An energy storage start-up is seeking to raise up to £40 million to advance its plans to store hydrogen in underground rock shafts.
Gravitricity is aiming to build a prototype within two years and claims that eventually it could build hundreds of its “FlexiStore” facilities around Britain to enable the storage of the clean-burning gas.
Hydrogen can be made with zero emissions through the electrolysis of water powered by surplus renewable electricity, such as when it is very windy and turbines are generating more power than the cable network can handle.
Hydrogen could be withdrawn from the storage sites when needed, whether to fuel industrial vehicles or to be burnt in power plants when the wind slackens.
Gravitricity, based in Edinburgh, was founded in 2011 and takes its name from its original focus on a different, gravity-based energy storage system. That would use surplus electricity to winch a weight up a disused mine shaft or other underground cavity, before using gravity to let it drop back down again slowly, releasing the stored energy to generate power.
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However, as interest in the role of hydrogen in decarbonisation has grown, the company has expanded into hydrogen storage. It plans to bore rock shafts 365m deep and 6m wide and to line them with steel to securely store the gas. Each shaft could hold 100 tonnes of hydrogen, enough to refuel 1,000 heavy goods vehicles, and could be filled using the typical daily output of a 460-megawatt offshore wind farm.
Gravitricity received £300,000 funding from the government to complete a feasibility study, which it said had shown its technique was “technically and commercially feasible”. Now 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.
Charlie Blair, Gravitricity’s managing director, said it was “going out to market to raise £20 million to £40 million” to fund research and development, the construction of the prototype and the first full-scale underground deployment of its gravity storage technology.
Blair, 42, said that in future there was “absolutely nothing stopping us” combining its two energy storage systems, raising and lowering weights through the compressed hydrogen.
To date Gravitricity has received about £4 million in grant funding and has raised about the same again in equity, including through crowdfunding.
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Blair said its planned hydrogen stores could hold bigger volumes than could feasibly be stored safely above ground. “Explosive risk is a real thing with hydrogen,” he said. “That’s one of the really big advantages of going underground: it is very difficult for oxygen to get in, so you can’t get an explosive mix.”
