The Edinburgh-based company plans to build a scale demonstrator in the next two years before a commercial rollout, starting with a pilot project for the construction of hundreds of FlexiStore underground hydrogen stores around the UK.

A single FlexiStore would hold up to 100 tonnes of hydrogen which is sufficient to refuel more than 1000 HGVS or power 500 buses. The construction of 1,000 FlexiStores could meet a quarter of the UK Government’s predicted 2050 hydrogen storage needs.

Each rock shaft would be six metres in diameter, 365 metres deep and lined with steel, with green hydrogen generated by a 460MW offshore wind farm.

Gravitricity claims FlexiStore offers a system that is larger and more secure than above ground hydrogen storage and more flexible than salt caverns.

Charlie Blair, Managing Director of Gravitricity, said, “Purpose-built lined rock shafts will be the safest and most affordable way to store large volumes of hydrogen near to where it is 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.”

FlexiStores are not dependent upon certain geological locations, meaning single or multiple storage stores can be built close to renewable powered production facilities and can fuel hydrogen hubs and filling stations.

One FlexiStore would hold green hydrogen generated by an offshore wind farm that could be emptied and refilled daily, while multiple could soak up vast amounts of wasted wind, which amounted to 3.6TWh in 2020.

Gravitricity has identified UK sites for the project and is in discussion with site owners and are also in advanced talks with steel specialists Bendalls Engineering to fabricate the linings for the rock shafts.

Last year, the UK Government specified the need for strategic planning function to guide the rollout of hydrogen transport and storage infrastructure and potential implementation options.

A report by Hydrogen UK said that unlocking infrastructure investment for 3.4TWh of large-scale hydrogen storage is urgently required, recommending that a long-term regulated business model for large scale storage should be designed by 2025.

Read more: UK Government open for consultation on hydrogen transport and storage business models

Read more: Hydrogen UK: Unlocking large-scale hydrogen storage investments urgently required

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