Celtic Interconnector, uniting Irish and French electricity grids
Celtic Interconnector: Construction of the converter stations in both countries — with the station on the Irish side located in Ballyadam, east Cork — are substantially complete, with AC and DC cable terminations complete, including transformers and reactors installed.
Construction of the Celtic Interconnector is continuing offshore, with around 500 people now working in Irish and French waters to deliver the key cross-border energy project.
Alongside this offshore progress, EirGrid, the operator and developer of Ireland’s electricity grid, has marked a significant onshore milestone in Ireland, with all onshore cables for the project now successfully installed.
The Celtic Interconnector will create an electrical interconnection between Ireland and France, enabling the exchange of 700 MW of electricity between the two countries, equal to powering around 450,000 homes.
Moving this electricity across a distance of 575km, the 500km of subsea cable will run from east Cork to the north-west coast of Brittany.
EirGrid is developing the project with its French equivalent, Réseau de Transport d’Electricité (RTÉ). When delivered, it will be the first interconnector between Ireland and continental Europe.
Significant progress has been made to date on the project, both on the Irish and French sides.
In Ireland, the final onshore cable is now successfully installed at the transition joint bay at the landfall in Youghal, east Cork, where the marine cable will come ashore.
This now means a total of 44km of onshore cable is in place and jointed, ready to receive the marine cable once the offshore cable works are complete.
“The onshore cable for the Celtic Interconnector is now complete, which is another key step forward in connecting Ireland and France. This latest milestone is a result of months of careful planning and coordination with our contractors, and thanks to the cooperation of the local community in Youghal in reaching this point,” said Michael Behan, EirGrid’s Chief Financial Officer and Director of the Celtic Interconnector Designated Activity Company (CIDAC), a joint venture between EirGrid and RTÉ France.
Construction of the converter stations in both countries — with the station on the Irish side located in Ballyadam, east Cork — are substantially complete, with AC and DC cable terminations complete, including transformers and reactors installed.
In France, the energisation of the 400kV cable between the converter station and the grid connection point has commenced.
The marine campaign is continuing and the scale of activity currently under way is significant.
A key part of the operation is three trenching vessels – Aethra, Athena and Argo – with seven cable guard vessels providing support.
These specialist vessels are carrying out subsea cable burial activities along the marine route between Ireland and France, an important step in protecting the installed high voltage direct current (HVDC) cables.
The first marine cable laying campaign, by the Calypso vessel, saw 84km of HVDC cable installed in Irish waters in 2025. The second marine cable laying campaign has commenced off France in recent weeks, with the cable successfully pulled into the transmission joint bay at the landfall location.
“Marine works are widely recognised as one of the most challenging elements of any interconnector project, with complex marine works that involve the manufacture and burial of bespoke marine cables. They require specialist vessels, highly skilled crews, while being carefully planned around weather conditions and environmental considerations,” Behan continued.
“On the Celtic Interconnector, this is the most complex part of the overall programme, given the length of the route.” As a direct result of new planned marine operations, the project’s commissioning date is now expected for Q4 2028.
Adverse weather conditions could impact this date, as offshore works can only be carried out safely and effectively under the right conditions.
The Celtic Interconnector is supported by European Union funding through the Connecting Europe Facility (CEF), administered by the European Climate, Infrastructure and Environment Executive Agency (CINEA).
In recognition of the communities hosting this critical project, EirGrid is also progressing with the Community Benefit Fund associated with this infrastructure.
Last year, phase 2 of the fund saw a total of €821,265 awarded to community groups and not-for-profit organisations in the project area.
Further showing the commitment to strengthening Ireland’s interconnection with our European neighbours, the feasibility and benefits of an Ireland-Spain interconnection are also being explored. A Memorandum of Understanding was recently signed between the Department of Climate, Energy and the Environment and the Spanish Government to explore the potential for future electricity interconnection between Ireland and Spain.
EirGrid CEO, Cathal Marley, said: “The Celtic Interconnector is part of developing an integrated energy system for Europe, helping to achieve affordable, secure, and sustainable energy for all citizens, and both EirGrid and RTÉ France remain committed to the delivery of the project.
“Reaching this stage in construction of this interconnector is a testament to the dedication and collaboration from all stakeholders, and we look forward to progressing this landmark project,” Marley added.
Find out more at Eirgrid.ie/celticinterconnector.
