“Self-Preservation” of CH₄ Hydrates for Gas Transport Technology: Pressure–Temperature Dependence and Ice Microstructures

“Self-preservation” is a kinetic anomaly that allows for storing a substantial amount of gas locked in gas hydrate far outside its thermodynamic stability field for a period of days, weeks, or even months under very mild pressure–temperature (p–T) conditions, by merely maintaining temperatures below the melting point of ice. Utilizing this phenomenon for low-cost storage and transportation of natural gas is not yet sufficiently developed to be competitive with already existing, well-established methods (e.g., liquefied natural gas (LNG), gas to liquid (GTL), compressed natural gas (CNG), or pipeline (PL)). Aside from the refinement of numerous engineering and safety aspects, a deeper understanding of the “self-preservation” phenomenon is needed in order to promote these technologies. We address some of these outstanding issues in a series of isothermal–isobaric pressure–volume–temperature (pVT) experiments exploring the kinetics of the dissociation of pure sI methane hydrate to ice and CH4 gas in a wide p...