The University of Aberdeen has expressed concerns over the potential of a decommissioned gas field in Scotland as a major hydrogen store.
Alongside the UK Onshore Geophysical Library, it carried out a study into the Cousland gas field in Midlothian. From this, it found it failed to meet the criteria for safe substance storage, owed to a lack of evidence around the nature of the subsurface sedimentary rocks and the structure of the field. This means there are concerns around the potential for hydrogen to escape and then present a risk to the local environment and surrounding communities.
Hydrogen can be safely stored in subsurface geological sites, though to date this has been largely limited to man-made hermetically sealed soluble caverns in rock salt deposits. With an abundance of salt deposits onshore in Scotland, this led to putting forward former and depleted hydrocarbon fields.
With no natural hydrogen discovered in any existing onshore or offshore fields in the UK, Professor John Underhill, who led the study, suggested it raises the question as to whether or not it was once there and leaked – “and crucially if it would stay underground if it was injected into a subsurface site”.
Underhill further said that the study had shown just how important it is for independent evaluation of subsurface sites proposed for the use of hydrogen storage as part of the energy transition. Underhill continued: “In this particular case, it emphasizes the storage challenges associated with porous media in general and in subsurface sites in onshore areas in particular”.
