Lights out: Why Iberia’s power cut is a warning for EU energy security

Problem

April 28th 2025 saw one of the largest electricity blackouts in European history, leaving parts of Spain and Portugal without power for almost 24 hours.

The outage exposed weaknesses in EU energy infrastructure, as the bloc gradually increases the share of clean energy in its energy mix. But in many EU countries this development is occurring within a system framework built decades ago around conventional energy sources—around 40% of the EU’s electricity grid is over 40 years old and nearing the end of its operational life.

As such, the EU’s under-invested, outdated and poorly connected electricity infrastructure cannot keep pace with the growing share of renewable energy sources. This increases the risk of serious system failures. Most importantly, however, the power cut demonstrated that the EU and its member states require a new approach to its energy security and infrastructure.

Solution

First, the EU and its member states should urgently speed up investment in the modernisation and expansion of energy grids, especially along cross-border interconnectors. Current interconnection bottlenecks make it difficult for national Transmission System Operators—as well as the European Network of Transmission System Operators for Electricity (ENTSO-e)—to respond to localised disruptions. To eliminate this, and to enable real-time energy transmission, EU member states should give priority to funding the construction of functional interconnectors.

Second, the rapid growth of renewable energy usage requires developing stabilising systems (technologies and infrastructure to maintain the balance, reliability and resilience of the electricity grid), in particular for energy storage. The EU should create a framework to support investment in storage technologies, from lithium-ion batteries to pumped storage power plants and hydrogen storage. Effective energy storage will reduce the risk of further sudden power outages.

Third, the EU should accelerate the pace of digitalisation of energy systems. Widespread introduction of smart grids, AI-based forecasting systems and smart meters will enable a faster response to different types of threats—including via cybersecurity, grid instability, climate-related extremes, and grid fragmentation or isolation.

Context

Spanish institutions, including national grid operator Red Eléctrica de España (REE), the Government Commission of Inquiry, and the National Intelligence Centre are investing the cause of the power outage; but initial analyses point to a combination of factors. The main suspect is the sudden drop in energy production in the south-west of Spain, particularly in the Extremadura region, which houses numerous solar power plants and one of Spain’s largest nuclear power plants, Almaraz.

In addition, REE and ENTSO-e have observed frequency fluctuations between the Iberian grid and the rest of Europe, which may have led to an automatic disconnection between the two. Iberia is primarily connected to the continental European electricity grid via a few interconnectors with France, which makes it vulnerable to isolation in the event of a major frequency imbalance. As a result, Spain’s national grid reported a sharp drop in generation capacity from 26 gigawatts to 12 gigawatts in mere seconds, triggering a cascade of outages and the shutdown of nuclear and coal-fired power plants.

Although renewable energy sources did not directly cause the outage, their large share of the energy mix in the absence of adequate stabilisation systems may have increased the vulnerability of the grid to disruptions.