Gas storage via clathrate hydrates: Advances, challenges, and prospects

Hydrate-based gas storage technology is a novel and promising method for gas storage and transport, with key features like compact storage, benign process, easy gas recovery, non-explosive, mild storage conditions and robustness against impurities. The slow formation kinetics, high compression and refrigeration cost, and longterm storage stability were the major challenges and concerns. This review provides a comprehensive overview of the development of hydrate-based method for gas storage, mainly focusing on the hydrate formation and storage steps. Strategies to shift hydrate equilibrium toward milder conditions, enhance hydrate formation kinetics and improve hydrate storage stability are discussed. Highlights of recent trends include the employment of greener, safer and more efficient promoters like amino acids, the ultra-rapid formation and breakthrough gas uptake achieved by synergistic effect of thermodynamic and kinetic promoters, and the shift of self-preservation effect to temperatures above 273.2 K. Some challenges still exist, such as the relatively high volatility of the organic promoters, the additional material cost associated with the use of promoters and the uncertainty of selfpreservation effect for long-term and large-scale storage. Some prospective research directions of the hydratebased gas storage technology could be to develop greener and more effective promoters, evaluate the value chain based on sII hydrates, and explore its potentials in some specific applications such as long-term stationary gas storage.