Perturbing the stability of gas hydrates

Gas hydrates can be found in large amounts in the permafrost region at the bottom of the sea floor in porous rocks or in sand, in the proximity of water. They represent a potential resource for the energy. The gas trapped into the hydrate can be considered as an alternative to the conventional fuel resources. Furthermore, the nature of gas hydrates allows one to consider them as potential storage facility for unwanted greenhouse gases. Therefore, addressing the stability of hydrates with desired gas, stored in it, is reasonable and realistic.

We conduct molecular simulations (Molecular Dynamics, Monte Carlo) using classical force fields to investigate the thermodynamic stability of various gas hydrate structures that contain methane, CO2 and some of the additives mentioned above. In particular, we develop a framework which will enable us to predict the phase diagram (dissociation temperature and pressure) as a function of the loading and (partial) pressure of all guest molecules (including additives), for various host structures of the hydrate. This requires the calculation of the Gibbs or Helmholtz energy of the hydrate as well as saturated liquid water solutions of the guest molecules.