While grid collapse is always a possibility, the scale of this outage is extraordinary. Exact technical details are still unclear, and various theories are circulating.

When production and consumption fall out of sync, a domino effect can start, he said, speaking to "Ringvaade."

"This happens too quickly for human intervention. In the Baltics, we have a frequency market that operates automatically. It adds production or electricity from cells. There's been talk about Estonia's costly reserve market. But power systems need rapidly activatable reserves to stay stable despite unexpected events. In Spain, those systems didn't respond fast enough," Liive said.

The power system balance "got lost for some reason. When frequency drops, automation kicks in, protecting plants and shutting things down. The system collapses. Half of production disappeared in five seconds."

"The Spanish system is 30 times larger than Estonia's. Of 30 gigawatts, 15 gigawatts were lost — equivalent to 15 Estonian peak consumptions vanishing in five seconds. But why it failed, we don't know yet," he said.

"We might know the technical reasons in weeks or months. A cyberattack is ruled out. There's speculation about a fire under a power line causing some lines to go down, but we don't know the exact cause," Liive added.

At the time of the blackout, solar power accounted for over 50 percent of production, with wind power also contributing.

Liive stated that while Spain has abundant renewable energy, solar and wind plants lack the inertia of traditional power plants, making the grid vulnerable during high production.

Liive noted that Estonia has multiple connections, including two cables to Finland (one offline), a link to Sweden, and a connection to Poland. Spain has fewer, with under 4000 megawatts of capacity and only three or four cables to France.

Estonia, along with Latvia and Lithuania, prepared for major outages when decoupling from the Russian and Belarusian grid in February this year.

"And it was an example of what we discussed in February when we desynchronized from the Russian system and joined the Western and Central European grid — the same one Spain and Portugal are in. Frequency must be maintained, and production and consumption must be balanced. What we prepared for happened, and many bought generators in case of a situation like this," he said. In the event, outages did not occur.

The Spanish and Portuguese power outage began at 12:33 CEST on Monday, April 28, 2025, affecting mainland Portugal, Spain, and small areas of Andorra and southwestern France.

Essential services, transportation, telecommunications, and public safety were severely disrupted in both countries, including trains stopping, airport closures, nuclear plant power losses, and over 35,000 stranded passengers. Several deaths occurred in Spain due to power cut-related issues, and panic buying was reported.

Restoration began with hydropower and international support and was mostly complete by Tuesday.

Spain alone faces €1.6 billion in economic losses due to the outages.

--

Follow ERR News on Facebook and Twitter and never miss an update!