Lisbon, May 29, 2025 (Lusa) - The executive director of Portugal's grid operator REN, João Conceição, said on Thursday that there is no doubt that the whole sector has done its homework well, with regard to last month's near-total outage in the system, but he stressed that the data shows that the blackout that originated in Spain was impossible to stop at the border.

A month after the incident that cut off the electricity supply in Portugal and Spain, Conceição stated that there is already more information available than has been made public. However, he said that "it wouldn't be right" to share it at this moment, given that there are several investigations underway.

Conceição was speaking at the seminar titled ‘Security of Supply in Portugal’ that was held in Lisbon as part of World Energy Day, which was being marked on Thursday.

However, he said that there is one fact that he can already confirm about the blackout: "It originated in Spain."

He also provided more technical details to support the fact that the disconnection systems - interrupting the supply of some consumption to avoid overloading the system - in fact worked. 

"The scale of the problem is that it was so violent that there are no possible mitigating measures to stop it at the border," he said, adding that this was why "the blackout occurred."

But looking back, he said, he has no doubt that REN did its homework, and it was not the only actor to have done so. 

"The whole sector did," he emphasised.

On Wednesday 28 May, REN (Redes Energéticas Nacionais) and the distribution company E-Redes submitted their report on the 28 April electricity blackout to the sector regulator, ERSE, with both of them asking for it to be considered an "exceptional event."

Such a classification could be decisive where the payment of compensation is concerned: if it is considered to be exceptional, the obligation to compensate consumers could be reduced or even ruled out.

During the seminar, Conceição also pointed out that the sector "has complexified in a very significant way and has become much more democratic" than previously. 

"Today everyone can be a consumer and producer of energy, which means that we are at a crucial stage in the energy transition," he said, adding that there is a need to continue along this path to ensure “that there are no new blackouts.” 

To complement the need to strengthen grid security, he explained, it is also "essential to develop storage solutions not only in technical terms, but also in economic and market terms." 

For his part, the head of the Directorate General for Energy and Geology (DGEG), Paulo Carmona, commented that the recent blackout "served as a very important test for the resilience of the electricity system" in Portugal and to see if "black starts" worked.

Following the blackout, power stations with the capacity to make an autonomous start-up - known as a 'black start' - were activated, namey the Castelo de Bode hydro-electric plant and the Tapada do Outeiro gas-fired plant. ERSE has already ordered REN to contract two more plants with this capacity - namely the hydro plants Baixo Sabor and Alqueva - and these are due to come into operation on 1 January 2026.

"It was a check-up to prepare for a really bad event like sabotage," added the DGEG chief.

Finally, the chairman of the board of directors of E-Redes, José Ferrari Careto, emphasised that the time it took to restore power "was very good by international standards."

Ferrari Careto also said that on the day of the blackout, E-Redes had 600 people on the ground in case it was needed. 

The blackout caused significant interruptions to the electricity supply in Portugal, Spain and parts of France. Preliminary investigations point to a sudden loss of solar power generation as a possible cause, but definitive conclusions are still pending.

The European Network of Transmission System Managers (ENTSO-E) is investigating the causes of this blackout, which it has classified as exceptional and serious, and has set up a panel of experts for the purpose. This panel has been charged with drawing up a factual report that will serve as the basis for the final report, to be completed by 28 October this year. 

SCR/ARO // ARO.

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