Rock shaft would store hydrogen for multiple uses.
Plans have been unveiled for the construction of hundreds of purpose-built underground hydrogen stores.
Edinburgh-based underground energy storage firm Gravitricity has signed a memorandum of understanding with infrastructure company VSL Systems UK – part of the French Bouygues Construction group – to complete the design of steel-lined underground rock shafts.
The two companies are now seeking funds for the project, which would see them build a scale demonstrator in the next two years ahead.
Under the plans, each rock shaft would be six metres in diameter and 365 metres deep.
Gravitricity said a single store could hold up to 100 tonnes of green hydrogen and added that building 1000 such stores could meet a quarter of the UK government’s predicted 2050 hydrogen storage needs.
“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 Gravitricity managing director Charlie Blair.
“Purpose-built lined rock shafts will be the safest and most affordable way to store large volumes of hydrogen near to where it will be required.
“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.”
The current front-runners for storage are underground salt caverns and above ground storage, but Blair said “salt caverns offer scale, but very little flexibility – they only exist in certain locations, while above-ground systems lack scale”.
“We believe we have a Goldilocks solution which can be delivered safely and affordably to meet the growing hydrogen economy’s needs.”
He added that the stores can be constructed wherever they are required and are not dependent upon specific geological locations, meaning single or several stores could be built near renewable-powered green hydrogen production facilities.
Blair believes a single rock shaft could “store the green hydrogen generated by a 460 MW offshore wind farm and could be emptied and refilled daily, whilst multiple stores could soak up vast amounts of otherwise wasted or ‘constrained’ wind”.
Gravitricity has identified several sites for the UK pilot project and is in discussion with those site owners.
The company recently completed a £300,000 feasibility study in conjunction with consultancy ARUP and funded by the UK 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.
“If green hydrogen is to become a mass market fuel of the future then we need to find ways to store it safely and in large quantities close to where it is needed,” Blair said.