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Retrospect

Waters tamed

Thirty years ago, work started on Itaipu, the largest hydroelectric power plant in the world

In January 1975, the tractors entered the building site and, still under the command of a few men, started to clear a patch of forest close to the city of Foz do Iguaçu, in Paraná, on the frontier with Paraguay. Some years later, this work was to become known world-wide as one of the seven marvels of modern engineering, the largest ever built in Brazil. The Itaipu Binational Hydroelectric Power Plant came to have as many as 40,000 persons working at the same time to tame the waters of the Paraná River, to dig out earth and rock (8.5 times more than the volume taken out for the Eurotunnel), and to produce a quantity of concrete with no equal (enough to build 250 Maracanã Stadiums).

This adventure, in which the figures are so big, also had some tragic aspects – many areas were inundated and the splendid set of small waterfalls know as Salto de Sete Quedas disappeared under the lake formed by the hydroelectric power plant. Itaipu started to take shape in 1966, when Brazil and Paraguay decided, officially, to take advantage of the formidable water resources of the region.

In 1970, the two countries hired an international consortium to do the feasibility studies and to begin the project (Itaipu Binational was created four years afterwards). The original idea was to make several power plants along the Paraná River – the problem is that, by diverting the river from the Brazilian bank, the frontier between the two countries would change. There was also another obstacle: what determines the production is the fall of water in the river.

The spot with the highest fall, 120 meters, is where the power plant was installed, and not in the area originally foreseen. In the end, the option was taken for building a large hydroelectric power plant with an installed capacity of 14,000 megawatts. It was Brazilian and, in lesser numbers, Paraguayan engineers, technicians and workers who made Itaipu (“stone that sings”, in Tupi-Guarani), with the effective collaboration of a consortium of companies like Siemens and Asea Brown Boveri (ABB), which produced the equipment. A Hindu engineer, Gurmukh Sarkaria, created the layout of the power plant, chose the ideal place, and the most economic formula for the dam. He opted for using the technique known as alleviated gravity (or cathedral format), a way of containing efficiently the weight of the water and economizing concrete.

The 18 columns that underpin the wall of the dam are hollow, but are just as resistant as if they were solid. The difference is that the consumption of concrete, already colossal, would grow significantly. Itaipu called for other technological solutions. At the time, a concrete laboratory was created to provide support for the engineers. Afterwards, software called Scada was especially created to accompany the power plant’s production and operation. “Our system for measuring electricity makes it possible to get a greater quantity of data about electricity production and may interest large scale power plants, like Three Gorges, under construction in China”, says the Brazilian director-general of the binational company, Jorge Samek. The Chinese work will have a larger reservoir than the Brazilian-Paraguayan one, and greater generating capacity (18,000 megawatts, compared with Itaipu’s 14,000 megawatts). But as the flow of the Paraná River is more stable than that of the Yang-tse River, the yield in China will be smaller. Three Gorges should produce 84 billion kilowatts (kWh)/year. In 2000, Itaipu produced a record 93 billion kWh. With the installation of the last two turbines (of a total of 20), this mark should be surpassed.  And the Technological Park is under construction, a binational investment to support the technological and social development of the Three Frontiers region and of Mercosur.

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