Menu

Ireland's sailing, boating & maritime magazine

RBC Brewin Dolphin proudly supporting Afloat and Irish Boating

Celtic Interconnector Marks Two Years of Construction Progress

4th December 2025
“Four
Four 240-tonne transformers arrive at Aghada Power Station in Cork for installation on the Celtic Interconnector, marking a major logistics operation and supporting the next stage of the cross-border electricity project.

Construction on the Celtic Interconnector has passed the two-year mark, according to project partners EirGrid and Réseau de Transport d'Électricité.

The subsea link will connect the electricity grids of Ireland and France. It is co-financed by the EU’s Connecting Europe Facility.

EirGrid reports that more than 60 per cent of the high-voltage direct current cables are now installed onshore in Ireland. The first 84 kilometres of marine cable have also been laid.

Four transformers, each weighing 240 tonnes, were delivered to the project in recent weeks.

EirGrid and RTE marked the milestone at PCI Energy Days in Brussels. They briefed Mechthild Wörsdörfer, deputy director-general at DG Energy, and MEP Barry Andrews on progress.

EirGrid’s Shane Cooney and chief financial officer Michael Behan join MEP Barry Andrews and RTE’s Rémi Courtial as they discuss recent construction milestones and the next phases of the Celtic Interconnector at the Brussels energy event.EirGrid’s Shane Cooney and chief financial officer Michael Behan join MEP Barry Andrews and RTE’s Rémi Courtial as they discuss recent construction milestones and the next phases of the Celtic Interconnector at the Brussels energy event.

Local communities in east Cork continue to receive support through the Celtic Interconnector Community Benefit Fund. More than €1.6 million has been awarded to community and not-for-profit groups, including €830,000 in the second phase of funding this year.

“We have seen significant progress on the project over the last two years thanks to the collaboration of contractors, partners and especially to the communities of east Cork,” said EirGrid chief financial officer Michael Behan.

He said the organisation aims to “deliver a cleaner energy future” and expects further milestones in 2026.

When complete, the interconnector will enable the exchange of 700 MW of electricity between Ireland and France, enough to power 450,000 homes.

Members of the Celtic Interconnector project team, Pádraig Slyne and Shane Cooney, meet Mechthild Wörsdörfer, deputy director-general at DG Energy, during PCI Energy Days in Brussels to outline progress on the Ireland–France subsea link.Members of the Celtic Interconnector project team, Pádraig Slyne and Shane Cooney, meet Mechthild Wörsdörfer, deputy director-general at DG Energy, during PCI Energy Days in Brussels to outline progress on the Ireland–France subsea link.

Published in Undersea Cables
Afloat.ie Team

About The Author

Afloat.ie Team

Email The Author

Afloat.ie is Ireland's dedicated marine journalism team.

Have you got a story for our reporters? Email us here.

We've got a favour to ask

More people are reading Afloat.ie than ever thanks to the power of the internet but we're in stormy seas because advertising revenues across the media are falling fast. Unlike many news sites, we haven't put up a paywall because we want to keep our marine journalism open.

Afloat.ie is Ireland's only full-time marine journalism team and it takes time, money and hard work to produce our content.

So you can see why we need to ask for your help.

If everyone chipped in, we can enhance our coverage and our future would be more secure. You can help us through a small donation. Thank you.

Direct Donation to Afloat button

Undersea Cables

Undersea cables are vital to Ireland's connectivity, facilitating high-speed internet, telecommunications, and energy transmission. These cables traverse the Irish Sea, connecting Ireland to the United Kingdom and continental Europe, and play a crucial role in global communications.

Submarine Communications Cables:
Ireland is strategically positioned along major transatlantic communication routes. Approximately 75% of transatlantic cables pass near Irish waters, underscoring the nation's significance in global data transmission.
These cables are typically as wide as a garden hose, with the filaments that carry light signals being extremely thin—roughly the diameter of a human hair. They are sheathed in layers of insulation and protection, with cables laid nearer to shore using extra layers of armoring for enhanced protection.

Energy Interconnectors:
In addition to communication cables, undersea interconnectors are being developed to enhance energy security and support the transition to renewable energy sources. The UK has approved the construction of five new subsea interconnector cables to boost the grid's flexibility amidst rising renewable energy. These projects will link the UK with wind farms in Belgium and the Netherlands, and connect England with Germany, Wales with Ireland, and Scotland with Northern Ireland. The cables, with a combined 6GW capacity, are expected to be operational by 2032, increasing the UK's total interconnector capacity to 18GW.

Security Concerns:
The strategic importance of these undersea cables has raised security concerns. Incidents in the Baltics have heightened awareness about the potential risks to subsea infrastructure. Ireland's historical neutrality and limited defense resources have led to calls for enhanced maritime security and defense investments, including modern surveillance technology and international cooperation. The government's response includes participation in EU security projects and collaboration with neighboring countries on maritime security.

In November 2024, a Russian spy ship, the Yantar, was escorted out of the Irish Sea by the Irish navy after it was found patrolling an area with critical submarine pipelines and cables. The vessel's presence heightened concerns due to its proximity to interconnector cables vital for internet services linking Ireland to the UK, operated by major tech companies such as Google and Microsoft.

Regulatory and Policy Framework:
The protection and maintenance of undersea cables fall under the jurisdiction of national governments, with private companies often responsible for their security. In Ireland, the Department of Communications, Climate Action and Environment oversees the regulation of telecommunications infrastructure, including undersea cables. The Irish Naval Service plays a role in monitoring and protecting maritime infrastructure, including undersea cables. Internationally, the United Nations Convention on the Law of the Sea (UNCLOS) provides a framework for the laying and maintenance of submarine cables, recognizing the "freedom of the seas" and the rights of coastal states.

Conclusion:
Undersea cables are indispensable to Ireland's connectivity and economic infrastructure. Given their strategic importance, ongoing efforts are necessary to ensure their protection and resilience against potential threats. This includes enhancing security measures, international cooperation, and adherence to regulatory frameworks to safeguard these critical assets.