Understanding the uniaxial-deformation behavior of stable and unstable CO2hydrates under squeezing and stretching conditions

As an efficient method for lowering carbon emissions, sealing carbon dioxide (CO2) on the seabed with CO2hydrates has gained extensive interest from researchers in recent decades. Unfortunately, the underwater environment is not always quiet and peaceful, and crustal movement may impair the storage environment, making it unsuitable for storing CO2. To better understand how CO2hydrates change when subjected to external forces at the molecular level, we used the molecular dynamics method to simulate the behavior of stable and unstable CO2hydrates under squeezing and stretching conditions, respectively. According to the results, a significant amount of CO2is released alongside the transformation of a huge number of solid water molecules into liquid during the squeezing process. In the stretching process, the CO2hydrate can be pulled apart rapidly, with only a small area of the hydrate cage being damaged and some CO2escaping, and only the water molecules near the fracture surface changing from solid to liquid state. The three-body order parameter (F3) and the four-body order parameter (F4), water molecules number in different phase, and the hydrate cage number, all demonstrate the process of water molecules transitioning from solid hydrate form to liquid state. It can be concluded that, to avoid massive CO2emissions, it is necessary to anticipate geological changes and choose suitable hydrate storage sites in advance. In addition, new advancements in CO2conversion technology is necessary for safeguarding our planet.