The Supreme Court establishes case law on the environmental assessment of wind farms that share facilities: The mere fact of sharing does not determine the unity of the project

The recent Supreme Court Judgment 651/2026 of 27 May, handed down by the Contentious-Administrative Chamber of the Supreme Court in the context of the appeal lodged against the judgment that annulled the prior administrative authorisation and the construction permit for the Bustelo wind farm (A Coruña). It establishes clear legal precedents on three issues that had been generating intense litigation in the wind energy sector, particularly in Galicia: the environmental assessment of wind farms sharing infrastructure, the possibility of reducing public consultation periods, and the timing for obtaining sectoral reports in the environmental assessment procedure.

The High Court of Justice of Galicia had annulled the authorisations for the Bustelo wind farm, developed by Greenalia, on the grounds that the three wind farms by the same developer in the area (Campelo, Bustelo and Monte Toural) actually formed a single project that should have been assessed  environmentally as a whole, that the public consultation period had been unlawfully halved, and that the sectoral reports should have been included in the file before the public consultation procedure was opened. The Supreme Court has quashed that judgment in its entirety and confirmed the legality of the prior administrative authorisation and the construction permit for the Bustelo wind farm.

As regards the first issue, the Supreme Court rejected the argument that the mere sharing of grid connection facilities between two or more wind farms automatically requires them to be processed as a single project with a joint environmental assessment. The decisive factor is not the fact of sharing infrastructure — a common practice promoted by the regulations themselves to reduce environmental impact — but whether that separate processing has resulted in a real dilution of environmental control. In this case, each wind farm was subject to the most rigorous environmental assessment (the standard one), including a specific study of the cumulative and synergistic effects between the three, meaning there was no reduction in environmental safeguards of any kind.

Regarding the reduction of the public consultation period, the Supreme Court confirms that the Autonomous Communities may halve this period for projects declared to be of special interest or requiring urgent processing. The national provision setting a minimum of 30 days is not mandatory for regional authorities. Likewise, the minimum period of 30 days established by the European Environmental Impact Assessment Directive (Directive 2014/52/EU of the European Parliament and of the Council of 16 April 2014 amending Directive 2011/92/EU on the assessment of the effects of certain [OC2.1 ]public and private projects on the environment) refers exclusively to consultation with the ‘public concerned’ as persons with a proven interest in the procedure, and not to the general public information process, for which the Directive requires only ‘reasonable and sufficient’ timeframes.

With regard to sectoral reports, the Supreme Court concludes that neither European nor Spanish legislation requires that such reports be made available before the public information procedure is opened. Law 21/2013 of 9 December on Environmental Assessment expressly provides that both procedures must be carried out simultaneously. What matters is that public participation is genuine and effective, not that there is a rigid formal order between the stages of the procedure.

This judgment consolidates a line of case law already established by the Supreme Court’s judgments STS 1768/2023 of 21 December, STS 119/2024 of 25 January and STS 316/2025 of 21 March, and has direct implications for renewable energy developers with projects currently under consideration or already authorised:  the sharing of connection facilities, the halving of the public information period, or the simultaneous processing of public information and consultations with sectoral authorities are not, in themselves, grounds for invalidating wind farm authorisations. What is decisive, in all cases, is the functional analysis of the specific circumstances and the actual effectiveness of the environmental assessment and public participation that have taken place.

These three clarifications provide greater legal certainty for wind farm authorisation procedures and must be taken into account by both developers and public authorities when processing future projects.