Feasibility of hydrogen storage in depleted hydrocarbon chalk reservoirs: Assessment of biochemical and chemical effects

Hydrogen storage is one of the energy methods that can help realization an emission free future by saving surplus renewable for deficit periods. Utilization depleted hydrocarbon reservoirs large-scale hydrogen may be associated with risk chemical/biochemical reactions. In specific case chalk reservoirs, principal reactions are abiotic calcite dissolution, acetogenesis, methanogenesis and biological souring. Here, we use PHREEQC to evaluate dynamics extent loss each these in scenarios various Danish North Sea reservoirs. We find that: (i) Abiotic dissolution does not occur temperature range 40-180° C. (ii) If methanogens acetogens grow as slow slowest growing reported literature, acetogenesis cannot cause a more than 0.6% per year. However, (iii) if they proceed fast fastest complete all injected less five years possible. (iv) Co-injection CO2 employed inhibit keep produced methane due carbon neutral. (v) Biological sulfate reduction significant during 10 years, but it lead high sulfide concentrations (1015 ppm). expected impact only early stages source sulfur substrates dissolved species brine rock minerals. Considering findings, suggest possess risks good candidates underground storage.