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Hydrogen can act as an energy store to balance supply and demand in the renewable energy sector. Hydrogen storage in subsurface porous media could deliver high storage capacities but the volume of recoverable hydrogen is unknown. We imaged the displacement and capillary trapping of hydrogen by brine in a Clashach sandstone cylinder at 2-7 MPa pore fluid pressure using X-ray computed microtomography. Hydrogen saturation obtained during drainage at capillary numbers of

Hydrogen energy will remarkably aid the global energy transition from fossil fuels to renewables. Hydrogen is the lightest molecule. It requires large volume storage facilities only found in geological formations. Salt caverns are a potential geo-storage medium that has been used in practice at a commercial scale. In Australia, several basins, i.e., Advalae, Carnarvon, Amadeus, Officer, and Canning, have been identified with notable salt deposits. The feasibility and potential of storing hydrogen in these salts have yet to be determined by geology, salt thickness, or salt type data. Here, we identified potential hydrogen storage sites. Additionally, hydrogen storage volume was estimated in Mallowa and Minjoo salts (Carribuddy salts: ~95 % halite and ~1 % anhydrite) in Willara Sub-basin, Canning Basin, Western Australia (WA). The results show a high potential for constructing salt caverns for hydrogen storage in these areas. The geochemical data suggest the presence of Bromine (90 to 670 ppm and

Climate change, triggered by a continuously rising use of carbon based energy sources, is a global concern. Geological hydrogen storage, e.g. in depleted gas fields or saline aquifers, can overcome imbalances between supply and demand in the renewable energy sector and facilitate the transition to a low carbon emissions society, in this way mitigating climate change. However, a range of subsurface microorganisms utilise hydrogen which may have important implications for hydrogen recovery, clogging and corrosion. We created a novel, globally applicable risk categorization tool based on the published environmental growth constraints of all major hydrogen utilizing microbes (hydrogenotrophic methanogens, hydrogenotrophic sulphate reducing bacteria, homoacetogens and hydrogenotrophic dissimilative iron reducing bacteria) and on reports of paleosterile subsurface environments. Application of the tool to 75 depleted or close to depleted gas fields on the UK continental shelf showed that 9 fields fall either within the ´No Risk´ category with temperatures >122 °C, making them the ideal candidates for hydrogen storage from a microbial risk point of view. Hydrogen storage in the 35 ´Low Risk´ fields with temperatures >90 °C or the 22 ´Medium Risk´ fields with temperatures >55 °C and salinities >1.7 M NaCl will require the careful characterization of the microbial community composition to assure that hydrogenotrophic microorganisms are not present. We recommend against utilising depleted gas fields with temperatures

Geological H2 storage plays a central role to enable the successful transition to the renewable H2 economy and achieve net-zero emission in the atmosphere. Depleted oil and gas reservoirs are already explored with extensive reservoir and operational data. However, residual hydrocarbons can mix with injected H2 in the reservoirs. Furthermore, low density and high diffusivity of H2 may establish H2 leakage from the reservoirs via fault pathways. Interestingly, H2 can be consumed by microorganisms, which results in pore-network precipitation, plugging, and partial permeability impairment. Therefore, stored H2 may be lost in the formations if the storage scenario is not planned cautiously. While salt caverns are safe and commercially proven geo-rock for H2 storage, they have low-storage capacity compared to depleted gas reservoirs. Moreover, salt structures (e.g., domel, bedded) and microorganisms activities in the salt cavern are limiting factors, which can influence the storage process. Accordingly, we discuss challenges and future perspectives of hydrogen storage in different geological settings. We also highlight geographical limitations with diverse microbial communities and theoretical understanding of abiotic transformation (in terms of rock’s minerals, i.e., mica and calcite) for geological H2 storage. Regarding the fundamental behavior of H2 in the geological settings, it is less soluble in formation water; therefore, it may achieve less solubility trapping compared to CO2 and CH4. Furthermore, H2 gas could attain higher capillary entrance pressures in porous media over CH4 and CO2 due to higher interfacial tension. Additionally, the low viscosity of H2 may facilitate its injection and production but H2 may establish the secondary trapping and viscous fingering. Thus, this review documents a blend of key information for the amendment of subsurface H2 storage at the industrial scale.

Storage of energy-related products in the geological subsurface provides reserve capacity, resilience, and security to the energy supply chain. Sequestration of energy-related products ensures long-term isolation from the environment and, for CO 2 , a reduction in atmospheric emissions. Both porous-rock media and engineered caverns can provide the large storage volumes needed for energy security and supply-chain resilience today and in the future. Methods for site characterization and modelling, monitoring, and inventory verification have been developed and deployed to identify and mitigate geological threats and hazards such as induced seismicity and loss of containment. Broader considerations such as life-cycle analysis, environment, social and governance (ESG) impact and effective engagement with stakeholders can reduce project uncertainty and cost while promoting sustainability during the ongoing energy transition toward net-zero or low-carbon economies.

Hydrogen stored on a large scale in porous rocks helps alleviate the main drawbacks of intermittent renewable energy generation and will play a significant role as a fuel substitute to limit global warming. This study discusses the injection, storage and production of hydrogen in an open saline aquifer anticline using industry standard reservoir engineering software, and investigates the role of cushion gas, one of the main cost uncertainties of hydrogen storage in porous media. The results show that one well can inject and reproduce enough hydrogen in a saline aquifer anticline to cover 25% of the annual hydrogen energy required to decarbonise the domestic heating of East Anglia (UK). Cushion gas plays an important role and its injection in saline aquifers is dominated by brine displacement and accompanied by high pressures. The required ratio of cushion gas to working gas depends strongly on geological parameters including reservoir depth, the shape of the trap, and reservoir permeability, which are investigated in this study. Generally, deeper reservoirs with high permeability are favoured. The study shows that the volume of cushion gas directly determines the working gas injection and production performance. It is concluded that a thorough investigation into the cushion gas requirement, taking into account cushion gas costs as well as the cost-benefit of cushion gas in place, should be an integral part of a hydrogen storage development plan in saline aquifers.

The geological storage of hydrogen is necessary to enable the successful transition to a hydrogen economy and achieve net-zero emissions targets. Comprehensive investigations must be undertaken for each storage site to ensure their long-term suitability and functionality. As such, the systematic infrastructure and potential risks of large-scale hydrogen storage must be established. Herein, we conducted over 250 batch reaction experiments with different types of reservoir sandstones under conditions representative of the subsurface, reflecting expected time scales for geological hydrogen storage, to investigate potential reactions involving hydrogen. Each hydrogen experiment was paired with a hydrogen-free control under otherwise identical conditions to ensure that any observed reactions were due to the presence of hydrogen. The results conclusively reveal that there is no risk of hydrogen loss or reservoir integrity degradation due to abiotic geochemical reactions in sandstone reservoirs.