In the context of energy revolution large quantities of storage capacity are required for the integration of strongly fluctuating energy production from wind and solar power plants. The conversion of electrical energy into chemical energy in the form of hydrogen is one of the technical possibilities. This technology, where hydrogen is stored in subsurface formations similar to the storage of natural gas, is currently in the exploratory focus of several European countries. Despite the deviating hydrodynamic behavior of hydrogen compared to natural gas, bio-chemical reactions can have an imported role in underground hydrogen storage. The fact that hydrogen is a favored substrate for several anaerobic microorganisms induces their growth and results in a degradation of hydrogen. In particular the activity methanogenic archaea can lead to drastic variations in the gas composition which were observed in some former town gas storages. To describe this behavior a mathematical and numerical model was developed in preliminary work which couples compositional two-phase flow with bio-chemical reactions and the dynamics of microbial growth and decay. In the present paper the stability of the coupled dynamic system was analyzed. Dependent on the parameter space it was shown that the system can undergo a limit cycle behavior or diffusion-driven (Turing) instability. The numerical solutions within these parameter regions show different oscillatory regimes. The instability leads to the formation of alternating spots with either a high concentration of H2 or a high concentration of CH4. The injection rate is a decisive factor which controls the behavior of the dynamic system.


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