What caused the recent power outage in Spain, Portugal, and Southern France?
On 28 April 2025, at precisely 12:33 CEST, a significant power disruption unfolded across the Iberian Peninsula, momentarily severing Spain and Portugal from the broader Continental European power grid and causing widespread outages, including parts of southern France. This event, the most severe of its kind to date, has sparked critical conversations about the stability of Europe’s interconnected power system.
What Happened? In technical terms, the blackout was triggered by two poorly damped inter-area oscillations between the Iberian and Central European grids. During the second oscillation, the Spanish power subsystem lagged by over 90 degrees relative to Central Europe. This phase misalignment activated protective relays, which quickly tripped the crucial 400 kV France–Spain interconnector, isolating the Iberian grid and resulting in a rapid, widespread power collapse.
Key Facts:
Cause: Low-frequency ‘inter-area oscillations’ followed by the fault-induced disconnection of the 400 kV France–Spain link.
Impact: Roughly 15 GW of load lost in under five seconds, causing widespread outages in Spain and Portugal and brief interruptions in southern France.
Historical Context:
- December 2016 – Minor oscillation event causing brief separation (no major blackout).
- 24 July 2021 – 400 kV line fault leading to partial grid separation and power cuts.
- 28 April 2025 – The most severe to date, with over half the Iberian Peninsula’s load dropping in seconds.
Could This Have Been Prevented?
One critical question is whether embedded, distributed energy storage could have mitigated, or even prevented, this kind of large-scale disruption. The short answer is yes, and here’s why:
Synthetic Inertia & Fast Frequency Response:
What Happened: The system experienced undamped, low-frequency oscillations.
How Storage Helps: Advanced energy storage systems, including battery and compressed air technologies, can inject power within milliseconds, providing synthetic inertia and dampening these oscillations before they trigger protective trips.
Local Balancing & Reduced Stress on Interconnectors:
What Happened: A fault on the France–Spain interconnector caused sudden load shifts, overloading nearby systems.
How Storage Helps: Distributed storage can balance power locally, reducing the scale of swings that must be absorbed by distant interconnectors, lowering the risk of system-wide separation.
Islanding Capability:
What Happened: Once the interconnectors tripped, large portions of the grid collapsed.
How Storage Helps: Distributed storage could allow affected regions to form stable, temporary “islands,” maintaining local power supply until systems can be re-synchronized.
Emergency Reserves:
What Happened: The event exceeded the available automatic reserves, resulting in mass load shedding.
How Storage Helps: Embedded storage can act as a rapid-response reserve, delivering contingency support much faster than conventional spinning generators.
In Summary
While storage alone cannot eliminate the need for robust interconnectors and coordinated grid management, it can dramatically enhance resilience, allowing grids to absorb shocks, dampen oscillations, and maintain local stability during faults. For regions like Iberia, where renewable energy penetration is high and inertia is low, such measures may prove essential to preventing future blackouts.
As Europe accelerates its energy transition, building this resilience into the grid will be critical. Strategic investments in distributed storage, grid modernization, and smarter, faster grid control systems will be key to ensuring a stable, low-carbon energy future.