The Itaipu Dam.

Although several groups from the Silkroute Club have visited the Iguazu Falls, I think that PanAm 2006 are the first group to visit the nearby Itaipu Dam. The guide books stress that it is the biggest hydroelectric dam in the world (it supplies 26% of Brazil's power and 78% of Paraguay's power), some books suggest it is one of the seven wonders of the modern world. Even with this buildup we were unprepared for the reality!

When we arrived at the dam visitor's centre yesterday (Sunday) we met Lourdes Noguera Espinoza and Graciela Mantsito, who between them arranged for us to camp at the delightful Refugio Biológico Tati Yupi, one of the many reserves and parks that surround the Itaipu lake created by the dam.

Today when we returned to the visitor's centre, Lourdes and Graciela arranged a VIP tour for us. (Thank you!) For me this has been one of the highlights of our time in South America. Highly recommended.

The photograph above shows the spillway chutes in the foreground and the main dam in the centre. Note the group of nine penstocks (giant water pipes) on the Paraguay (left) side of the dam and the two groups of six and three penstocks on the Brazilian (right) side.

The international border runs thru the middle of the six storey building in the centre of the main dam.

Mick, Mo, Stephen, Judy, Rene, Mike, Lourdes and Graciela in front of the dry spillway chutes at the start of our tour.

Any water that runs down the spillway is wasted (it does not generate electricity).

In August 2006, all the available water was being used to generate electricity.

Mike stands in front of penstock #9.

Each penstock is 10.5 metres in diameter and 142 metres in length, feeding water into a single turbine.

At full flow, 690 cubic metres of water flows thru each penstock every second.

Because Paraguay uses 50Hz. and Brazil uses 60Hz. there are two slightly different types of generator (nine of each type) in the powerhouse.

The photograph shows the access floor located above seven of the eighteen generators.

Stephen stands in front of the awesome shaft joining one of the turbines (below) with its generator (above).

Lots of Numbers!

The dam was constructed between 1975 and 1983 and is 7.7km long with a maximum height of 196 metres (65 storeys). The volume of concrete poured was 15 times that of Eurotunnel. The powerhouse is 1km long, 99 metres wide and 112 metres high.

Each of the eighteen generators produces 700MW at 18kV. And just in case you wanted to know the 50Hz. generators run at 90.9 rpm, the 60Hz. ones at 92.3 rpm.

For more

Whilst the powerhouse is impressive, the scale of the dam itself is very hard to grasp. I had expected the body of the main dam to be solid, but it is in fact made up of a series of hollow buttresses.

The photograph (left) is a composite of five photographs taken both upwards and downwards from level 144 (i.e. 144 meters above sea level) within one of the buttresses.

The "floor" seen at the very bottom of the photograph is at level 44 (i.e. 44 metres above sea level) and is the bed of the original river.

You can take the stairs down the 100 metres. We took one of the five elevators.

The Itaipu dam is undoubtedly on my list of thing you must see in South America.

Stephen Stewart.

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