• Sander, Regina
• Ennis-King, Jonathan

Abstract

Widespread adoption of hydrogen in Australia as an energy carrier will require storage options to buffer the fluctuations in supply and demand, both for domestic use and for export. Once the scale of storage at a site exceeds tens of tonnes, underground hydrogen storage (UHS) is the preferred option for reasons of both cost and safety.The literature on UHS was reviewed, highlighting the main options for UHS under consideration, and the technical challenges that surround each one. The reservoir engineering aspects of UHS in porous media were also explored, providing some of the tools for assessing storage capacity, losses, and containment. The literature of UHS economics was also surveyed, indicating the variance in costs estimates and the need for an integrated assessment of total costs of hydrogen production, transport, and storage.The energy landscape in Australia was summarised, and the scale of potential future demand for UHS was estimated by considering plausible scenarios in three areas of application for energy storage. For stabilisation of the electricity network, this corresponds to around 10,000 tonnes of hydrogen. For security of the gas network (fully converted to hydrogen), the amount is about 2.5 million tonnes. For potential export, the storage requirements are similarly around 2.5 million tonnes.A methodology was developed for assessing the suitability of UHS options in Australia, and for making storage capacity estimates (only for depleted gas fields).This methodology was then applied to the whole of Australia. The key aim was to estimate the scale of prospective storage in each region, and classify options by their suitability, rather than to rank potential storage sites. The focus at this stage was on a technical assessment of geological factors and the assessment does not take social, environmental or economics issues into consideration.UHS in salt caverns (created by circulation of water) is an established technology internationally, with individual sites able to store a few thousand tonnes of hydrogen. Various Australian sedimentary basins contain salt deposits potentially suitable for the creation of storage caverns; however, most of these salts are in areas that are not near potential hydrogen generation, ports, or processing infrastructure. The most likely locations are in the north-western part of the Canning Basin, which is relatively close to the North West Shelf gas processing facilities and in the vicinity of new renewable wind and solar energy projects. The salt deposits in the Adavale Basin in western Queensland, and the Amadeus Basin in the Northern Territory, may also be suitably located for some projects.Further exploration for salt deposits may open up additional locations where salt cavern storage for UHS is viable.Depleted gas fields have also been used previously for storage of hydrogen-rich gas mixtures as well as natural gas storage and appear to be the most promising and widely available UHS option in Australia. There are still technical challenges to be addressed, such as the extent of possible contamination of the stored hydrogen with residual hydrocarbons, and the possible effects of geochemical reactions and microbial processes. The total prospective UHS capacity in such sites has been estimated using reserves and production data to be 310 million tonnes. Most Australian sedimentary basins contain multiple gas fields with an individual prospective storage capacity of more than 200,000 t H2.A much more detailed site-by-site assessment would be required to estimate how much of this prospective storage capacity could be commercial, considering various operating parameters and costs, as well as social and environmental factors.UHS in saline aquifers is also possible, building upon widespread international experience with underground gas storage in such locations. Many Australian basins contain multiple reservoir-seal pairs that should be suitable for UHS. The further requirement is then to locate suitable structures which could contain the stored hydrogen. That will require additional exploration and characterisation in these basins, and so a quantitative estimation of UHS capacity was not possible within the scope of this project. Although UHS in saline aquifers has not yet been demonstrated in industrial applications, it represents an option with a larger regional extent than storage in depleted gas reservoirs and may be considered if contamination issues from residual hydrocarbons are found to be significant.UHS in engineered hard-rock caverns, whether purpose-built or re-purposed from mining infrastructure, is a concept that builds on international experience with compressed air storage. It has a much lower technology readiness level (TRL) than the options discussed above, and there are major technical challenges around both containment and geomechanical stability. The main area of application would be in regions with significant po...

Topics

• porous
• impedance spectroscopy
• Hydrogen