Abstract: An encagement vessel contains water and a working gas capable of forming hydrate with the water. A heat exchange arrangement is associated with the encagement vessel for removing heat from the working gas and water in the encagement vessel to form gas hydrate at an initial temperature. A working gas supply continues to add working gas to the encagement vessel as heat is removed in order to maintain the equilibrium pressure of the gas hydrate at the equilibrium pressure associated with the initial temperature as the hydrate is formed. An equilibrium pressure shifting arrangement increases the equilibrium pressure of the gas hydrate to an end pressure. A dissociating heat exchanger is included for adding heat to the hydrate at the end equilibrium pressure to dissociate the gas hydrate into water and working gas at the end pressure.