Located on the border of Brazil and Paraguay, the Itaipú Dam produced 103.09 million megawatt-hours (MWh) of electricity in 2016 — making the hydroelectric system the world’s largest power plant.
Ten years after its completion in 1984, the American Society of Civil Engineers named it “one of the seven engineering wonders of the modern world.”
Building the $27 billion Itaipú Dam required 18 years and 40,000 workers, according to PBS. Construction began in 1975, when workers carved a 1.3-mile-long, 300-foot-deep, 490-foot-wide diversion channel to re-route the Paraná River to make way for the dam. In the process, they moved 50 million tons of rock and earth and used about 12.3 million m³ of concrete (roughly enough to build 210 football stadiums). The structure also features approximately 380 times the amount of steel and iron as the Eiffel Tower.
Because of construction, approximately 10,000 families living beside the Paraná River were displaced in the early 1980s.
The concept behind the power plant started with negotiations between the Brazilian and Paraguayan Ministers of Foreign Affairs, Juracy Magalhães and Raúl Sapena Pastor, in the early 1960s. In 1966, the two countries signed a treaty that said they would explore hydropower resources in a shared section of the Paraná River (located on the border).
The negotiations inspired the construction of the Itaipú Dam, which gives power to both Brazil and Paraguay. Today, the system provides about 16% of Brazil’s energy supply and 76% of Paraguay’s.
The system is a gravity dam, meaning it relies on its own weight to resist the pressure of water that flows through it. Inside the dam, there are turbines, which turn from the water pressure and connect to electricity generators.
The dam has a capacity of 14 GW, which would be enough to power about half the state of California. Until this year, China’s Three Gorges Dam, which generated 93.5 million MWh in 2016, held the title as the world’s largest power plant in terms of annual production.
Measuring 643 feet tall and nearly 26,000 feet long, the Itaipú Dam is also the world’s largest renewable energy complex.
The project has faced controversy. In 2015, a group of Paraguayan protesters said that over 9,000 people did not receive payments for their work on the Itaipú Dam from 1974 to 1996. They told the IB Times that the former workers should receive about $40,000 each. In response, five people nailed themselves to crosses, an increasingly common form of protest in Paraguay that the Roman Catholic Church has condemned but has often been successful, according to The LA Times. A few weeks later, Paraguay’s Work Ministry agreed to meet with the protesters to discuss the wage dispute.
“As a former worker, I decided to crucify myself remembering the sacrifice of Jesus Christ,” protester Roberto Gonzalez, who was 61 years old at the time, told the AP.