DOE Funds Keyes to Develop Novel Gas Hydrate Simulation Methods
Gas hydrates – ice with small molecules trapped in cages – are important for the energy sector because they store natural gas and carbon dioxide, block gas pipelines with an enormous cost impact, and hold potential for hydrogen storage and water purification. In a 3-year, $500K award, the Department of Energy has funded Prof. Tom Keyes to uncover the mechanism, or pathway, of gas hydrate formation. The pathway is a complex sequence of steps involving solvation, association, nucleation, growth, and a first-order-like transition, with a free energy barrier and unstable regime of thermodynamic states. Consequently, the theory of hydrate formation is in an early stage, and computer simulations using conventional algorithms have been hampered by the rarity of rate-limiting visits to the barrier.
The project, “Combining novel simulation methods and nucleation theory to uncover the secrets of gas hydrates,” brings together investigators with expertise in enhanced simulation methods and nucleation theory. The recently developed generalized replica exchange method (gREM) will be used to perform hydrate simulations in which “rare events” pose no difficulty, the transition regime is robustly sampled and characterized, the critical configurations are identified, and the effect upon them of suppressants such as salts and methanol is determined. The PI’s POLIR potential, the first capable of describing aqueous vibrational spectroscopy with classical mechanics, will be used to obtain the Raman and IR spectra of hydrates.
In conjunction with the simulations, collaborators (Prof. Bill Klein, Department of Physics, BU, and Prof. Harvey Gould, Department of Physics, Clark University) will develop the nucleation theory of hydrates, emphasizing the techniques which they have developed in their long association.