The analysis committee of the total blackout on April 28 identified a third event that affected the system 19 seconds before the other two incidents. This event initially destabilized the system and ultimately led to a loss of at least 15 GW of generation and the reaching of “national ground zero.” While the two later incidents, which occurred after 12 hours, 33 minutes, and 16 seconds, took place at facilities in the southwest of the peninsula, the event occurred 19 seconds earlier in the “south” of Spain.
In an interview with TVE, Third Vice President and Minister for Ecological Transition, Sara Aagesen, described this new event that destabilized the power grid as a “novelty” in the investigation into the causes of the major blackout. She explained that a preceding event had to be added to the two system oscillations that occurred three seconds apart and led to the collapse in a total of five seconds. However, for this first event, as with the other two, she was unable to specify the exact location or type of installation, nor explain why the system failed to isolate it.
“Experts know that there was a generation outage in southern Spain 19 seconds earlier. We are determining how much power was affected, what type of installation it was, and why this happened,” Aagesen said.
Considering all the unknowns that still need to be clarified, the sequence of events leading up to the major blackout can be summarized as follows: The system transitioned from operating “with complete normality” at 12 hours, 33 minutes, and 16 seconds on April 28 to a first generation loss 19 seconds before the outage, followed by a “second event” five seconds earlier that stabilized but could not be restored, and a third event that ultimately led to “National Zero.”
South and Southwest: Suspected Photovoltaics
This third incident complements the two previously reported incidents in the southwest of the peninsula, which are suspected of having been caused by photovoltaic installations, which are numerous in the region. The same applies to the first chronological incident mentioned by Aagesen, which also occurred in southern Spain. Nevertheless, the third vice president emphasized the need to defend renewable energies, which made a significant contribution to the energy mix last Monday, despite repeated warnings—including from Red Eléctrica and the CNMC—about the risks that a massive penetration of renewable energies could pose to the electricity system. However, Aagesen rejected the claim that the government knew a power outage like the one on April 28 was imminent. “We were never warned that something like this could happen. Of course not,” she explained.
“Renewable energies are fed into the system in perfect condition,” Aagesen emphasized, outlining the framework by which Red Eléctrica ensures that there are backup elements for the electricity fed into the system on a given day. This occurs in accordance with the previous day’s demand calculation, when the expected supply is “matched” with demand. The configuration of the energy mix determines the type of generation and the price, which is handled by the OMIE. “The electricity grid decides, based on the generation and consumption situation, whether an additional or backup mechanism is needed,” Aagesen added, noting that the system has been operating “under conditions of increased security” since April 28.
Currently, some experts believe that due to the large number of renewable energies last Monday, few technologies were able to provide the necessary support. According to the Ministry for Ecological Transition, up to 15 GW was available on the day of the major blackout to offset a drop in generation – more than 5 GW from the interconnection with France and another 10 GW from other technologies – but this was not enough to prevent “national zero.”
On-site visits and data requests
A week later, the committee to analyze the causes of the blackout, chaired by Aagesen, which is now divided into two subgroups dealing with the operation of the electricity system and cybersecurity, as the government continues to keep the “hypothesis” of a cyberattack open, has not yet found any causes and is continuing to analyze data on rare earth metals and information from electricity companies – both generators and distributors. In this context, the committee is requesting new data.
According to AagesThey need to analyze “750 million data points” and request “4,000 oscillographic data sets” corresponding to the power generation plants in the south and southwest of Spain, where the three events prior to the blackout were detected. They have also asked the companies for information on all power plants with a capacity of more than 1,000 megawatts and plan to visit the operators’ more than 30 control centers, with the exception of the two power plants in Red Eléctrica.
When asked when a cause for the blackout might be found, Aagesen expressed caution, although it is “complicated in this context.” “There is a lot of interest in finding out, but we will provide rigorous information,” she added. Regarding Sumar and Podemos’s demands to increase public control over the electricity system and even nationalize Red Eléctrica, Aagesen considered this a “completely legitimate debate,” but doubted that Red Eléctrica would function otherwise. “At the moment, from a technical point of view, it’s in exceptional hands. I don’t think it would be any different if the system operator were in public hands,” she said, emphasizing that the priority now, in any case, is to find the cause of the blackout.
Separating the Nuclear Debate and Analyzing the Owners’ Request
The blackout has given impetus to the defense of nuclear energy as a stable source of electricity, in a context in which the shutdown of the first reactor—one of two in Almaraz—in November 2027 is fast approaching. This is in line with the decommissioning plan agreed upon by the state-run radioactive waste management company (Enresa) and the plant owners in 2019, which they now want to amend to extend the plants’ operation.
Regarding this nuclear debate, Aagesen clarified that the power outage occurred before the closure schedule came into effect and reiterated that her ministry currently has no concrete proposal from the electricity companies. However, she again refused to pass on to citizens the costs that the companies no longer want to bear, such as the Enresa tax for dismantling power plants and disposing of nuclear waste.
“The shutdown of the nuclear power plant is planned for the years 2025 to 2027, and this event occurred in 2025, when no nuclear power plant is on that calendar,” Aagesen emphasized, calling for “isolation of the two discussions.” “The companies have been saying for some time that they are exploring the possibility of extending the calendar, but they have not submitted anything on this matter, and Monday’s event is not included in this closure plan.”
Almaraz’s owners – Iberdrola, Endesa, and Naturgy – had scheduled a meeting for May 20 to discuss the potential extension request, although Aagesen stated on Monday that this meeting “has been postponed.” In any case, she is waiting for “the proposal they send us,” but stressed that the solution will not be for citizens to pay or for the government to provide state aid to electricity companies to keep the nuclear power plants running.
“When we talk about red lines, we must keep the public interest in mind. We will not ask consumers to pay for waste disposal or state aid, or be penalized for the continued existence of [nuclear] generation in order to maximize the profits of these companies,” Aagesen explained, stressing the need to analyze the electricity companies’ proposals “rigorously,” and that the Nuclear Safety Council “will also have something to say.”
