Energy plan

Gravitricity seeks £40m to build hydrogen stores

Charlie Blair at Newtongrange Mining Museum, Scotland
Charlie Blair: affordable storage process

Scottish energy storage start-up Gravitricity is seeking up to £40 million to roll-out its plans to store hydrogen underground.

The Edinburgh-based company believes hundreds of zero emission stores could be built in the UK. Hydrogen can be extracted from the storage sites as required to fuel industrial vehicles or to be burnt in power plants when the wind eases.

Gravitricity was founded in 2011 and its system uses surplus electricity to winch a weight up a disused mine shaft or other underground cavity, then using gravity to drop it back and releasing the stored energy to generate power.

It believes its storage technology – known as FlexiStore – offers a system that is larger and more secure than above ground hydrogen storage, and more flexible than subterranean salt caverns, the two most commonly-proposed alternatives.

Each rock shaft would be six metres wide and 365 metres deep and lined with steel. A single store would hold up to 100 tonnes of green hydrogen – sufficient to refuel more than 1,000 HGVS, or to power 500 buses for a week.

Gravitricity calculates that construction of just 1,000 FlexiStores would meet a quarter of the UK Government’s predicted 2050 hydrogen storage needs.

The company recently completed a £300,000 feasibility study, conducted with 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.

It has signed a memorandum of understanding with VSL Systems UK, an infrastructure specialist that is part of Bouygues Construction, of France, to complete detailed design work for the prototype, which it aims to build within the next two years.

The company is also in advanced discussions with Cumbrian steel specialists Bendalls Engineering to fabricate the linings for the rock shafts. 

Charlie Blair, Gravitricity’s managing director, said: “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.  

“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.”

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