The International Energy Agency (IEA) believes that the April 28 power outage in the Iberian Peninsula shows that electricity safety does not only depend on the quality of the network’s operation, but also on the quality of network operations and the behavior of all connected assets, as the accident was caused by “rapidly successive technical failures”, including the incorrect disconnection of a generator, even though the voltage level had not yet exceeded the set threshold.
“This event was caused by a rapid succession of technical failures,” the agency said in an appendix to its World Energy Outlook 2025 report, which includes the conclusions of ENTSO-E, the European Network of Transmission System Operators, noting that abnormal fluctuations in voltage and power flow destabilized the power system minutes before the outage.
“This instability was followed by a sharp rise in voltage, as the protection system accidentally disconnected the generator that was absorbing reactive power, even though the voltage level had not yet exceeded the threshold established by the regulations,” the IEA highlighted, according to the European Press Agency.
Therefore, voltages rose further as more plants went offline, creating a “cascade of additional disconnections,” while hundreds of megawatts (MW) of small distributed generation unexpectedly went offline, making it even more difficult for system operators to respond.
For the IEA, the April 28 power outage “demonstrates that electrical security in modern systems depends not only on power generation, but also on the quality of grid operation and the behavior of all connected assets,” highlighting the need for binding standards that require all generators to support the system in an emergency and only disconnect “if clearly defined thresholds are exceeded.”
In this sense, he continues to believe that preparedness is essential, stressing that the rapid restoration of electricity supply in the Iberian Peninsula was possible thanks to strong interconnections with neighboring countries, strong emergency protocols and available black-start capacities, and therefore points out that “maintaining and strengthening these capacities is important”.
Similarly, it said the international attention drawn by the Iberian power outage provides an opportunity to review some common elements of power supply security and resilience as energy systems evolve.
Although power systems and market structures vary from country to country, the IEA has identified four fundamental pillars that are needed in all cases, with a strong network infrastructure, including strong networks and regional interconnections, as the basis for safe operation.
Second, the IEA believes that power system flexibility is essential to balancing supply and demand. This includes demand response, storage and maintenance of available generation, and measures to ensure that the market properly values these services.
Additionally, technical solutions such as batteries with synchronous capacitors and grid-forming inverters are required to support system stability as the power generation matrix evolves.
Finally, he believes it is important to adapt operational frameworks as the power system transforms, updating grid codes, reserve requirements, balancing mechanisms and regulatory structures to respond to new challenges and technologies.
“The economic costs of power outages are very high,” the IEA summed up, adding that examples such as those in Chile in February this year and on the Iberian Peninsula in April “remind us of how power outages can have a domino effect, affecting millions of people.” As electricity accounts for an increasing share of final consumption and power systems become more complex, “the security of electricity supply becomes increasingly important.”
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