Itaipu (Guarani: Itaipu, Portuguese: Itaipu, Spanish: Itaipú; Portuguese pronunciation: ], Spanish pronunciation: ]) is a hydroelectric dam on the Paraná River located on the border between Brazil and Paraguay.
The name "Itaipu" was taken from an isle that existed near the construction site. In the Guarani language, Itaipu means "the sound of a stone". The American composer Philip Glass has also written a symphonic cantata named Itaipu, in honour of the structure.
Itaipu Binacional is the company that runs the largest operational hydroelectric power plant in the world. The dam is second only to the Three Gorges Dam in its generating capacity. It is a binational undertaking run by Brazil and Paraguay at the Paraná River on the border section between the two countries, 15 km (9.3 mi) north of the Friendship Bridge. The project ranges from Foz do Iguaçu, in Brazil, and Ciudad del Este in Paraguay, in the south to Guaíra and Salto del Guaíra in the north. The installed generation capacity of the plant is 14 GW, with 20 generating units providing 700 MW each. In 2008 the plant generated a record 94.68 billion kilowatt-hours (kWh), supplying 90% of the energy consumed by Paraguay and 19% of that consumed by Brazil.
The concept behind Itaipu Power Plant was the result of heavy negotiations between the two countries during the 1960s. The "Ata do Iguaçu" (Iguaçu Act) was signed on July 22, 1966, by the Brazilian and Paraguayan Ministers of Foreign Affairs, Juracy Magalhães and Sapena Pastor, respectively. This was a joint declaration of the mutual interest in studying the exploitation of the hydric resources that the two countries shared in the section of the Paraná River starting from, and including, the Salto de Sete Quedas, to the Iguaçu River's watershed. The Treaty that gave origin to the power plant was signed in 1973.
The terms of the treaty, which expires in 2023, have been the subject of widespread discontent in Paraguay. The government of President Lugo vowed to renegotiate the terms of the treaty with Brazil, which long remained hostile to any renegotiation.
In 2009, Brazil agreed to a fairer payment of electricity to Paraguay and also allowed Paraguay to sell excess power directly to Brazilian companies instead of solely through the Brazilian electricity monopoly.
In 1970, the consortium formed by the companies IECO (from the United States of America) and ELC Electroconsult S.p.A. (from Italy) won the international competition for the realization of the viability studies and for the elaboration of the construction project. Work began in February 1971. On April 26, 1973, Brazil and Paraguay signed the Itaipu Treaty, the legal instrument for the hydroelectric exploitation of the Paraná River by the two countries. On May 17, 1974, the Itaipu Binacional entity was created to administer the plant's construction. The works began in January of the following year.
On October 14, 1978, the Paraná River had its route changed, which allowed a section of the riverbed to dry so the dam could be built there.
An important diplomatic settlement was reached with the signing of the Acordo Tripartite by Brazil, Paraguay and Argentina, on October 19, 1979. This agreement established the allowed river levels and how much they could change as a result of the various hydroelectrical undertakings in the watershed that was shared by the three countries. At that time, the three countries were ruled by military dictatorships. Argentina was concerned that, in the event of a conflict, Brazil could open the floodgates, raising the water level in de la Plata River and consequently flood the capital city of Buenos Aires.
The plant's reservoir began its formation on October 13, 1982, when the dam works were completed and the side canal's gates were closed. Throughout this period, water rose 100 meters (330 ft) and reached the gates of the spillway at 10 a.m. on October 27 due to the heavy rains and flooding that took place at the time.
On May 5, 1984, the first generation unit started running in Itaipu. The first 18 units were installed at the rate of two to three a year; the last two of these started running in the year 1991.
The last two of the 20 electric generation units started operations in September 2006 and in March 2007, thus raising the installed capacity to 14 GW and completing the power plant. This increase in capacity will allow for 18 generation units to remain running all of the time while two stay down for maintenance. Due to a clause in the treaty signed between Brazil, Paraguay and Argentina, the maximum number of generating units allowed to operate simultaneously cannot exceed 18 (see the agreement section for more information).
The rated nominal power of each generating unit (turbine and generator) is 700 MW. However, because the head (difference between reservoir level and the river level at the foot of the dam) that actually occurs is higher than the designed head, the power available exceeds 750 MW half of the time for each generator.
Each turbine generates around 700 MW; by comparison, all the water from the Iguaçu Falls would have the capacity to feed only two generators.
On November 10, 2009, transmission from the plant was totally disrupted, possibly due to a storm damaging up to three high-voltage distribution lines . Itaipu itself was not damaged. This caused massive power outages in Brazil and Paraguay, blacking out the entire country of Paraguay for 15 minutes, and plunging Rio de Janeiro and São Paulo into darkness for more than 2 hours. 50 million people were reportedly affected. The blackout hit at 10:13 p.m. local time. It affected the southeast of Brazil most severely, leaving São Paulo, Rio de Janeiro and Espírito Santo completely without electricity. Blackouts also swept through the interior of Rio Grande do Sul, Santa Catarina, Mato Grosso do Sul, Mato Grosso, the interior of Bahia and parts of Pernambuco, energy officials said.
By 12:30 a.m. power had been restored to most areas.
Itaipu, which straddles the border between Brazil and Paraguay along the Paraná River, supplies about 20% of Brazil’s power and 90% of the energy consumed by Paraguay.
Of the twenty generator units currently installed, ten generate at 50 Hz for Paraguay and ten generate at 60 Hz for Brazil. A 50-to-60 Hz frequency converter in Brazil makes use of excess 50 Hz power from Paraguay.
When construction of the dam began, approximately 10,000 families living beside the Paraná River were displaced.