was observed wherein 4 wt% NaCl solutions with slightly higher hydrate formation than 3 wt% under certain conditions, suggesting complex interdependencies between salinity, pressure and temperature. The pressure decline rate (ΔP/Δt) varies with pressure and salinity, demonstrating a direct correlation between formation pressure, water conditions and hydrate growth kinetics. Stability tests conducted at 65 bar in 4 wt% NaCl solutions confirmed CO2 hydrate persistence for over 10 days, reinforcing the feasibility of hydrate-based carbon sequestration in marine settings and providing critical insights for optimizing CO2 storage in deep-sea environments.
https://doi.org/10.1016/j.geoen.2025.214332
Carbon capture and storage as gas hydrates: characterization and optimization of CO2-hydrates formation
Poster communication with flash presentation present at the conference “Science for the Planet”- Campobasso, 22nd-25th June 2025.
Lorenzo Remia was also awared as best poster flash presentation.
CO2 captures and sequestration by gas hydrates in marine environments: chemical characterization of natural organic compounds, sediments and their influences.
Poster communication of the CO2-RESTO results at the XXI Congresso Nazionale della Divisione di Chimica dell'Ambiente e dei Beni Culturali, Cremona, 10 - 13 settembre 2025
ATTI DEL CONGRESSO
https://www.congressodabc.it/wp-content/uploads/2025/09/SCI_ABC_2025_CREMONA_BOOK_OF_ABSTRACT.pdf
CO₂ sequestration by gas hydrates in marine environment: investigation of seawater and sediment chemistry
by Marco Zannotti, Lorenzo Remia and Rita Giovannetti
Oral Communication at TUMA 2025 Congress, Firenze 20-21 Novembre 2025
BOOK OF ABSTRACTS
Book of abstract_TUMA2025.pdfPage updated
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