Itaipu Hydroelectric Dam, Brazil
Itaipu Hydroelectric Dam is the largest operational hydroelectric energy producer in the world, with an installed generation capacity of 14GW. The plant is operated by Itaipu Binacional and located on the border between Brazil and Paraguay. Energy generated by Itaipu helps meet demands from the two countries. About 90% of the energy generated by the plant is used by Brazil.
The dam and the plant are on the Paraná River. Construction of the dam began in February 1971 and cost $19.6bn. The first unit began generating power in May 1984. The second generating unit started operating the same year. As of 2009 Itaipu has 20 generating units, each with a capacity of 700MW.
The dam's reservoir, which covers an area of 1,350km², is the seventh-largest reservoir in Brazil, with a best coefficient of water utilisation of 10.4MW/km². Itaipu generated 94.68 billion kWh of energy in 2008, sufficient to meet worldwide power consumption for two days.
It is equal to the energy consumed by Paraguay for 11 years and by Argentina for one year.
The energy generated in 2008 was used to supply 87% of the electricity consumed in Paraguay and 19% demanded by the Brazilian interconnected system.
The proposal for construction of Itaipu was made in February 1971. Paraguay and Brazil signed a treaty in April 1973 for the exploitation of the Paraná River by both countries for hydroelectric power. The treaty put the maximum number of generating units at 18. The plant has two other units as reserve.
Itaipu Binacional was created in May 1974 to undertake Itaipu's construction. Construction of the plant began in January 1975.
The first two units of the plant were installed in 1984 while the 19th unit was installed in 2006. The plant was completed with the installation of its 20th unit in 2007.
An environmental study was taken up by the Meteorological System of Paraná (Simepar) from September 1997 to 2000. It found that the reservoir did not influence the climate of the region.
The treaty, when originally signed, required Paraguay to sell its unused electricity to Brazil for $124m a year until 2023. The treaty expires this year and has caused widespread discontent in Paraguay for a number of years.
In July 2009 the two countries signed a deal, under which Brazil agreed to triple its payments to Paraguay. It also permitted Paraguay to sell excess power directly to Brazilian companies instead of going through the Brazilian electricity monopoly. The deal also includes construction of an electricity line, which will be completed by 2012.
A consortium of US-based IECO and Italy-based ELC Electroconsult carried out the viability studies of the project and its construction.
The Itaipu project included the construction of a 7,919m-long and 196m-high dam. The dam was built to form an artificial lake that accumulates water. Itaipu's main dam is made from concrete while the auxiliary dams are made from rockfill and earthfill rocks and earth from local excavations.
Construction of the dam involved installing four rock crushing centres, two on each bank, with a total capacity of 2,430t/h, and six concrete mixing plants with a capacity of 180m³/h each. The site also includes two monorails, seven aerial cableways and 13 tower cranes. The dam used 12.3 million m³ of concrete.
The power plant includes a turbine, generator, excitation system and speed governor. All units are separated by a distance of 34m. The power plant has three substations, of which two are gas insulated and one is a conventional 50Hz substation.
The installed generation capacity of the plant is 14GW while the instantaneous generation and accumulated generation capacities are 10.571MW and 85 million MWh. The accumulated generation of the plant is 1.6 billion MWh.
The plant utilises a hydrometeorological telemetry system (HTS) to obtain data for forecast, supervision and operations control. This model reads information from sensors and relays them to the plant through satellite and the internet.
Furnas Centrais Elétricas of Brazil and Administración Nacional de Electricidad (ANDE) of Paraguay are responsible for transmission of power to load centres.
Power generated by Itaipu is distributed through an interconnected system. The system is connected from Brazilian substation Foz do Iguaçu, owned by Furnas, to the Paraguayan right bank substation within the plant's area.
The two gas insulated substations of the power plant are of 50Hz and 60Hz. The 50Hz substation contains six 500kV transmission lines. Two lines are 2km long and link the power plant to the right bank. Two 10km-long lines connect the power plant to the Foz do Iguaçu substation. The remaining two transmission lines connect the right bank and Foz do Iguaçu substations.
The 60Hz substation contains three to four 500kV transmission lines. Each line links the power plant to the Foz do Iguaçu substation.