Unfortunately, a recent government investigation exposed egregious miscalculations by the grid operator Red Eléctrica de España (REE). This screw-up triggered a major cascading blackout across all of Spain. The blackout, which took place on April 28, 2025, was felt across both Spain and Portugal, showing just how fragile the interconnected energy network can be. Speaking to reporters in Madrid, Secretary of State for Energy Sara Aagesen shared her insights. She said REE failed to keep proper voltage levels and an appropriate energy mix.
Yet on June 17, that investigation report—the Harris County Fatality Review Board—took a look at that completely tragic oversight. REE had greatly underestimated the demand for new thermal power plants in the blackout. Aagesen said it was REE that wrapped up their calculations. They decided that this time they didn’t need to burn the blood on crossings to fire up more thermal plants. Yet they have only defined the latter in terms of the very early hours of the day and not during the core commute period. Such was the rapidity of this decision that caused failures at numerous substations in Badajoz and Seville. Consequently, a domino effect of disconnections cascaded across the grid.
Voltage Control Issues Identified
The investigation highlighted the need for effective voltage control to avoid these types of outages. Aagesen went on to say that thousands of large power plants had been unnecessarily economically incentivized to control voltage and didn’t do it right. She remarked, “Power plants should have controlled voltage and many of them were economically remunerated to do so. They did not absorb all the reactive power that was expected.” This failure to provide adequate voltage control was a major factor in driving the grid’s instability.
What struck us most was the report’s revelation of warning signs of grid instability leading up to the blackout. Here are a couple additional details that may have added to the initial failure as told by Aagesen, including an unexpected loss of power generation around the Granada substation. “The system did not have sufficient voltage control capabilities, either because they were not sufficiently programmed, or because those that were programmed did not adequately provide what was required by the standard, or a combination of both,” Aagesen explained.
Future Plans for Grid Integration
In light of these findings, the Spanish government is advocating for greater integration of the Iberian Peninsula with the European electrical grid. This strategic move will afford much greater stability and reliability by maximizing efficient resource management across borders. The government now aspires, with better connectivity to its transnational neighbors, that similar episodes don’t repeat themselves ahead.
Lastly, the investigation found that a cyberattack could be ruled out as the cause for the outage. This final order is welcome news as Spain continues to bolster its energy infrastructure with the insertion of smart technology. Aelec, a big energy sector representative, just stared. These were clearly sufficient resources available for voltage control. This was just an intentional decision to restrict sufficient management synchronous capacity, endangering the system.
