Patented underground hydrogen storage technology selected by National Gas

National Gas has secured £500,000 from Ofgem’s Strategic Innovation Fund to develop an innovative new type of underground hydrogen storage – which could see a pilot project built in 2026.

The system, known as H2FlexiStore, has been developed by Edinburgh energy storage specialists Gravitricity, and is designed to hold up to 100 tonnes of green hydrogen in purpose-built underground lined shafts.

Gravitricity’s patented system uses purpose built lined geological shafts to store up to 100 tonnes of pressurised hydrogen at 200 bar per shaft, equivalent to 3.3GWh of raw energy (enough to drive 10,000,000 miles in a hydrogen fuel cell car).

H2FlexiStore developed by Gravitricity. Source: gravitricity.com

The funding follows the successful completion of a National Gas led feasibility study in 2024, which identified H2FlexiStore as the preferred technology to provide locationally flexible hydrogen storage.

The initial study concluded that underground nodal storage would compensate for the loss of ‘linepack’ (the amount of energy that can be stored in a pipe network) when transitioning to green hydrogen as a fuel

A successful demonstrator project would validate the benefits of underground storage to the hydrogen industry and key infrastructure.

Martin Wright, Gravitricity’s co-founder and executive chairman, said: “Given the strategic need for grid-scale energy storage, it is crucial that enabling hydrogen storage technologies such as H2FlexiStore are commercially mature in time to offer cost effective resilience within current and future energy systems.”

Kelvin Shillinglaw, innovation analyst at National Gas, commented: “This project is a critical step forward in ensuring the UK’s gas networks are ready for a hydrogen-powered future.

Martin Wright concluded: “By deploying H2FlexiStore, we anticipate network operators will be able to extend the life of existing assets as they transition to hydrogen by managing linepack swings more smoothly. In doing so, our technology improves the resilience of the network and overall energy security.

“This is of particular importance for a number of regions in the UK and particularly across Scotland, where there are no alternative or existing geological storage solutions.”

Wright adds that in addition to its clear application in the UK, Gravitricity’s underground storage technology is likely to be deployed more widely in export markets as other countries seek to deploy their own hydrogen solutions.

The Scottish Hydrogen Assessment’s ‘Green Export Scenario’ stated that Scotland could produce 3.3 million tonnes (Mt) of green hydrogen annually by 2045, with 2.5 Mt designated for export, and initial deliveries to mainland Europe expected before 2030. 

Gravitricity has separately completed commercial and technical feasibility work to confirm that H2FlexiStore can be deployed in this role.

For more information, visit www.gravitricity.com and www.nationalgas.com.