Storage Integrity during Underground Hydrogen Storage in Depleted Gas Reservoirs

Abstract

The transition of energy from fossil fuels to renewable energy particularly hydrogen is becoming the centre of decarbonization and roadmap to achieve net-zero carbon emission. To meet the requirement of large-scale hydrogen storage as a key part of hydrogen supply chain, underground hydrogen storage can be the ultimate solution to economically store hydrogen thus meet global energy demand. Compared to other types of subsurface storage sites such as salt caverns and aquifers which are limited to geographical locations, depleted gas reservoirs have been raising more interest because of the wider distribution and higher storage capacity. However, safely storing and cycling of hydrogen in depleted gas reservoirs requires caprock, reservoir and wellbore to remain high stability and integrity. Nevertheless, current research on storage integrity during underground hydrogen in depleted gas reservoirs is still scarce and non-systemic. We therefore reviewed the major challenges on storage integrity associated with geochemical reactions, microbial activities, faults and fractures and hydrogen cycling perspectives. The processes and impacts of abiotic and biotic mineral dissolution/precipitation, faults and fracture reactivation and propagation in caprock and host-rock, wellbore instability due to cement degradation and casing corrosion, stress change during hydrogen cycling, etc. on storage integrity were comprehensive reviewed and analysed. Furthermore, a technical screening tool with consideration of controlling variables, risks and consequences on storage integrity was developed to identify the potential risks associated with storage integrity. Lastly, knowledge gaps together with feasible methods and pathways have been identified to mitigate the risks and thus enables large-scale underground hydrogen storage.

Characterization of sediment and granite hosted deep underground research laboratories reveals diverse microbiome functions, limited temporal variation and substantial genomic conservation

“…Beyond basic scientific interest in organisms that live there, the microbiology of these regions is an important practical consideration if they are to be used to store nuclear waste and other materials (e.g., CO2 or H2). Microbes in proximity to underground repositories may impact the stability of the stored material via container corrosion (e.g., Pedersen 1999;Rajala et al, 2015;Stroes-Gascoyne et al, 2010;Stroes-Gascoyne and West, 1997), by consumption of stored resources (e.g., H2, Dopffel et al, 2023;Liu et al, 2023) or by degrading containment integrity (e.g., via increasing rock porosity and/or permeability, Zeng et al, 2023).…”

The Influence of Microbial Activities on the Capillary Pressure during H2 Injection: Implications for Underground H2 Storage

“…However, their storage volume is quite small, and they could be located far away from H 2 generation sites or local pipelines. 32,33 Some recent studies have examined the likely microbial and geochemical reaction risks that could be associated with UHS and carbon dioxide geostorage. Park et al 34 assessed the impacts of biosurfactants produced by Bacillus subtilis on CO 2 /brine/ rock interfacial interactions.…”

“…In salt caverns, the bacterial activities are inhibited by the saline environments, and H 2 permeability is lower than that of depleted hydrocarbon reservoirs, ensuring that microbial H 2 loss and contamination with surrounding fluids are curtailed. However, their storage volume is quite small, and they could be located far away from H 2 generation sites or local pipelines. , …”