Energy storage company Gravitricity has signed a memorandum of understanding with VSL Systems UK to explore the use of deep underground green hydrogen storage.
Gravitricity’s solution, called FlexiStore, involves raising weights in disused mine shafts and releasing them when energy is needed. The system could also be used to store green hydrogen, which is produced through renewable energy sources.
Gravitricity has stated that its solution is more flexible than subterranean salt caverns, as it does not require specific geographical locations.
Each FlexiStore would be six metres in diameter, 365 metres deep, and capable of holding up to 100 tonnes of green hydrogen. The partnership aims to reduce the cost of green hydrogen by reducing transportation costs and help the UK reach its net zero goals by 2050.
“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,” said Charlie Blair, managing director of Gravitricity.
“At present, the main proposals for storage are underground salt caverns and above ground storage. Salt caverns offer scale, but very little flexibility – they only exist in certain locations; whilst 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.
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This agreement follows Gravitricity running a successful a 250kW demonstrator in Edinburgh in 2021, proving the novel technology’s capability. Following this, it secured project support led by the European Investment Bank for its plans to build a full scale 4-8MW project in a former mine shaft in 2022.
