Brazil blackout reveals ongoing risks in national power grid

The incident occurred at a reactor in the Bateias substation operated by Eletrobras, which is part of a 500-kilovolt (kV) high-voltage transmission line. The fire caused the shutdown of about 10 gigawatts (GW) of power. While some regions experienced only brief outages, others were left without electricity for over two hours.

President Luiz Inácio Lula da Silva met with Mines and Energy Minister Alexandre Silveira at the presidential palace just hours after returning from an overseas trip to discuss the incident.

The blackout activated the Regional Load Relief Scheme (ERAC), a safety protocol that automatically disconnects parts of the system to prevent broader damage. Authorities downplayed the event and rejected the notion of a systemic crisis. Mr. Silveira called it a one-off infrastructure issue, saying Brazil’s national grid operator, ONS, responded promptly.

ONS said the fire severed the connection between the southern grid and the Southeast and Central-West regions, prompting a preventive supply cut across the country in varying degrees. The Ministry of Mines and Energy classified the incident as a “severe contingency.”

In a statement, ONS said it began a coordinated response to restore power as soon as the situation was identified. Electricity was reestablished in the North, Northeast, Southeast, and Central-West regions within 90 minutes. Full restoration in the South took about two and a half hours.

ONS Director-General Marcio Rea said in the statement that the agency quickly reestablished the system, “demonstrating the robustness of the National Interconnected System (SIN).” He described the event as a controlled power interruption caused by a “fortuitous incident,” the type of failure that could happen in any country.

Eletrobras said the shutdown was triggered by a “reactor incident” and that power was restored shortly after. “ONS will determine what led to the larger disturbance in the national system. Eletrobras will collaborate in identifying the causes,” the company said.

System resilience

While experts acknowledged the system’s general robustness, the scale of the outage raised concerns. Luiz Carlos Ciocchi, former ONS director-general, said the blackout was “very different” from a 2023 incident that did not involve a fire. “The first question that needs answering is what exactly happened at the substation and why a fire in one component shut down an entire plant,” he said.

Mr. Ciocchi added that the automatic protection scheme worked as intended, but further analysis was needed. “System security must always be a top priority in the power sector,” he said. He noted that the fire happened during low consumption hours and in a region without high renewable output. “The key is understanding what went wrong.”

Power systems engineer Celso Torino pointed out that the 10GW outage was almost equivalent to power plant Itaipu’s capacity of 14 GW.

“We need to better understand why a reactor fire at a 500kV substation caused the complete shutdown of 750kV lines connecting Itaipu’s 60-hertz output to Southeast Brazil,” said Mr. Torino, a former Itaipu operations director. “The N-1 security criterion tells us this shouldn’t happen.” He referred to the N-1 standard, which requires the grid to withstand the loss of a key component without triggering cascading failures.

Mr. Torino said the episode calls for a broader governance review of the national grid, including planning, operational stability, and consumer cost structures.

Carlos Adolfo Pereira, who heads the transmission division at the Brazilian Infrastructure and Basic Industry Association (ABDIB), said it was too soon to conclude there was a substation failure and a more detailed assessment was needed.

He noted that the industry has been investing in modernizing transmission systems, especially replacing outdated equipment. “Transmission companies are expected to invest about R$40 billion through 2034 to upgrade old infrastructure,” he said.

“Reliability issue”

Edvaldo Santana, former director at energy regulator ANEEL and a columnist for Valor, said the blackout was one of the most significant in recent memory. The August 2023 outage cut 22.5GW of supply, while a 2010 failure involving Itaipu lines knocked out about 11GW.

Mr. Santana questioned how a fire in a single reactor—typically considered a minor contingency—could affect the entire country, especially during low demand at around 12:30 a.m. “Even for a critical substation, a reactor fire should have been contained locally. This is a serious reliability issue,” he said.

Industry sources described the Bateias substation as strategically important, part of a high-capacity 500kV line, but said it should have withstood the failure. The widespread impact indicates the system is “sensitive” to minor incidents, they said.

Experts warned the event reinforces a troubling conclusion: Brazil’s grid remains “on a knife’s edge,” not due to energy shortages but because of a combination of structural weaknesses. These include fragile transmission infrastructure, equipment failures, excessive daytime solar generation followed by steep nighttime demand ramps, and networks that remain ill-equipped for extreme weather events.

Repeat of a known pattern

The event echoed a familiar pattern seen since the August 15, 2023 blackout. An ONS report blamed that outage on voltage control failures in wind and solar farms. Since then, the operator has adopted a more conservative management approach.

Still, Brazil has experienced at least five major blackouts since then. Even minor incidents have had an impact. In August last year, a short circuit at an Eletrobras substation caused by a stray kite left 942,000 households without power in São Paulo and Guarulhos.

Heavy rains also knocked down transmission lines and damaged dams in Rio Grande do Sul, while storms cut power to millions in the São Paulo metro area. In both cases, authorities struggled to respond quickly, leaving consumers in the dark for days.

Specialists advocate for capacity auctions and technologies such as batteries and reversible power plants to improve grid resilience.

“Until 2021, utilities invested R$18 billion a year. By 2025, that number will rise to R$46 billion. From 2025 to 2029, we expect R$235 billion in total investments, with 40% focused on modernizing networks,” said Ricardo Brandão, executive director for regulation at the Brazilian Association of Electricity Distributors (ABRADEE).

The blackout comes just as Brazil prepares to transition from the dry season to the rainy period, which starts in November. There is still uncertainty over rainfall patterns and the recovery of hydropower reservoirs. Operational challenges are compounded by the rapid growth of renewables and pricing distortions that create additional costs for consumers and threaten the sector’s balance.

Brazil narrowly avoided two national blackouts this year, one in April and another on Father’s Day, August 10. With low daytime demand, rooftop and small-scale solar generation surged to record levels, forcing ONS to disconnect large wind and solar parks to avoid overloads. Such incidents occur when the grid lacks infrastructure to carry excess generation, or when supply outpaces demand.