Enhanced methane storage capacity in clathrate hydrate induced by novel biosurfactants: Kinetics, stability, in vivo, and biodegradation investigations

Fast kinetics of gas hydrate growth, high storage capacity, high stability of hydrates formed, and no foam formation in the gas recovery stage are key factors in commercializing methane storage technology based on gas hydrates. The effects of gas hydrate promoters on the environment and living cells should also be considered. To address these critical considerations, castor oil was used in this study to synthesize four novel biosurfactants (BSCOs) using a green method to accelerate the rate of methane hydrate formation and increase its storage capacity. The results showed that the water-to-hydrate conversion in the presence of BSCO3 was 97 %, corresponding to a storage capacity of 186.3 v/v in only 9.5 min without foam formation. Additionally, a maximum conversion of 89.1 % and a storage capacity of 171 v/v were achieved in 3.5 wt% NaCl solution, indicating the potential of BSCOs to enhance methane hydrate formation in saline water. BSCOs proved to be compatible with the environment and the living cells as 20.8 % of the biosurfactant degraded over 28 days without toxicity to the internal organs of mice. Furthermore, only 7.5-10.5 % of the methane hydrates stored at 1 atm and -5 degrees C were dissociated during 14 days, indicating the hydrates formed in the presence of BSCOs are highly stable. To the best of our knowledge, this is the first report of the fastest water-to-hydrate conversion, and the highest storage capacity of methane hydrates using bio-based kinetic gas hydrate promoters. This study presents a solution to foam formation, hydrate stability, and environmental challenges of hydrate-based methane storage technology.