International Energy Agency assigns blame for Spain's nationwide power blackout to power companies' errors

The causes of April 2025's major power outage across Spain remain unresolved. Nearly a dozen reports from different organisations and companies have been compiled, analysing the reasons that led to the worst power outage in recent Spanish history on 28 April. This time, it is the International Energy Agency (IEA) that, in its latest study, asserts that the blackout across the Iberian Peninsula demonstrates that electricity security depends not only on generation, but also on the quality of grid operation and how all connected assets then behave. This because the incident was triggered by "a rapid succession of technical failures", including the erroneous disconnection of generators, even though voltage levels had not yet exceeded established thresholds.

The "sequence of technical failures" that occurred on 28 April is the cause cited by most reports and the IEA report also seems to concur with this viewpoint. In its document 'World Energy Outlook 2025', the IEA also includes the conclusions of European power grid experts (Entso-E), which stated that, in the minutes leading up to the blackout, the electricity supply system "became unstable, with unusual fluctuations in voltage and power flow".

The agency, headed by Fatih Birol and affiliated with the OECD (Organisation for Economic Co-operation and Development), includes a specific chapter on the outage in its report, published on Wednesday. The power outage affected over 50 million people in Spain, Portugal and southern France, the worst event of its kind in Europe in decades, according to this IEA document.

The system "instability" referred to in the report was followed by a "sharp voltage spike" that caused protection systems to trip and then disconnect, but this happened "erroneously", as these voltage levels "had not yet exceeded regulatory thresholds", the IEA notes. Thus, as more power plants went offline, the voltage increased even further, leading to "a cascade of additional shutdowns", while hundreds of megawatts (MW) of smaller distributed sources unexpectedly went offline, further complicating the system operators' response.

Furthermore, the agency calls for a "review" of certain common elements of electricity supply security and resilience, while urging the application of "lessons learned" from the historic incident. In this regard, the report warns that a "robust grid infrastructure, including strong networks and regional interconnections, is essential as it forms the backbone for safe operation".

At the same time it recommends greater "flexibility of the electricity system" to balance supply and demand. It also calls for new technical solutions such as synchronous condensers or batteries equipped with grid-forming inverters and considers it crucial to "adapt operating frameworks" as electricity systems are transformed.