Gas hydrates have received considerable attention due to their important role in flow assurance for the oil and gas industry, their extensive natural occurrence on Earth and extraterrestrial planets, and their significant applications in sustainable technologies including but not limited to gas and energy storage, gas separation, and water desalination Given not only their inherent structural flexibility depending on the type of guest gas molecules and formation conditions, but also the synthetic effects of a wide range of chemical additives on their properties, these variabilities could be exploited to optimise the role of gas hydrates This includes increasing their industrial applications, understanding and utilising their role in Nature, identifying potential methods for safely extracting natural gases stored in naturally occurring hydrates within the Earth, and for developing green technologies This review summarizes the different properties of gas hydrates as well as their formation and dissociation kinetics and then reviews the fast-growing literature reporting their role and applications in the aforementioned fields, mainly concentrating on advances during the last decade Challenges, limitations, and future perspectives of each field are briefly discussed The overall objective of this review is to provide readers with an extensive overview of gas hydrates that we hope will stimulate further work on this riveting field

Gas hydrates in sustainable chemistry

Insights into the formation mechanism of hydrate plugging in pipelines

Performance evaluation of methane separation from coal mine gas by gas hydrate formation in a stirred reactor and in a fixed bed of silica sand

Insights into methane hydrate formation, agglomeration, and dissociation in water + diesel oil dispersed system

The energy demand for space cooling has more than tripled for the past thirty years and was responsible for emissions of about 1 Gt CO2 annually. The ever-increasing energy demand for cooling has posed a demanding question on improving the energy efficiency of cooling processes. On the other hand, with the growing global demand on LNG, cold energy released from LNG terminals has been growing to a historical high at 6.6 × 1014 kJ in 2017. Thus, there is a strong need to search for a suitable phase change material (PCM) best utilizing the cold energy released from the production sectors for storage and transport to the needed sectors. Among all the PCMs, semiclathrate hydrates (SCHs) with a suitable phase change temperature (5–27 °C) and high latent heat (190–220 kJ/kg) stand out as one promising candidate (a) to store and transport the cold energy and (b) to improve the energy efficiency of the cooling processes synergistically. In this review, we focus on reviewing SCHs as a cold energy storage and transport PCM covering both its fundamental properties (thermophysical properties, kinetics of formation and dissociation, rheological and transport properties, and safety and economic aspects) and its novel applications in several cooling processes. Prospects and challenges are also delineated on commercializing SCHs as a key technology enabler for the cold energy industry. There is strong confidence that possible disruptive SCH-based cooling technologies could be developed in the near future for energy efficiency improvement and environmental sustainability.

Shu-Shan Niu

Papers

Flow characteristics and rheological properties of natural gas hydrate slurry in the presence of anti-agglomerant in a flow loop apparatus

Experimental and modeling studies on the viscosity of (diesel oil + water + anti-agglomerant) system at high pressures