Europe recently experienced its most extensive power outage in over two decades on the Iberian Peninsula, significantly affecting parts of Spain, Portugal and France. This disruption caused major challenges for the local population and raised a common concern among governments across the continent: could such an event happen elsewhere? The incident once again drew attention to the vulnerabilities of Europe’s electricity transmission systems and emphasized the importance of grid resilience. Many countries, including Türkiye, operate in coordination with the European energy grid through their connection to the European Network of Transmission System Operators for Electricity (ENTSO-E). This recent outage clearly demonstrates the need for Türkiye and other interconnected countries to continuously strengthen their energy infrastructure and maintain a high level of preparedness to reduce the risks of regional failures.
While investigations continue and expert reports are still being prepared, the root cause of the outage has yet to be determined. Therefore, current assessments rely on existing hypotheses. In recent years, Europe’s energy system, including that of the United Kingdom, has become increasingly interconnected. This integration generally offers benefits, especially in balancing supply and demand during the decarbonization process. However, interconnection also entails risks.
Managing a highly integrated system becomes much more complex due to its scale, the number of components involved, and the frequency of unexpected events across regions. In such systems, failures in one part of the grid can trigger cascading effects. Although interconnection provides significant advantages, such as cost efficiency through shared reserves and secure access to electricity across borders, it also allows local failures to impact broader regions. One of the most serious risks is the possibility of a chain reaction where the failure of one transmission line causes others to overload, resulting in a domino effect of outages. To prevent such scenarios, grid operators apply the N-1 security criterion, which requires that the system must remain stable even if a single component, such as a transmission line or a power plant, goes offline. Although overall interconnection improves Europe’s energy reliability, the recent crisis in Spain and Portugal serves as a critical case study. The rapid spread of the blackout across the Iberian Peninsula highlights the need for in-depth analysis, which may take days, weeks or even months.
What went wrong?
Red Eléctrica de España (REE), the national authority responsible for Spain’s high-voltage transmission network, oversees over 44,000 kilometers (27,340 miles) of transmission lines and more than 6,000 substations. REE is responsible for balancing supply and demand in real time, integrating renewable energy into the grid, continuously monitoring production, and managing Spain’s electricity interconnections with other countries. During the large-scale blackout on April 28, 2025, which affected both Spain and Portugal, REE reported that the incident was caused by the simultaneous shutdown of two critical generation units in the Extremadura region. This event led to a sharp drop in electricity demand from 27,000 MW to below 13,000 MW. In response, Prime Minister Pedro Sánchez announced the establishment of an investigative commission to determine the causes of the incident and evaluate the role of private energy companies. Following the event, REE was widely criticized, particularly for its grid management shortcomings in preventive planning and inadequate capacity to accommodate renewable energy.
The sudden disconnection of two major generation units reportedly destabilized the grid, severed the interconnection with France and led to a system-wide collapse. Critics argued that REE lacked sufficient early warning systems and failed to implement effective preventive measures. Furthermore, some experts noted that REE had not provided adequate infrastructure to accommodate the increasing share of solar and wind power. This deficiency, especially during periods of low demand, created serious imbalances. Several experts and members of the public claimed that REE had been slow to modernize Spain’s transmission network and that the infrastructure remained outdated. In its official statements, REE attributed the blackout to the abrupt shutdown of two key generation units in southwestern Spain, followed by the activation of automatic protection systems. The company emphasized that the overall transmission system was structurally sound and reported that 95% of operations were restored within hours. It also announced new investments in cooperation with the European Union to strengthen the resilience of the grid.
The criticism directed at REE revealed broader structural and governance challenges associated with Spain’s energy transition. Beyond REE’s shortcomings, regulatory gaps, public-private coordination failures and compatibility issues in integrating renewable energy sources into the grid all contributed to the severity of the crisis. Although REE technically succeeded in restoring power, its lack of effective preventive management and public communication increased concerns about institutional preparedness.
To date, no evidence has been found linking the outage to a cyberattack, human error or extreme weather. Nevertheless, the blackout had serious consequences. Electricity demand plummeted, trains were halted, hospitals switched to backup generators, credit card systems failed and many people were trapped in elevators. Citizens relied on radio broadcasts for updates and rushed to find flashlights, candles and lighters. In major cities like Madrid, people had to walk home due to the disruption of public transportation. Although the blackout occurred in the westernmost part of Europe, such large-scale regional incidents present potential risks for other countries connected to the ENTSO-E network.
Türkiye, located at the eastern end of the system, was not directly affected by this event. However, the incident illustrates how deeply interconnected Europe’s energy infrastructure has become and how local failures can cross borders. In this context, the resilience and flexibility of Türkiye’s energy infrastructure are of critical importance. The April 28 blackout reaffirmed the vulnerabilities of interconnected transmission systems and the necessity of long-term investment. While Türkiye benefits from its integration into the European grid via ENTSO-E, it must also prioritize modernizing its transmission infrastructure, integrating renewable energy sources and developing energy storage technologies to strengthen national energy security.