Application of Steady-State Flow and Carrier Gas Methods for Determining Gas Permeability of Salt Rock

Abstract

Decarbonization and switching into Renewable Energy Sources (RES) is causing constant increase of demand for large – scale energy storage capacities. It is necessary to mitigate fluctuations from green energy production, caused especially by unstable wind and solar plants, dependent on weather conditions. Salt caverns can serve as large – scale underground energy storage facilities for hydrogen or other compressed gases (methane, syngas, compressed air – CAES). That kind of storage caverns are in use in multiple locations worldwide for natural gas and CAES, and in a few – for hydrogen storage. Due to outstanding sealing properties of salt rock, this is so far the only well-known and utilized underground hydrogen storage technology. However, salt rock is subject to creep process, which may impact cavern stability, as well as gas permeability properties. This paper presents results of hydrogen permeability of salt rock sample from Polish salt mine, investigated with blend of 10% of hydrogen in methane, using hybrid Steady-State Flow/Carrier Gas setup. Gas permeability of salt was investigated before and after creep process, which decreased gas permeability coefficient of sample by four orders of magnitude for pure hydrogen (10-19 to 10-23 m2). Different methods in one hybrid setup were used for investigation of gas permeability. In addition, paper compares hydrogen permeability coefficients of salt rock and synthetic polymers.