Blackout. ERSE advocates strengthening mechanisms

The president of the Energy Services Regulatory Authority (ERSE) argues that the blackout of April 28 highlighted the need to reinforce the resilience of the Iberian electricity system, with concrete measures to prevent, mitigate and respond to large-scale failures.

In written statements to Lusa, within the scope of World Energy Day, Pedro Verdelho stressed that incidents of this nature require rigorous identification of the causes and the adoption of technical and organizational solutions to avoid future repetitions.

According to the information available, the collapse was caused in southern Spain, where a sudden power outage caused an imbalance between supply and demand. Automatic reserve and load shedding mechanisms — which switch off part of the consumption to avoid collapses — proved insufficient to stop the chain failure.

“It is important to determine the causes that led to this massive collapse, but the ENTSO-E [European Network of Electricity Transmission Operators] report will certainly do so,” he said, noting that the first document must be presented within six months.

When asked about the possibility of a similar event happening again, Pedro Verdelho explained that electrical systems are prepared to withstand various extreme events. However, when several unlikely failures occur simultaneously, it becomes “almost impossible to avoid a power outage”. He also noted that a blackout of this magnitude had not occurred in over 40 years.

Following the incident, power plants with autonomous start-up capacity ('blackstart') were activated – Castelo de Bode and Tapada do Outeiro. And as the official pointed out, ERSE has already ordered REN to contract two more power plants with this capacity – Baixo Sabor and Alqueva – which should come into operation from January 1, 2026.

Regarding the lessons to be learned one month after the blackout, he emphasizes that the ongoing investigation will allow “to identify fundamental elements for the concrete measures to be adopted”. But he stresses that “the strong impacts of these incidents on society require the identification of the cause of the problem and the implementation of improvements in the mechanisms for prevention, mitigation, restoration of service and communication in crisis situations”.

Recalling that the energy transition and the increasing penetration of renewables introduce new challenges, namely the reduction of system inertia, which accentuates frequency variations and requires faster power control, the president of ERSE argues that to mitigate these effects the system should maintain synchronous generators, modernize inverter power regulators and incorporate solutions such as batteries with advanced control.

“All these solutions are available and can be used alongside greater digitalization of the network in a cost-effective way to ensure a resilient network, adapted to an increasingly decarbonized energy system,” said the entity’s president.

ERSE also argues that resilience must start at the local level. Critical infrastructures such as hospitals, water systems, communications and elevators must be equipped with alternative power supplies to ensure operation in emergency situations.

Regarding investment in the distribution network, the regulator considers E-Redes' proposal in the Electricity Distribution Network Development and Investment Plan (PDIRD-E) for the period 2026-2030, in the amount of 1.6 billion euros, to be adequate. "Without prejudice to this position, ERSE identified some aspects in which the proposal could be improved, in order to make clearer the adoption of some innovative technological options and practices in terms of planning and active management of the network, and which have been demonstrating maturity for this", it commented. The final version of the proposal now awaits approval by the State, as grantor.