The ‘multiplier cost’ of undergrounding 400kV electricity cables as opposed to running them overground ‘cannot be stated with certainty’ according to Labour TD Ciara Conway.
Speaking in the Dáil on Tuesday last, the Waterford Deputy stated: “On the basis of the information available to me, I cannot say for certain that undergrounding other 400kV lines in Grid25 would automatically be three times as costly.
“In Europe, overhead is the norm for high voltage transmission infrastructure, although there is undergrounding of a small fraction of such infrastructure for various reasons.
“This does not obviate the fact that undergrounding remains the much more expensive option and it is considered to reduce system security.”
Deputy Conway added: “EirGrid is, under its licence, obliged to plan the transmission network in the most safe, secure, economic and reliable way possible.
“EirGrid has stated that underground cables are less reliable and more costly and can introduce technical difficulties, and that underground DC cables are not the right fit from a technical perspective on major projects such as the 400kV proposals.”
Deputy Conway told the Dáil: “Reference has been made to DC underground cable schemes in service in Europe today, including our own East-West Interconnector. But the fact is that these all involve submarine crossings.
“A few on-land schemes are planned, for example in France to Spain, but these are not representative of the transmission system in Ireland because they will be interconnectors between two different grids, as opposed to being part of a meshed, backbone, grid as we have.”
However, she added: ” I am aware that many people are concerned about the impact that new transmission lines and other energy infrastructure can have on the landscape, the environment and on local communities.
“I have repeatedly said it is essential that Grid25 and other energy infrastructure plans are taken forward on the basis of the best available knowledge and informed meaningful engagement on the impacts and costs of the various options.”