Synergistic Enhancement in Gas Hydrate Stability with Hybrid Promoters: A Step Toward Sustainable Hydrate-Based Energy Storage

Natural gas still constitutes a substantial portion of global energy demand, necessitating the development of more sustainable, economical, and safe technologies for its storage and transportation. Hydrate-based energy storage (HBES), which stores CH₄ in gas hydrate form, has emerged as a promising solution. This study reveals that specific combinations of thermodynamic promoters exhibit ‘synergistic promotion,’ and introduces the concept of ‘hybrid promoters’ to describe these combinations. For instance, mixtures of two promoters, cyclooctane and cyclooctanone, demonstrate enhanced promotion performance compared to their individual components. While cyclooctane and cyclooctanone individually increase the dissociation temperature of CH₄ hydrate by 4.5 and 6.0 K, respectively, their equimolar mixture achieves a greater increase of 7.0 K. Additionally, this study identifies several other combinations acting as hybrid promoters, suggesting that many remain undiscovered. These findings represent a paradigm shift from conventional approaches that focus solely on single promoters, broadening the applicability of gas hydrates and advancing HBES technologies toward more sustainable energy systems.