The concept of hydrogen-methane blends storage in underground mine excavations - Gas permeability of concrete

Power-to-gas technology gives the possibility to store the excess power from renewable energy sources by converting electrical energy into gas such as eg. hydrogen. There is however a problem with accessibility of sites where pure hydrogen can be stored. Hence, the idea of blending hydrogen with methane and use underground mine excavations to increase the storage capacity, apart from salt caverns. However, hydrogen has strong capability to diffuse through different materials, including steel and some minerals. The paper proposes a concept of hydrogen/methane blends storage in abandoned underground mine excavations. Research is focused on permeability of concrete as a barrier for stored gases. Gas permeability from two methods: pulse - decay and steady - state, were compared. Gas permeability of investigated concrete and geopolymers depends on the composition and pressure conditions, including axial stress. A significant improvement of tightness of the concrete can be achieved, using a synthetic compounds.