Geological CO₂ Capture and Storage with Flue Gas Hydrate Formation in Frozen and Unfrozen Sediments: Method Development, Real Time-Scale Kinetic Characteristics, Efficiency, and Clathrate Structural Transition

Abstract

The climate system is changing globally, and there is substantial evidence that subsea permafrost and gas hydrate reservoirs are melting in high-latitude regions of the Earth, resulting in large volumes of CO2 (from organic carbon deposits) and CH4 (from gas hydrate reserves) venting into the atmosphere. Here, we propose the formation of flue gas hydrates in permafrost regions and marine sediments for both the geological storage of CO2 and the secondary sealing of CH4/CO2 release in one simple process, which could greatly reduce the cost of CO2 capture and storage (CCS). The kinetics of flue gas hydrate formation inside frozen and unfrozen sediments was investigated under realistic conditions using a highly accurate method and a well-characterized system. The results are detailed over a wide range of temperatures and different pressures at in situ time scales. It has been found that more than 92 mol % of the CO2 present in the injected flue gas could be captured under certain conditions. The effect of different relevant parameters on the kinetics of hydrate formation has been discussed, and compelling evidence for crystal-structure changes at high pressures has been observed. It has also been found that temperature rise leads to the release of N2 first, with the retention of CO2 in hydrates, which provides a secondary safety factor for stored CO2 in the event of a sudden temperature increase.

One-Dimensional Study on Hydrate Formation from Migrating Dissolved Gas in Sandy Sediments

“…When circulation stopped, hydrate growth stopped, and hydrate saturation basically remained unchanged due to an insufficient gas supply. In free gas mode, the interaction between gas and water in the sediment was limited by the formed hydrates, resulting in low hydrate formation [31,32]. In this study, hydrate growth was limited by the difficult availability of dissolved gas rather than the transfer of methane between water and hydrate phases.…”

An Experimental Investigation on the Kinetics of Integrated Methane Recovery and CO2 Sequestration by Injection of Flue Gas into Permafrost Methane Hydrate Reservoirs

“…Well-characterized sands from Fife, Scotland were used for simulating mesoporous hydrate reservoirs. As described in our previous work 31 , the Sand mainly consists of quartz which has very small gas adsorption capacity 33 compared to gas inclusion in clathrate hydrate and water. Accordingly, the effect of gas adsorption to the sand was neglected in this study.…”

“…This is a positive sign as it shows N 2 not only acts as promoting agent for CO 2 /CH 4 replacement but also provides another safety factor for retention of the CO 2 -rich hydrates during temperature rise. We have previously showed 31 the role of N 2 for providing safety factor for thermal stability of stored CO 2 by hydrate formation using flue gas in absence of initial methane hydrate in place. However, this is the first mention of the potential safety role of N 2 for methane recovery by flue gas injection.…”

Heat Transfer in Unfrozen and Frozen Porous Media: Experimental Measurement and Pore‐Scale Modeling

“…Research‐grade N 2 (purity 99.995 vol.%) was supplied by BOC Ltd. Deionized water generated by an integral water purification system (ELGA DV 25) was used throughout the experiments. The simulated sediment used in this study was a well‐characterized silica sand from Fife, Scotland (grain density: 2.64 g/cm 3 , mean size: 257 μm, and specific area: 0.059 m 2 /cm 3 ); a detailed analysis of which could be found elsewhere (Hassanpouryouzband, Yang, Okwananke, et al, 2019; Hassanpouryouzband, Yang, Tohidi, et al, 2019).…”