UK company Gravitricity is looking to raise funds to build a network of underground hydrogen stores after teaming up with specialist construction company VSL Systems to build a pilot of the purpose-built underground lined rock shafts before the end of 2024.
Edinburgh-based Gravitricity, which specialises in developing underground energy storage, has signed a memorandum of understanding with VSL to complete the design of the underground hydrogen stores and has identified potential sites for the pilot project.
Talks were said to be underway with site owners, including utilities, regarding the pilot project and future commercial schemes.
The proposed FlexiStore storage technology is a “goldilocks" solution to the challenge of green hydrogen storage, managing director Charlie Blair said, as it would be “more flexible" than underground salt caverns, which have been proposed by UK Oil & Gas, and “larger and more secure" than above-ground storage.
Each rock shaft would be six metres in diameter and 365 metres deep and lined with steel, enabling a single store to hold up to 100 tonnes of green hydrogen, or enough to power 500 buses for a week.
This would allow the facility to store the green hydrogen generated by a 460MW wind farm and could be emptied and refilled daily.
The UK government has predicted that between 12TWh and 51TWh of hydrogen storage will be required in 2050 as part of its net zero planning.
Gravitricity, which is also developing gravity-based energy storage projects, said the stores can be constructed “wherever required and are not dependent upon specific geological locations" as is the case with salt caverns, such as close to hydrogen production facilities.
“Green hydrogen will be a vital fuel of the future in industrial applications and in heavy transport, where electrification is just not feasible, or where industrial grey hydrogen is already used,” said Blair.
“It is difficult to transport hydrogen. It therefore makes sense to locate hydrogen storage systems close to sources of renewable power – which can generate green hydrogen – and to potential users."
Gravitricity recently completed a £300,000 feasibility study as part of the government’s BEIS HySupply programme, which showed it is technically and commercially feasible to store large amounts of compressed hydrogen in an underground lined rock shaft.