A controversial pylon project for the west may be shelved amid concerns that a windfarm proposed by the ESB and Bord na Mona may not be large enough to justify the works.
It is understood that national grid operator EirGrid has written to the companies seeking clarification around the size of the Oweninny wind farm, planned for Bellacorick in Co Mayo, which is currently in planning.
The companies have sought permission for a 112-turbine farm, which would require the transmission system to undergo a substantial upgrade at a projected cost of €200m if the 100km line is erected on pylons, and up to €500m if undergrounded.
The upgrades are needed so power can flow from the wind farm into the national grid.
Oweninny was expected to produce 370MW of electricity, enough for around 315,000 homes.
But it is understood that the project may be scaled back to just 170MW – sufficient for around 145,000 properties.
It comes after a High Court judgment handed down late last year meant that in-depth environment assessments were required not only for windfarm projects, but on the planned grid connection also.
An Bord Pleanala has sought further information on Oweninny from the developers, which may result in the project being scaled back because the grid connection has not been finalised.
Sources said that the project was expected to be reduced in scale, which would result in “implications” for the Grid West project.
This is because Grid West is being developed to connect Oweninny, and other large windfarm projects in north west Mayo to the grid.
A significant reduction in the levels of wind energy being produced could result in the project being considered unviable.
Clarification has been sought from the companies by the end of next January.
“EirGrid has written to Bord Na Móna seeking clarification on their position in the long term,” the grid operator said.
“EirGrid will then determine whether the Grid West project is proceeding or should be altered or discontinued.”
It is understood that additional information on the project has been submitted to An Bord Pleanala, and is expected to be published in the coming weeks.
Both ESB and Bord na Mona refused to comment, saying it would not be appropriate as the project was in planning.