The cause behind the blackout that left the Iberian Peninsula without electricity for several hours, considered an exceptional event, is still unknown. Although there are several investigations underway, it has opened the debate on the resilience of the electricity system.
The European Network of Electricity Transmission System Managers (ENTSO-E) announced the creation of a committee to investigate the causes of the 28th of April blackout, which it classified as “exceptional and serious.”
This panel of experts will have to prepare a factual report that will form the basis of the final report by the deadline of the 28th of October this year. The final report on the investigation should be published by the 30th of September 2026 at the latest.
There are several open possibilities. It is known that the generalised electricity cut originated in Spain, with Red Eléctrica, the company that manages the energy networks in the neighboring country, pointing out as the main cause of the blackout a sudden loss of solar energy generation for 20 seconds, at around 11:30, which had a domino effect and brought down the entire interconnected Iberian electricity system.
In Portugal, the investigation is in the hands of its counterpart, REN – Redes Energéticas Nacionais, which requested the postponement of the delivery of the report, which was due on the 18th of May, with the Energy Services Regulatory Authority (ERSE) extending the deadline by 10 days.
According to the regulator, the request was intended to allow the manager of the national networks to collect information that he had not yet had access to.
But the ongoing investigations are not limited to energy sector regulators.
On the 1st of May, the Ministry of Infrastructure and Housing determined that the National Civil Aviation Authority (ANAC), the National Communications Authority (Anacom), and the Institute of Mobility and Transport (IMT) would carry out audits of the electrical blackout. If the entities have not requested an extension of the deadline, the conclusions will have to be delivered by the 28th of May.
Meanwhile, REN is gradually resuming energy import limits from Spain, after having chosen to cut energy purchases from the neighbouring country after 28 April.
According to REN’s most recent decision, until the 2nd of June “the interconnection capacity between Portugal and Spain will be limited, in the importing sense, to 2,000 MW in the periods between 09:00 and 10:00 and between 19:00 and 20:00.” In the remaining interval – between 10:00 and 19:00 – there will be a limit of 2,500 MW.
The electricity network manager has been reviewing the energy import measures every week as part of the ongoing stabilisation process of the Iberian electricity market (Mibel).
The blackout showed the importance of increasing the resilience of the European Union’s energy grid, at a time when the Iberian Peninsula’s connectivity is 3% below the rest of the EU.
The Portuguese Government has been advocating an increase in Portugal’s energy interconnection with the rest of the EU to 15% by 2030, through the construction of more interconnections, namely in the Pyrenees that connect Spain to France.
Last week, the Minister of Environment and Energy, Maria da Graça Carvalho, went to Brussels to deliver a letter asking for a “firm political and financial commitment” to move forward with interconnections between the Iberian Peninsula and the rest of the EU. A topic that has been discussed frequently, and which would increase energy security, reduce dependence on fossil fuels, lower costs, and facilitate the transition to renewable energy.
Meanwhile, the Government also announced that it wants to insert the Baixo Sabor and Alqueva plants in the role of ‘black start,’ that is, the autonomous start of the electricity system, to accelerate the restoration of energy, in case another blackout like the one on the 28th of April occurs again.
Samantha Gannon
info at madeira-weekly.com
