The 400-kilovolt Itxaso-Castejón high-voltage line has been authorized.

The Directorate General for Energy Policy and Mines of the Ministry for the Ecological Transition and the Demographic Challenge has granted Red Eléctrica de España, SAU the prior administrative authorization and construction authorization for the 400 kV double-circuit overhead power transmission line Itxaso-Castejón/Muruarte, and has specifically declared its public utility. The resolution, signed on 28 July 2026 by the Director General Manuel García Hernández, is published in the Official Gazette of Navarra issue 160, of 14 August 2026, page 29933 (reference SGIISE/Resolución AAP-AAC-DUP-DIA LAT Itxaso-Castejón/Muruarte). In the same issue, page 29965, the authorization for the closure of the 220 kV lines Itxaso-Orcoyen 1 and 2 is published.

The project was requested by Red Eléctrica on 10 June 2021 and consists of an overhead line of 93.213 kilometers (92.484 km from the initial project plus the addendum of April 2025) that will connect the Itxaso substation, in Ezkio-Itsaso (Gipuzkoa), with the Castejón (Castejón, Navarra) and Muruarte (Tiebas-Muruarte de Reta, Navarra) substations. The action is included in the Development Plan for the Electricity Transmission Grid 2021-2026, approved by Resolution of the Council of Ministers of 22 March 2022, and has an environmental impact statement of 13 November 2023 (BOE issue 280, of 23 November 2023).

A key infrastructure for the Navarra-Basque Country axis

The resolution justifies the new line by the needs for integrating renewables and resolving technical restrictions on the new Navarra-Basque Country axis. Its main characteristics:

• Three-phase alternating current at 50 Hz, nominal voltage of 400 kV (maximum grid voltage: 420 kV) and double circuit.
• Three conductors per phase type AL/AW CONDOR, with a thermal capacity of 2,080 MVA per circuit in summer and 2,440 MVA in winter.
• Lattice steel towers, glass insulation and individual pad foundations.
• Includes the modification of span 210-211 of the 400 kV Barcina-Itxaso line and the dismantling of the 220 kV Itxaso-Orcoyen 1 and 2 lines.

Public utility and affected municipalities

The declaration, in particular, of public utility entails, in accordance with article 56.2 of Law 24/2013, of 26 December, on the Electricity Sector, the occupation of the assets and rights listed in Annex II of the resolution, which updates the list published in BOE issue 216, of 9 September 2021, in BON issue 216, of 14 October 2021, and in the Official Gazette of Gipuzkoa issue 182, of 22 September 2021. Affected municipalities:

• Navarre (23): Barasoain, Artaxoa, Añorbe, Eneritz, Adiotz, Muruzábal, Uterga, Legarda, Zizur, Oltza Zendea, Itza, Arakil, Irañeta, Uharte-Arakil, Arruazu, Lakuntza, Arbizu, Ergoiena, Etxarri Aranatz, Bakaiku, Iturmendi, Urdiain and Altsasu.
• Gipuzkoa (7): Parzonería General de Guipúzcoa y Álava, Idiazabal, Segura, Zerain, Mutiloa, Gabiria and Ezkio-Itsaso.

The allegations submitted by several municipal councils and local councils have not been taken into consideration because their purpose goes beyond the technical conditions of Royal Decree 1955/2000, of 1 December, in accordance with opinion 1251/2024 of the State Legal Service. An administrative appeal may be lodged against the resolution before the Secretary of State for Energy within one month.

Closure of the 220 kV Itxaso-Orcoyen lines

On the same date, the Directorate General for Energy Policy and Mines granted Red Eléctrica the closure authorisation for the 220 kV, single-circuit lines Itxaso-Orcoyen 1 and 2 (reference SGIISE/DED/Resolución Cierre L220 kV Itxaso-Orcoyen 1 y 2), of 57.95 and 62.77 kilometres respectively. The decommissioning plan provides for:

• Circuit 1: dismantling of 235 supports between the Orcoyen substation and support T-234 (54.66 km).
• Circuit 2: dismantling of 174 supports between support 1 and the Orcoyen substation (62.37 km).
• The sections shared with the in-service lines Itxaso-Ormaiztegui 1 and Itxaso-Elgea are retained.

Red Eléctrica has twelve months to carry out the closure and dismantling, counted from the grant of the operating authorisation for the new 400 kV line. The system operator has made the decommissioning of the 220 kV lines conditional on the prior commissioning of the 400 kV double circuit, to guarantee security of supply and the energy exchange capacity with France.

Relevance

The 400 kV Itxaso-Castejón/Muruarte line is the centrepiece of the reinforcement of electricity transmission between Navarre and the Basque Country: it will make it possible to evacuate renewable generation, resolve technical restrictions on the system and dismantle nearly 117 kilometres of 220 kV lines. For landowners in the 23 affected Navarrese municipalities, the declaration of public utility implies the occupation of the assets listed in Annex II, a prior step for the execution of a project declared to be of general interest.

Source: Official Gazette of Navarre, number 160, of 14 August 2026, p. 29933 (official reference: SGIISE/Resolución AAP-AAC-DUP-DIA LAT Itxaso-Castejón/Muruarte) and p. 29965 (official reference: SGIISE/DED/Resolución Cierre L220 kV Itxaso-Orcoyen 1 y 2).