UK Energy Storage

The UK’s largest underground salt cavern HYDROGEN storage project

Portland Port Dorset

UKEn will build the UK's largest Hydrogen storage site, with up to 2 billion cubic metres capacity providing up to 20% of the UK’s predicted hydrogen storage needs in 2035, doubling the UK’s existing underground storage. It will also include a system level hydrogen battery to store excess renewable power for later peak power demand use.

Why UKEn?

Energy storage is a critical component of any energy network. Large-scale storage helps balance winter and other shorter term peak energy demands and provides insurance against critical supply disruption such as the War in Ukraine or extreme weather events.

UKEn has created an advanced project to provide up to 20% of UK 2035 strategic hydrogen storage needs plus a material scale hydrogen battery (see life cycle of a hydrogen battery).

A gas storage facility on the Isle of Portland has been considered for many years. In 2008, a project to build salt caverns for natural gas storage received planning approval. UKEn has revived and upgraded this project for the 21st century hydrogen economy, signing a lease with Portland Port and acquiring the Intellectual Property (IP) for the previous project.

The facility’s design has been improved and enhanced to minimise its carbon footprint, make it pure hydrogen ready and capable of full integration with green hydrogen production from offshore and onshore renewables from inception. Its cavern design includes the most modern safety considerations learned primarily from European salt cavern design and operation.

UKEn’s ultimate goal of 2 billion m³ of storage would be roughly equivalent to the storage provided by the offshore Rough gas field, which during its peak operational days provided around 70% of the UK’s underground natural gas storage capacity.

UKEn are proposing a hydrogen storage project on the Isle of Portland … the development of hydrogen storage infrastructure, including salt caverns, is a critical next step in the growth of the hydrogen economy.
Lord Callanan
We expect initial allocation of the storage business model to focus primarily on geological storage. We have reached this view as we consider that this type of storage is essential to establishing a hydrogen economy.
I think hydrogen will be used for storing energy – you won’t have to switch off wind farms at night when you don’t need power because you can turn into hydrogen and use it later.
JULY 2023

News & Insights

Latest news insights from UK Energy Storage about the Hydrogen sector.

SEEL offer their support for UKEn Hydrogen Storage plans 

Green hydrogen industry ‘is not just a lot of hot air’

Why UKEn’s storage?

National Grid’s Future Energy Scenarios (FES) illustrate the growing need for hydrogen storage, predicting a middle case requirement of around 10 billion m³ of storage by 2035. UKEn’s goal of 2 billion m³ by 2035 would supply 20% of this capacity. The upper case FES scenario cites a requirement of up to 30 billion m³ of storage

These levels of storage require the UK to have 4-10 times more than its current total gas storage capacity of 2.9 billion m³, of which c. 2 billion is underground storage, one of the lowest capacities within Europe.

Given that such underground salt cavern storage projects can take 5-8 years to achieve construction and operational readiness, the UK urgently needs to fast track, prioritise and support investment into this key enabling sector.

The cavern will be built 2,400m (approx. 1.5 miles) below ground level

Why is UKEn’s Hydrogen storage needed?

Hydrogen storage is required for four key reasons:

The H2 Economy will require ~4-10 times current UK 2.9bcm storage by 2035

Best H₂ Storage Solution - Salt Caverns

underground salt caverns are the best fit for our large scale system level hydrogen storage needs

Hydrogen infrastructure is in its infancy with both demand and supply increasing from its current very low base. Consequently, future hydrogen storage infrastructure needs to be flexible, preferably modular and capable of growing with each regional market’s needs.

Salt caverns are ideally suited to this purpose as they can be added as modules over a relatively short time frame and are a proven, reliable, and safe technology that has been used worldwide and in the UK for around half a century in the natural gas sector. Other forms of geological storage, such as depleted gas fields and aquifers are by their nature non-modular. Fortunately, the UK mainland is blessed with thick rock salt deposits suitable for large scale hydrogen cavern construction in three areas, Dorset, Cheshire and northeast Yorkshire.

Salt Caverns have been used for high purity hydrogen storage by the chemical sector in the UK since the 1970’s (Teesside) and in the US since the 1980’s (US Gulf Coast and Clemens Terminal in Texas) as well as Yakshunovskoe in Russia and Kiel in Germany.

Salt caverns are made by the dissolution of rock salt using either fresh or salt water (brine). In the case of Portland, UKEn intends to use sea water to dissolve the caverns. The rock salt deposits, primarily composed of the naturally occurring mineral halite, are highly impermeable to gas and thus provide an ideal and safe storage medium for hydrogen.

Underground storage sites have, by definition, a small low-rise surface footprint and characteristically have low operational costs and a high recovery efficiency compared to other forms of geological storage, such as depleted natural gas fields. UKEn’s Portland facility will be able to reinject almost 100% of the hydrogen stored back into the hydrogen network compared to around a 70% recovery efficiency for depleted gas fields, depending on the geological complexity of the field. The c. 30% of hydrogen that cannot be recovered from storage is known as “cushion gas” and in the case of a large, depleted gas field would equate to a significant non-recoverable sunk capital cost.

Sovereign Investment Support For Hydrogen Storage

Extracts from Department for Energy Security & Net Zero document:

Hydrogen transport and storage infrastructure: minded to positions

“Hydrogen can support the decarbonisation of the UK economy, particularly in ‘hard to electrify’ UK industrial sectors, and can provide greener, flexible energy across power, transport and potentially heat. Hydrogen produced in the UK could create thousands of jobs across the country, and provide greater domestic energy security, lowering our reliance on energy imports.”

Published in August 2023


The UKEn site is located on the Isle of Portland, between the South Wales and Southampton industrial hubs. Our unique salt cavern geological storage is positioned close to the Solent Cluster (UKEn are key members) and Hinkley Point nuclear and potential new offshore wind (e.g. 4GW Celtic Sea floating offshore wind). Portland is the closest large scale strategic storage facility to London and the densely populated South East.

Why Portland Port?

The UKEn site is located on the Isle of Portland, between the South Wales and Southampton industrial hubs.

The unique salt cavern geological storage is positioned close to the Solent Cluster (we are key members) and Hinkley Point nuclear and potential new offshore wind. 

Closest large scale strategic storage facility to London and the heavily-populated South East.

Portland Hydrogen Hub

A new hydrogen hub in Portland centred on UKEn’s system level storage facility will help address the current energy crisis and act as a key enabler for the Solent Hydrogen Cluster and a future Southern Super Hydrogen Cluster.

The initial construction of 19 new salt caverns will provide around 1 billion m³ of storage increasing the current UK onshore’s underground storage capacity by around 70%. A planned second phase, both in the adjacent offshore and onshore would add a further 1 billion m³ of storage.