A CRITICAL phase of the €1.6 billion Celtic Interconnector project is now underway, with the start of subsea cable installation marking a key step toward creating Ireland’s first electricity link to mainland Europe.
The project, developed by Ireland’s EirGrid and France’s Réseau de Transport d’Électricité, aims to support renewable energy integration and stabilise electricity prices by enabling the flow of up to 700 megawatts (MW) of electricity between Ireland and France.
This is enough energy to power nearly half a million homes.
Cable laying began earlier this week off the coast of East Cork using the Norwegian specialist marine vessel Calypso.
The vessel is currently installing an 84 km stretch of high-voltage direct current (HVDC) cable along a carefully mapped route on the seabed.
Two additional vessels are handling the burial of the cable to protect it from marine activity and environmental impacts.
The full interconnector will span 575 km, with 500 km of undersea cable, linking Claycastle Beach in Co. Cork to the northwest coast of Brittany, France.
Once operational, it will serve as the only direct energy link between Ireland and continental Europe.
The Calypso, equipped with both deck and below-deck carousels capable of carrying up to 8,000 tonnes of cable, is performing the summer cable-laying operation during optimal weather conditions.
Marine survey teams had previously mapped the seabed to determine the safest and most efficient route.
Onshore, construction efforts continue at pace. Extensive ducting and trenching have been carried out between Claycastle and the Ballyadam converter station near Carrigtwohill.
Civil works at the 11-acre Ballyadam site, led by Siemens Energy, are nearly finished.
This station will convert HVDC electricity arriving from France into high-voltage alternating current (HVAC) for integration into the Irish grid via the Knockraha substation.
So far, 97% of trenching and ducting between Youghal and Ballyadam is complete, and three 200-tonne transformers are expected to arrive at the converter station later this month.
Meanwhile, HVAC cable installation between Ballyadam and Knockraha has been finalised, with road reinstatement works underway in collaboration with Cork County Council.
EirGrid’s Project Manager Shane Cooney said the interconnector has been in development for more than a decade and is now at a critical implementation stage.
“This project is of national significance and also holds importance at a European level,” said Cooney.
“It has secured over €500 million in EU funding, based on its potential to connect Ireland to the wider EU electricity market, balance power prices, and support the integration of renewable energy.”
EirGrid Chief Infrastructure Officer Michael Mahon echoed the sentiment, attributing the project’s smooth progression to strong collaboration between Irish and French teams, as well as local community support.
“This is a feat of engineering made possible by years of collaboration, innovation, and commitment,” Mahon said. “It’s a pivotal step in ensuring the future resilience of our energy system.”
Initially expected to be operational by spring 2028, recent updates suggest the Celtic Interconnector could be live as soon as next year, pending the timely completion of marine and onshore works.
Beyond reducing reliance on emergency electricity measures, EirGrid reports that the interconnector is expected to fill Ireland’s forecasted electricity capacity gap in 2027 and 2028.
However, further reinforcements may still be necessary to meet longer-term demand.
The Celtic Interconnector is being co-funded by the EU’s Connecting Europe Facility and forms a cornerstone of Ireland’s broader strategy to decarbonise its power system and integrate with the EU energy market.
See More: Celtic Interconnector, EU, Energy, Undersea Cables
