Two days of shock  in Spain as power system experiences a national blackout

Key Takeaways

• Electrical power in Spain was interrupted for 10 hours
• At least 30 people died due to indirect effects
• No clear cause yet but many possible solutions
• ENTSO-e will establish an export panel to investigate and publish a report on the event

Timeline

On 28^th April, at 12:30pm local time a major power cut occurred across mainland Spain. About three hours before the outage, power quality sensors in homes in the Madrid area showed warning signs of an unstable grid – there were small fluctuations in voltage around 9:30am local time. Later the frequency of electricity dropped below the usual 50 hertz. The voltage measured went up and down by about 15 volts every 1.5 seconds. The automatic monitoring system noted a sharp drop at 12:35pm local time before readings stopped being reliable. Most of the drop in power happened in 5 seconds with 15GW being lost. The interconnection with France automatically tripped to prevent further damage in the form of a massive contagion in the rest of Europe. Around 15 gigawatts (GW) of electricity generation, nearly 60% of energy in use at the time, was lost.

The city of Madrid activated its emergency plan (PEMAM). Police were brought in to control the local traffic and keep the streets secure during the disruption. Later in the day power was returned to the airport with a 20% reduced capacity, but the long and medium distance train services did not resume until the next day. The Spanish Prime Minister Pedro Sanchez convened an emergency meeting of the National Security Council.

Around 4pm local time the Spanish electrical operator (REE) estimated it would take between 6-10 hours to restore normal service. The regions of Aragon-Cataluna and Galicai-Leon were the first to be reconnected. To alleviate the power cut, Morocco and France sent electricity through international power lines. Morocco delivered 900 MW through the interconnect that crosses the Strait of Gibraltar while France sent 2 GW through power lines supplying Catalonia and the Basque Country.

By 7am local time on the 29^th of April electricity had been restored to 99% of energy demand and full restoration was achieved by 11:00am local time. However, on the same day some institutions like the Ministry of Defence and the Navy headquarters were still suffering from power outages. During the morning, REE attributed the outage to a disconnection of the grid in the south-west of Spain, while ruling out a cyberattack. REE also announced it would be investigating the cause of the disconnection. At 6pm local time Pedro Sanchez held a press conference saying that no hypothesis could be ruled adding that the government did not yet know the cause of the blackout.

Effects

Several deaths occurred indirectly because of the outage. In Catalonia, 25 people were harmed by malfunctioning generators or misuse of them. In Madrid, at a Carabanchel neighbourhood, a woman died in a fire caused by a candle. The fire trapped several people in a building. Several people were also harmed as a result. In Alzira, Valencia, a 46-year-old woman who depended on an oxygen machine died. In Taboadela, Ourense, a couple and their son died of carbon monoxide inhalation due to a generator being used indoors. One of the people in the couple required a mechanical ventilator, which prompted the use of the generator.

As a result of the power outage many pieces of infrastructure had to be shut down. Spanish train operator Renfe confirmed all trains had stopped and 35,000 stranded passengers had been rescued. Spain’s Guardia Civil police force said it had rescued 13,000 passengers trapped on trains by itself. Madrid’s Barajas International Airport was left without power. The country’s nuclear power plants were automatically taken offline, and backup generators were used to supply cooling to keep the reactors safe. Hospitals were able to stay mostly functional by activating their backup generators.

All the democratic buildings included the Palacio de la Moncola (residency of the Spanish Prime Minister) were without power and both the Congress of Deputies and Senate suspended parliamentary activity for the 29^th of April.

Additionally, there was a major impact on the Spanish economy and national productivity, Spanish network traffic on fell to 17% of normal usage. The employers’ organisation CEOE estimated that the outage resulted in 1.6 billion euros of economic losses.

Possible causes

The causes of the power outage are currently under investigation. The purported reason was two fluctuations in the electrical grid, the second of which caused Spain’s power system to disconnect from the European grid. This has been linked by REE to an incident at two photovoltaic plants in the southwest of Spain. However, other experts have said this incident is unlikely to be the cause of the collapse of the whole system as there was many synchronous sources of electricity at the time of the outage including nuclear, hydropower and even coal.

The power outage did prompt discussion about the stability of an electricity system with a high proportion of renewable energy. However, REE and other experts argue it was unlikely to be the fault of renewable sources. Also, the benefits of cheaper and cleaner energy are difficult to ignore making it unlikely for a change in system to be adopted.

However, the outage has highlighted the need for continual investment in power gird stability and resilience when using higher shares of renewable energy. Firstly, there was surprise amongst some industry experts at the inability to isolate the blackout to a specific area thus requiring the system to be re-energised from scratch. Additionally, it has shown the fact that Spain is an “energy island” with interconnections with the rest of the continent being far lower than the European commission demands. This has been blamed on French resistance because of this desire to protect its nuclear sector from competition including Spanish solar power. A future report from Brussels could put pressure on France to change its ways. Furthermore, it was shown the weakness in Spain’s delay to the mass deployment of batteries unlike in Germany, Australia and California. Storage of electricity through batteries or pumped hydroelectric would have likely helped the mitigate the blackout.

Spain’s National Cybersecurity Institute is investigating the possibility of a cyberattack as the cause of the incident along with the Joint Cyber Command under the Ministry of Defence. However, several government officials have ruled it out. A thorough forensic analysis is estimated to take 1-3 weeks. So far there have been no indications in Spain of an attack, the only successful  ones on a national scale took place in Ukraine in 2015 and 2016 by Russia. The National Cybersecurity Institute did warn in 2024 about a significant increase in cyberattacks affecting industrial environments and critical systems.” The institution cited the malicious software BlackEnergy as an example, which was used by Russian hackers on December 23, 2015, to sabotage the electricity distributors in the Ukrainian region of Ivano-Frankivsk, causing a blackout that affected 1.5 million people.

The Audienica Nacional (central criminal court) judge has initiated a preliminary investigation to determine whether the outage was an act of sabotage against critical Spanish infrastructure. If it was sabotage it would fit within the parameters of a terrorist crime.