Spain’s energy minister identified three substations in Granada, Badajoz, and Seville as the epicentre of April’s catastrophic power outage, which left the Iberian Peninsula paralysed for hours.
The failure at Granada’s substation triggered a 2.2 GW power loss, sparking cascading grid disconnections across Spain and Portugal, though the root cause remains elusive.
Minister for Ecological Transition Sara Aagesen confirmed the “extremely complex” nature of the inquiry, with analysts sifting through “millions of data points” to unravel the sequence of events. Initial hypotheses, including grid capacity shortages or cyberattacks, have been ruled out.
The investigation is scrutinising voltage irregularities in the days preceding the blackout, with excess voltage flagged as a potential catalyst for the generation collapse.
Key to the probe are two frequency oscillations detected 30 minutes before the outage, aligning with ENTSO-E reports of instability in Europe’s synchronous grid. These fluctuations, recorded in the Aragón-Catalonia electricity corridor—a critical link to France—preceded the Iberian grid’s isolation from Europe, exacerbating the frequency plunge to 0 MW nationwide.
Renewables and grid inertia
The blackout reignited debates over Spain’s energy transition, particularly its reliance on renewables and plans to phase out nuclear power by 2035. Critics argue that low grid inertia—a stabilising force traditionally provided by fossil fuel or nuclear plants—left the system vulnerable.
With renewables contributing no inertia, the Iberian grid’s frequency plummeted uncontrollably after the initial shock, triggering widespread disconnections.
Spanish Prime Minister Pedro Sánchez and Aagesen have vehemently rejected claims that renewables caused the outage, labelling such assertions “lies”. However, Spain’s competition authority had warned in 2023 of overvoltage risks linked to renewable integration, urging “urgent measures” to avert blackouts, a report opposition lawmakers claim was ignored.
The incident underscores the challenges of balancing decarbonisation with grid reliability. While Aagesen defended Spain’s renewables-driven model as “reducing external risks,” experts warn that low-inertia systems require costly stabilisation technologies, such as synchronous condensers or battery storage, to prevent cascading failures.
