Cosmos
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By Cosmos
By Claire Jordan-Peters
An Australian energy company is teaming up with the CSIRO to work out if hydrogen can be safely stored underground in depleted gas fields in Victoria.
Lochard Energy’s H2RESTORE project is investigating the opportunity to use its existing gas fields for underground hydrogen storage, which is described as: “to shift low carbon energy seasonally.”
In March the Australian Renewable Energy Agency (ARENA) awarded $2m from its Advancing Renewables Program towards Lochard Energy’s 18-month $6.3 million study. In Europe two experimental sites are also testing underground hydrogen storage in depleted gas fields.
The CSIRO is assisting with the technical analysis of how hydrogen will behave in subsurface sandstone formations, 1400 to 1800m below the surface.
Dr Jonathan Ennis-King, Reservoir Simulation and Underground Storage Characterisation Team Leader at the CSIRO, says a major question is how stored hydrogen might interact with the rocks, fluids and microbes in the existing gas field, and the cement used for well construction.
“We will conduct laboratory studies, exposing rock samples from the relevant sites to hydrogen at subsurface temperature and pressure, over a period of weeks to months,” says Dr Ennis-King.
“We will perform similar tests on samples of wellbore cement, to see if there are any changes due to hydrogen exposure. Matching lab results with theoretical modelling will enable us to make predictions at the field scale.”
Hydrogen can be stored in tanks as a gas under pressure or as a liquid at very cold temperatures. However, for large-scale storage of hydrogen, Ennis-King says the cheapest and safest options are found underground. These include salt caverns, depleted gas fields, saline aquifers, or engineered hard-rock caverns.
Salt cavern storage is the most-ready technology. However, depleted gas field storage is widely available in Australia and will require less upfront investment. Depleted gas fields are geological formations previously used to extract natural gas. In depleted fields, hydrogen could be stored in the pores of naturally occurring sandstone formations, beneath formations that prevent the movement of gases.
Hydrogen and the regions
If Lochard Energy’s investigations are successful, it is looking to build a pilot hydrogen production and storage plant. The plant could use abundant renewable energy from the grid to produce hydrogen and store it until it’s needed weeks or months later to provide energy back into the grid.
Dr Joel Sarout, Geomechanics & Multi-physics Group Leader at CSIRO, wrote in March 2024 that cost-effective, large-scale hydrogen storage “will be a game-changer to the emerging hydrogen industry, supporting a range of domestic and export applications across sectors.
“To lower initial capital costs/investments, and potentially reduce operating costs, two geological storage and management options are effectively considered in Australia – blending up to 10-15% hydrogen in existing seasonal subsurface natural gas reservoirs and high purity hydrogen storage in aquifers and depleted gas (or possibly oil) reservoirs.
“Hydrogen mobility through porous reservoir rocks and the impact of geochemical interactions with the rock frame in presence of formation brine are currently poorly understood, with extremely limited hard data available in the literature.
“Hydrogen is expected to progressively diffuse into water (2 to 5% in the long-term), while strongly reacting with iron-bearing minerals (clays, iron oxides/sulphides) and organic matter.
“To what extent such reactions will affect pore structure and mineral composition remains to be assessed, and the impact on rock properties (transport, storage, mechanical, seismic) needs evaluating at pressure conditions relevant for the target reservoir depths.”
Sarout has been leading the development of CSIRO’s rock-hydrogen laboratory capabilities in Perth allowing for this type of critical feasibility assessment for multiple geological settings, spanning from underground caverns in rock salt formations, to depleted hydrocarbon reservoirs.
Claire Jordan-Peters is a journalist at the CSIRO media team. This content was published in two articles (here and here) at CSIRO News.
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