Gas hydrate technological applications: From energy recovery to carbon capture and storage

Hydrates are crystalline structures that trap small gas molecules inside hydrogen-bonded water cages. These structures form at high pressure and low temperature. In recent years, there has been a growing interest in gas hydrates for technological applications, specifically in energy recovery, as well as carbon dioxide capture and storage. In the CO2/CH4 exchange using gas hydrates, researchers have reported a large amount of natural gas trapped in the form of gas hydrates under the ocean seafloor and permafrost regions. This large amount of natural gas trapped inside hydrate cages in oceanic and permafrost deposits has driven interest in the energy sector to investigate the possibility of safely harvesting gas hydrates as one of energy resources. However, there are still unanswered fundamental questions including the mechanism of natural gas recovery from gas hydrates. Another gas hydrate-based technology that has a growing interest is the use of gas hydrates for separation including carbon dioxide capture and storage. Carbon dioxide molecules have been shown to be preferentially trapped in the hydrate phase, demonstrating the possibility of the usage for carbon capture technology. Similarly, there are still underlying concerns of these applications, such as thermodynamics and stability of gas hydrates in porous materials, and the crystallization kinetics and mechanism of hydrate formation. This paper provides an overview of laboratory investigations conducted to understand the mechanism and evaluate the feasibility of energy recovery as well as discussion on recent advances in laboratory investigations on gas hydrate-based technology.