What is the purpose of the Interconnector between France and Ireland?
The aim of the Celtic Interconnector is to link the Irish grid to the mainland European grid, with a continuous DC link, 575 km in length between Cork in Ireland and Brittany in France. The electrical link ensures power transmission in both directions: Ireland – France and France – Ireland.
This project will thus contribute to the European target for energy transition and addressing climate change. It will thus foster sustained development of wind power in Ireland and its integration in the European electricity system. In France, this new interconnection will ensure consumption of green electricity routed from Ireland. It thus constitutes a driver to support energy transition by facilitating change in the electricity mix.
The Celtic Interconnector Project will also contribute to strengthened security of power supply between the two countries, ensuring mutual support in the event of unforeseen circumstances (severe weather, technical incidents and peak consumption).
In broader terms, the project contributes to European electricity solidarity and shall enable Ireland to access the integrated European electricity without any curbs, within the context of Brexit.
Recognised as a project of common interest by the European Union in October 2013, with the label renewed in the 2017, the Celtic Interconnector Project fits in with the development of electricity interconnections – one of the drivers to support energy transition in France, Ireland and Europe.
In France, the project is part of the Ten Year Network Development Plan (TYNDP) set up in 2012. It is also featured in the EirGrid development plan.
What does the Celtic Interconnector Project entail?
The Celtic Interconnector Project plans to link the Knockraha substation (Cork) to the La Martyre substation (Finistère), with a DC underground circuit, with capacity of 700 MW, over a distance of approximately 575 km, including 500 km off shore.
In more concrete terms, the project is made up of:
- A connection to the existing 400 kV substation in La Martyre
- A converter station in France built in the immediate vicinity of the La Martyre substation. Installed on a plot of land of around 4 hectares, the buildings occupy approximately 5,000 m2 and are about 20 m in height. This station transforms DC into AC (and the other way round) to ensure connection to the French transmission grid.
- A submarine circuit, approximately 500km in length placed on or beneath the seabed between France and Ireland
- A landfall point where the submarine circuit comes onshore
- A HVDC land circuit between the landfall and a converter station. As this will be HVDC, it is proposed to use an underground cable for this element
- A converter station, to convert the electricity from HVDC to High Voltage Alternating Current (HVAC), which is used on the transmission grid. This station does not need to be in close proximity to the connection point on the grid
- A HVAC land circuit between the converter station and the connection point to the grid. This circuit can be underground cable or overhead line. However as it is HVAC there are limits to the length of cable that can be installed underground
- A connection point to an existing substation on the transmission grid
What are the project stages?
The Interconnector is planned to go live in 2026. Since 2012, RTE and EirGrid have undertaken technical and environmental studies (especially concerning the maritime route), which confirm the technical feasibility of a DC submarine and land circuit between France and Ireland.
In 2017 and 2018, RTE conducted preliminary consultation with the stakeholders, mainly local representatives, such as State Departments, parishes, elected officials and non-governmental organisations) affected by the circuit landfall point and land circuit. The purpose of these discussions is to be receptive to the territorial representatives, concerning their medium and long-term development and growth plans.
The consultation was resumed in autumn 2018, in compliance with the provisions effective in France and the European Union Regulations for European energy infrastructure. Its purpose is to validate the study area and the lowest impact zone for the underground circuit in France. Large-scale consultation will also be run under the auspices of the two guarantors appointed by the National Public Hearings Commission (CNDP), based on referral by RTE.
- Consultation: 2018-2019
- Impact assessment and public inquiry: 2019-2020
- Authorisations: 2022
- Procurement and work: 2022-2025
- Tests and commissioning: 2026