Arcadis delivers the civil engineering works for the electricity converter station of the electricity interconnection project between France and Ireland

Arcadis, international engineering and consulting company, is pleased to announce the delivery of the civil engineering lots for the Breton high voltage direct current (HVDC) electricity conversion station for the project Celtic Interconnector, led by CIDAC (RTE/EirGrid joint venture), which aims to enable a direct exchange of electricity between France and Ireland. As project manager, Arcadis was responsible for designing and supervising the station works (on the French side) for the civil engineering part, on behalf of Siemens Energy, the general contractor responsible for the design and acceptance of the work.

Critical to achieving a sustainable energy future, the HVDC stations, located on the north coast of Brittany and the south coast of Ireland, will convert alternating current from the electricity grids into direct current. They will be connected by a 575 km cable, approximately 500 km of which will be underwater.

With a capacity of 700 MW, the power line, once commissioned, is expected to supply nearly 450.000 homes in France and Ireland. It will strengthen the security and reliability of electricity supply, integrate more electricity from renewable energy sources into the grid, and reduce the cost of electricity. It will also help strengthen electricity solidarity between the two countries in the event of an incident.

For Johan Pavie, Building Development Director at Arcadis: "Consumption peaks are not necessarily the same in France and Ireland. Sharing the network allows energy to be sent where it is needed, and therefore strengthens the security of the electricity supply."

The HVDC station consists of several buildings, each with its own function: electrical conversion, control, and converter monitoring. Their design and construction relied on particularly advanced quality control.

For Stéphane Casolari, Project Manager at Arcadis: "The level of demand for an HVDC station is similar to that of a nuclear power plant. The economic and safety issues are such that the main challenge of our mission was to meet a very high level of quality."

In addition, special attention was paid to the project's environmental challenges. The facilities stand out for their environmental performance (BREEAM level) and their eco-design, with the use of a majority of low-carbon concrete and recycled materials, such as recycled steel for 90% of the framework.

The project mobilized the multidisciplinary skills of Arcadis, both in the design phase (environmental and sustainable development studies; earthworks; foundations; civil engineering; metal framework; lighting, roads and various networks for exterior developments; heating, electricity and coatings for interior developments) and in the works management phase with quality and risk control, and cost, schedule and contract management.

For Johan Pavie: "The Arcadis teams are proud to participate in this industrial project serving the general interest, which will help accelerate the shift towards a low-carbon electricity mix and strengthen Europe's energy independence."

Following Arcadis' delivery of the station's civil engineering works, Siemens Energy will still need to implement and test the high-voltage direct current (HVDC) transmission process, before commissioning is scheduled for the end of 2026. The interconnection to the electricity market is expected to open in the first half of 1.

For Alexandre Pinson, Project Director at Siemens Energy: “The development of electrical interconnections is an important lever for the energy transition, allowing consumers to benefit from a more open electricity market. We thank all of our partners who are working alongside us to build a lower-carbon future. And we congratulate the Arcadis teams for their rigor and project management, which enabled the station to be delivered on schedule and in accordance with very demanding specifications.”

The Celtic Interconnector project in figures

• 700 MW of total electrical exchange capacity, enough to supply electricity 450.000 homes in France and Ireland
• 575 km of electric cables, including approximately 500 km underwater
• 1,623 billion euros : total cost of the project
• 530,7 million : amount of the grant awarded by the European Commission which supports the project

The main players in the project

• RTE, the electricity transmission network manager in France and its Irish counterpart, EirGrid : project owners
• Siemens Energy : general contractor responsible for project supervision and supplier of high voltage direct current (HVDC) transmission technology
• Arcadis : project manager (all-trades engineering and works management)
• NGE / VILQUIN / SNEF : main construction companies