Salt Caverns

Why Portland Port?

The UKEn site is located on the Isle of Portland, between the South Wales and Southampton industrial hubs. It is the closest large scale strategic geological storage facility to London and the heavily populated South East.

It is positioned close to the Solent Cluster (of which UKEn are key members), Hinkley Point C nuclear and potential new over the horizon offshore wind off Portland Bill and the SW approaches. It lies above a regionally extensive rock-salt deposit that can hold multiple large salt caverns for hydrogen storage.

Salt Cavern Locations

The UK Mainland has three areas underlain by regionally extensive thick Triassic or Permian age rock salt deposits; Dorset (Triassic), the Northwest (Triassic: Cheshire and West Lancashire) and the Northeast (Permian Zechstein: mainly in east and northeast Yorkshire). These deposits also extend into the adjacent offshore and provide sufficiently thick and laterally extensive strata suitable for manmade salt cavern construction. In Portland’s case the Triassic salt sequence is over 450 metres thick, with the Dorset Halite member providing over 100 metres of continuous massive salt, in which multiple large 50-100 million m³ caverns can be dissolved. UKEn’s planned caverns within the Dorset Halite are approximately lozenge shaped with a height and width of 90-100 metres, encompassing roughly the same volume as St Paul’s cathedral in London.

The depth to the Triassic and Permian salt horizons across the UK varies from c. 500 metres in Cheshire to up to 2,000-2,400 metres at Portland and areas of NE Yorkshire. The Triassic salt of Dorset lies closer to surface in the onshore area to the north of Portland.

Fortunately for the UK, these salt deposits lie under or within close proximity to the main industrial hubs that will provide early hydrogen demand and related generation capabilities. UKEn’s Portland site is the first planned salt cavern site in Dorset in the south of England and lies adjacent to the Solent Cluster, of which UKEn is a key part and which seeks to decarbonise Southampton and the Solent area. Both the Hynet (Triassic salt) and East Coast Cluster (Permian salt) have access to smaller existing caverns (used for natural gas) and planned new hydrogen salt cavern storage sites. The UK’s existing and other planned sites are about half the size as Portland’s phase I target of 1 billion m³.

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.