In situ methane recovery and carbon dioxide sequestration in methane hydrates: a molecular dynamics simulation study.

One intriguing idea for the simultaneous recovery of energy and sequestration of global warming gas is proposed by the transformation of methane hydrates to carbon dioxide hydrates with the injection of liquid CO(2). Here we use molecular dynamics simulations to show that the replacement can take place without melting of the network of hydrogen-bonded water molecules. Depending on the distance to the interface between the liquid CO(2) and solid clathrate hydrate, we find that the replacement occurs either via direct swapping of methane and CO(2) or via a transient co-occupation of both methane and CO(2) in one cavity. Our results suggest that, with a careful design of the operation condition, it is possible to replace methane from methane hydrates with CO(2) in the solid phase without much change in the geological stability.