Blackouts that closed down Brazil’s two largest cities, Sao Paulo and Rio de Janeiro, and left 60 million of the country’s inhabitants in darkness for four or five hours on the night of 10 November were caused by short circuits in a power substation that tripped three key transmission lines from the huge Itaipu hydroelectric complex on the border with Paraguay, officials of the Energy ministry said on 17 November.
The faults occurred at the substation in the Sao Paulo state town of Itabera while lightning, wind and intense rain were pounding the area, Brazil's Mines and Energy ministry said in a statement, but it is not now saying that weather caused the problem.
Earlier speculations had said that the short circuits were caused by bad weather, by interference by hackers intending to blackmail utilities, and even by the Itaipu dam itself. Heavy rain, lightning and strong winds were at first said by the Energy ministry to have caused the disaster. The weather made transformers on a vital high-voltage transmission line short-circuit, Brazil's energy minister said, which automatically shut down the lines that carry energy to much of Brazil from the Itaipu dam straddling the border with Paraguay.
Electricity from Itaipu travels along five high-capacity transmission lines to two substations about 900km to the east in Sao Paulo state. From those substations, the energy enters Brazil's national grid. The loss of power from Itaipu triggered automatic shut down of other power plants, including the country’s two nuclear generators.
It was the first time that Itaipu – which provides about 20% of Brazil's electricity – had been shut down in the dam's 25-year history. It was the largest single producer of electricity in the world until China's Three Gorges dam recently surpassed it.
More than 60 million people lost power for up to four hours in 18 of Brazil's 26 states. All of Paraguay was briefly darkened and 7 million people in Sao Paulo lost water service. The federal district that includes the national capital of Brasilia was spared.
Mines and Energy minister Edison Lobao came under fire for at first blaming severe weather, rather than accept responsibility for what is perceived as a lack of investment in the infrastructure, especially when the National Institute for Space Research said that satellite images indicated the closest lightning strikes were at least 10km from the affected transmission lines.
The cause of the short circuit is not yet known. President Luiz Inacio Lula da Silva said on Monday (17 November) that an investigation will determine why the short circuits happened and that his administration will work hard to make sure similar outages don't occur.
The president has vigorously defended his government from the charge that it has not done enough to improve the power grid since he took office in 2003, two years after Brazil suffered shortages and rationing under his predecessor. "In seven years, we created 30 percent of all the transmission lines built in the last 130 years," he said. "There was no shortage of power generation, and the problem was not a lack of transmission lines." Energy minister Edison Lobao said that Silva's government has invested about $13 billion in the transmission lines, and another $4.7 billion in transformers since 2003.
The energy minister also defended the strength of the Brazilian system — pointing out that it took a day to fully restore power after a blackout hit the East Coast of the US and Canada in 2003, leaving 50 million people in the dark. He mentioned lengthier blackouts in other countries, including Italy and Japan.
This was the fourth time since 1985 that Brazil has suffered a massive power outage blamed on transmission line failures from Itaipu. The worst occurred in 1999 after lightning struck a power substation in Sao Paulo state, plunging 97 million Brazilians into darkness for up to five hours.
