EDF Energy is to bring ten large salt caverns into use as fast retrieval gas storage facilities, boosting land-based facilities in the UK.
The scheme is part of a push by energy firms to meet the Government’s target to quadruple current underground gas storage by 2021 to cope with extreme weather events such as the recent bout of cold weather.
The caverns, which have maximum diameters greater than the London Eye, are located near Warmingham, north of Crewe in Cheshire. They were bought by EDF Energy in April 2010 from British Salt and will be capable of supplying enough gas to meet the needs of three million average households.
Each cavern is typically around 600,000 to 650,000m3 and when in operation from the spring gas will be drawn from them equally and supplied back to the Grid.
EDF Energy is being advised by Dr Evan Passaris of Atkins, who has worked on underground storage schemes in Italy, Germany, the Netherlands and Denmark, and he is acknowledged as a leading expert on underground gas storage. He says the increasing use of salt caverns will provide a major boost to the UK’s ability to respond to prolonged cold snaps.
“Salt caverns provide ideal underground gas storage facilities as the geological make-up of the thick layered impervious salt formation creates an ideal gas-tight container,” he said.
“The advantage of using these over other forms of natural storage, such as porous rock found in depleted oil and gas reservoirs, is that salt cavern stored gas can be delivered in large quantities relatively quickly. The caverns are also comparatively easy to fill and it is will be possible to retrieve almost all of the stored gas when eventually the facility will be decommissioned.”
Converting the former salt caverns in Warmingham began with an initial geomechanical assessment of each of the ten cavities to ensure its structural integrity complied with strict safety criteria. A second access borehole was then drilled to allow the caverns to be filled with gas from the National Grid in order to flush out the residual brine - a process that process has just begun.