The huge resources of energy in the form of natural gas hydrates are widely distributed worldwide in permafrost sediments as well as in offshore sediments. A novel technology for combined production of these resources and safe long terms storage of carbon dioxide is based on the injection of carbon dioxide injection into in situ methane hydrate filled sediments. This will lead to an exchange of the in situ methane hydrate over to carbon dioxide dominated hydrate and a simultaneous release of methane gas. Recent theoretical and experimental results indicate that the conversion from natural gas hydrate to carbon dioxide hydrate and mixed carbon dioxide / methane hydrate follows two primary mechanisms. Direct solid state transformation is possible
