Gas storage

We operate two salt cavity natural gas storage sites on the East Yorkshire coast, at Hornsea and Aldbrough. To form gas storage cavities, salt deposits around 2km under ground are leached by seawater (a process of pumping water from the North Sea into the salt, dissolving the salt and returning the brine to the North Sea). At the end of the process, up to 4 years, the water in each of the cavities created is replaced (dewatered) by gas under pressure. Around 45% of the gas must remain in the cavity for the life of the site, the remaining 55% is available for storage services.

Hornsea is currently the UK's largest onshore gas storage facility and has nine salt cavities, 325mscm of gas storage, fully utilised for commercial operations. Services from Hornsea are offered for use by the energy industry.

Aldbrough is in the final stages of its development, with the surface plant and six of the nine cavities already in operation.  Leaching at the remaining three caverns has been completed and they are now being de-watered through injection of gas. They should be ready for operation by the summer of this calendar year.

They will ultimately give the opportunity to store around 330mscm of gas, at an injection rate of up to 20mscm/d and a withdrawal rate of up to 40mscm/d. The Aldbrough site, operated by SSE Hornsea Ltd, is a two thirds / one third joint venture between SSE and Statoil (UK).When complete, SSE will have invested a total of around £290m in this development