Molecular hydrogen storage in binary H2-CH4 clathrate hydrates

Abstract

Clathrate hydrate has emerged as a promising candidate for hydrogen storage, but the major challenge is the high pressure required for its formation. The addition of natural gas can significantly reduce the formation pressure, but also can improve the energy density. In this work, we estimated the hydrogen storage capacity of the H2-CH4 binary hydrate by performing the first-principles calculations and simulations. The thermodynamical and mechanical stability of the hydrate was studied as a function of the cage occupancy of both 512 and 51264 cages. For the most stable structure, the molar ratio of H2 and H2O is 0.353:1. The H2-CH4 binary hydrate can maintain its structure during dynamics under the moderate temperature and pressure. The self-preservation effect was observed at ∼270 K, which can be used for the hydrogen storage and transport. These findings provide a better understanding of the mixed hydrate as a viable hydrogen storage technology, which could enable us to achieve a sustainable hydrogen economy.