Submarine Cable Laying Kicks Off for Celtic Interconnector — What This Game-Changer Means for Energy Markets and Your Investment Strategy

Ever wondered what it takes to literally connect entire countries beneath the ocean? Well, this week marks a mega milestone in energy innovation as the Celtic Interconnector project kicks off the laying of its submarine cable, linking Ireland and France’s electricity grids for the very first time. Picture this: a specialized vessel named Calypso arriving all the way from Norway, poised to lay an 84km stretch of high voltage direct current cable on the seabed, part of a grand 500km connection set to power nearly half a million homes. It’s not just engineering; it’s a high-stakes dance with the Atlantic’s moods, coordinated with local fisheries and marine experts to carve the perfect route. This isn’t your average infrastructure project — it’s a testament to collaboration, cutting-edge tech, and patience from communities on both sides. So, what’s the real impact of turning a sea between two countries into a supercharged energy highway? Let’s dive deep into this electrifying venture. LEARN MORE

A landmark moment was reached this week on the Celtic Interconnector project, as laying of the submarine cable commenced on the key energy project linking the electricity grids of Ireland and France.

The next phase of the project was signalled by the arrival of the specialist marine vessel Calypso, which will lay the high voltage direct current (HVDC) cable for the project, which is being developed with EirGrid and its French equivalent, Réseau de Transport d’Electricité (RTE) and co-funded by the EU Connecting Europe Fund.

When complete, it will be the first interconnector between Ireland and continental Europe, travelling from east Cork to the north-west coast of Brittany.

The vessel, which arrived from Norway in the Port of Cork, has started the cable laying along an 84km section of the route. 

When fully complete, the HVDC cable will span 500km from east Cork to the north-west of Brittany and will allow the exchange of 700MW of electricity, equal to powering 450,000 homes.

The cable is being laid onto the seabed by the Calypso, with burial works done by two further vessels.  

The cable lay and burial operations are weather sensitive and are being carried out in summer, to align with the best weather conditions. 

Marine survey teams have mapped the seabed in advance of works to chart the optimal route for the cable, with EirGrid liaising with local fisheries and marine users throughout.

Speaking about the marine campaign, Michael Behan said: “EirGrid is proud to welcome this latest phase of works on the Celtic Interconnector project, which really shows the progress being made on this key energy project for Ireland.

“This feat of engineering that will take place over the coming weeks is testament to the collaboration, innovation and care required to deliver this critical infrastructure.

“We remain grateful for the continued patience and support of communities, landowners, and stakeholders as we progress this project.”

The cable laying installation is just one element of this strategic infrastructure project being developed by EirGrid and its French counterpart, Réseau de Transport d’Électricité (RTE).

The project’s onshore phase has seen approximately 10km of high voltage alternating current (HVAC) cable installed in roads, with HVDC cabling works currently being progressed.

Meanwhile, civil works at the project’s converter station, located at Ballyadam, near Carrigtwohill, are near completion, with internal fitouts of the converter hall progressing well.

Photo: Cable laying vessel, Calypso, docked at the Port of Cork ahead of the cable laying campaign for the Celtic Interconnector project.