Seawater-based sII hydrate formation promoted by 1,3-Dioxolane for energy storage

Solidified natural gas (SNG) via clathrate hydrates offers a promising solution to overcome the challenges faced by both liquified natural gas (LNG) and compressed natural gas (CNG), enabling the storage of natural gas in a secure, large-scale, and long-continued fashion. Herein we utilized seawater to synthesize sII methane hydrate to reduce the raw material cost and evade the issue of water scarcity. Comprehensive experiments were performed to investigate the effects of temperature, pressure, and amino acids on mixed CH4/DIOX hydrate formation in seawater. Elevating the temperature from 283.2 K to 293.2 K resulted in a decrease in both the hydrate formation rate and methane storage capacity. Conversely, increasing the initial pressure from 7.2 MPa to 11.2 MPa enhanced both parameters. Hydrate morphology was presented to understand the evolution of hydrate systems under different experimental conditions. In-situ Raman analysis identified the structure of synthesized hydrates and unveiled the unique occupancy of guest molecules (DIOX and CH4) within the hydrate cages. The findings of this study contribute to the advancement of economically viable SNG technology through the direct utilization of seawater.