The Salinae Hydrogen Storage project is the potential development of a salt cavern hydrogen storage facility, near Warmingham in Cheshire, a few miles from Uniper’s existing gas storage facility at Holford.

Uniper and British Salt have agreed a Feasibility Development Agreement which gives Uniper the sole rights to explore the site’s potential for hydrogen storage. British Salt will add steps to its existing solution mining plans to support Uniper in gathering data with the aim of evaluating the site’s potential.

The site has the potential to store up to 400GWh of hydrogen¹  across up to 13 caverns. This could help to provide confidence for industries looking to fuel switch to hydrogen and away from fossil fuels, by providing a reliable source of hydrogen, complementing other sources.

Uniper is also exploring the potential to include hydrogen production capability as part of the Salinae Hydrogen Storage project. This would likely include up to 50MW electrolytic (green) hydrogen production, directly connected to the proposed storage facility. 

The project will be subject to Uniper being granted a development consent order (DCO) for a hydrogen facility. In the absence of a hydrogen market, and as a precursor to a competitive market framework, Uniper will also need UK Government to develop a bespoke business model to bring forward this first of a kind technology. 

Any future arrangements for the storage or use of hydrogen would be subject to further agreements if the project progresses beyond the feasibility stage.

Hydrogen is a key fuel for industries that are difficult to electrify, such as chemical production and refining, steelmaking, cement production, and transport. Once produced, hydrogen can also be refined into renewable liquid fuels – such as synthetic diesel and sustainable aviation fuel – providing a clean energy source for vehicles and whole industries that currently rely on carbon-intensive fuels. 

Hydrogen storage offers the potential to store renewable energy, enabling excess wind and solar power to be utilised for hydrogen production, rather than being curtailed as is currently the case. Underground cavern storage systems for hydrogen can compensate for short-, mid- and long-term fluctuations in production and demand, and are very efficient due to their rapid injection and withdrawal capabilities.

Uniper is already investigating the potential for future hydrogen storage with two pioneering pilot projects in north-west Germany, one of which will provide valuable experience for the Salinae Hydrogen Storage project. The Hydrogen Pilot Cavern Krummhörn project is a salt cavern storage facility which we have established in order to test the construction and operation of a 100% hydrogen storage facility under real conditions. The work to develop hydrogen-ready caverns took place during the first half of 2024 and the facility was opened in August 2024.

Developing sufficient storage capacity in the UK will require existing underground facilities to be converted to meet demand and new facilities, such as the Salinae Hydrogen Storage project, to be built. 

Cheshire, including the area around Warmingham, has a geology that is highly favourable for salt cavern gas storage which would be able to significantly contribute to the large-scale seasonal and daily flexibility needs of the UK's future energy system.

Salt extraction in the region dates back to Roman times and the area has also been home to salt cavern gas storage facilities for a number of years. Uniper’s Holford gas storage facility at Byley has been in operation since 2011.

The development of a hydrogen storage facility could create opportunities during the construction phase and once it becomes operational, provide permanent jobs. It could also help to safeguard jobs in the wider area, by providing confidence for industries looking to fuel switch to hydrogen and away from fossil fuels, by providing a reliable source of hydrogen, complementing other sources.

If consented and developed, the proposed hydrogen storage facility could help to support the decarbonisation and economic growth of the region, supporting industrial customers to transition to a net zero future. 

The caverns would be created by a process known as solution mining, which involves injecting water into the salt beds to create a brine solution. British Salt has been applying this method on the same brinefield for over 50 years. If the Salinae Hydrogen Storage project is consented and developed, Uniper's proposal is for hydrogen gas to then be injected into the cavern, pumping out the brine. Only the hydrogen then remains in the cavern, creating a working storage facility. The displaced brine would be used in the production of salt at British Salt’s Middlewich plant.

The UK has a geology that is highly favourable for salt cavern gas storage which would be able to significantly contribute to the large-scale seasonal and daily flexibility needs of the UK's future energy system. Uniper's existing gas storage facility, and any potential future hydrogen storage facility, play a key role in ensuring a secure and flexible energy system in the UK.