Portugal faced over six hours largely disconnected from the broader European power grid on April 28, 2024, following a widespread system collapse initially originating in Spain.The incident prompted questions about cross-border energy assistance protocols and the reliability of increasing interconnection between the Iberian Peninsula and its neighbors,France and Morocco [[1]]. A parliamentary inquiry revealed a delay in support from Spain as it addressed its own grid instability, highlighting vulnerabilities in the region’s energy infrastructure as reliance on renewable sources grows [[3]].
Portugal was largely on its own for over six hours during a widespread power outage on April 28, 2024, according to the head of the country’s power grid operator. The incident, which impacted both Portugal and Spain, has raised questions about energy solidarity between the two Iberian nations.
João Conceição, administrator of REN – Redes Energéticas Nacionais, told lawmakers that Spain initially indicated it could not offer assistance while working to stabilize its own system. “They said they couldn’t give us support while they stabilized their system, but they had immediate help from France and Morocco,” Conceição stated during a parliamentary hearing convened to investigate the blackout. Support from Spain’s Red Eléctrica didn’t begin until 5:30 p.m. via the Douro International interconnection.
At the time of the system collapse, Portugal was consuming 5,800 MW of electricity and importing 2,000 MW from Spain to power pumping operations at its dams, REN data shows. Conceição maintained that the electrical interconnections with Spain “have more advantages – especially economic ones – than risks.” He noted that Portugal has benefited by €3.2 billion over the last four years through the import of competitively priced Spanish solar energy. However, he added that the high level of interconnection “dragged us into a problem” originating on the Spanish side of the border.
REN CEO Rodrigo Costa acknowledged that power outages are a possibility. “The outages can happen, and we are always subject to another outage tomorrow, there is nothing that can prevent it,” he said. “We are subject to terrorism, which is a concern for us, cybersecurity and natural disasters. The only thing we can do is be prepared to recover, which is what we did on April 28.” Costa added that REN conducts training exercises to prepare for outages, “but it is impossible to simulate 100%.”
On April 28, Conceição said, the Portuguese electrical system was functioning normally for a sunny day, with wind and solar production accounting for around 46% of the total. Including hydroelectric power, renewables contributed approximately 62% to Portugal’s energy consumption. Spain relied even more heavily on renewable sources, with a total of 92%, of which wind and solar accounted for 75%.
Portugal was also importing competitively priced solar energy from Spain on that day, Conceição emphasized. The southwestern region of Spain produces nearly 13,000 megawatts of solar power, along with almost 3,000 megawatts of wind energy, while its domestic consumption is significantly lower. “The Spanish system was producing a lot of energy there that was being sent to the other two regions of Spain and to Portugal,” he explained.
Recounting the timeline of events, the REN administrator said a loss of 2,200 megawatts of solar production was registered in that area at 11:33 a.m. “Within four seconds, we activated the emergency plans of the National Electrical System and, together with the distribution operator we gradually disconnected a total of 4,200 MW of consumption, starting with pumping. Portugal, which was an importer, became an exporter of energy, in an immediate, almost automatic attempt to help the Spanish system and try to stop the problem. It wasn’t enough, and a total collapse occurred,” he reported.
When asked if more electrical interconnections between Portugal and Spain, and also with France, could have prevented the blackout, João Conceição said it “could allow the European system to support Spain with more strength and manage to stop the total collapse in the country.” However, he cautioned that it could also mean “this problem would spread throughout Europe and, instead of an Iberian blackout, it would be a European blackout.”
Regarding the government’s decision to increase the autonomous start-up capacity of the grid from two to four plants, João Conceição said it “is a correct decision.” “Having more blackstart, however tempting it may be, could be counterproductive in the sense that we quickly have many islands, but then when we try to synchronize them, the system collapses completely.”
The REN administrator concluded by saying “it is incorrect to conclude that the blackout was caused by renewable energies.” However, he admitted that “gas plants may play an important role in mitigating the volatility of renewable energies, which also benefit from greater storage capacity.” “The cause of the blackout was a problem with voltage control in Spain,” he emphasized.
The administrator revealed to lawmakers that the first phone call he made after the blackout “was to the SIS, to rule out any cyberattack issue.” Rodrigo Costa spoke with the first government member – the Secretary of State for Energy, Jean Barroca – at 11:44 a.m., 11 minutes after the blackout.
In June 2024, the Environment Committee of the Assembly of the Republic unanimously approved the creation of a working group to determine the facts, understand the circumstances and causes of the blackout, and identify lessons to be learned from the event in order to strengthen security, resilience, and public confidence in these essential services.
