ITAIPU
"Peanuts"- a word often used from so called "economic experts" and representatives when it comes to Renewable Energies.
"Not sufficient", "unreliable", "not feasable", are common bias. ITAIPU shows they are wrong! Having more power than 10 nuclear power stations it supplies the second largest city on the planet with zero-emission electricity since 1984, still being extended until 1991. 26% of the electrical power consumption of Brazil and 78% of Paraguay are supplied by ITAIPU.
Located at the Brazilian-Paraguaian border and not far from the Argentinian border, the first step of the initiation was already in 1966 when the Ministers of Foreign Affairs of Brazil and Paraguay signed a joint statement known as the "Act of Ygazu". By this a study and evaluation of the hydraulic resources of the Parana river (owned jointly by Brazil and Paraguay) followed.
On April, 26, 1973, the two gouvernments of the states signed a treaty "for the development of the hydroelectric resources of the Parana River" and founded "ITAIPU Binacional" (a cooperation with the legal, administrative and financial capacities and technical responsibility to plan, set up and operate the plant) in May, 17, 1974.
The construction work sarted in 1975, reaching its peak in 1978 with 30 000 people at work. Monthly on-site concrete production reached 338 000 m³. In total, 15 times the mass of concrete used for the "Eurotunnel" was supplied. The height of the dam reaches 196 m, its length 7.76 km. The lake created by this is 170 km long and contains 29 billion tons of water.
Unit 1 started to operate in December 1983. Electrical grid connection to Paraguay was established in March 1984, Brazil was connected 5 months later. In March 1991 the last unit (No.18) was put into operation.
The water intake of one single 715 MW Francis-turbine is 700 m³/s, its weighted efficiency is 93.8%.
Each year ITAPU generates 75 TWh of electricity and avoids 67.5 million tons of carbondioxide emissions - compared to coal power plants.
The final cost of ITAIPU amounts to US$ 20 billion, 50% of this value are direct investments and balance financial charges.
If whole area of the lake - at nominal level - would be covered by solar modules the power of the would be 135 000 MWp, which would produce 230 TWh a year. For the same yearly output as ITAIPU a solar PV-plant would cost US$ 132 billion.
Principle of energy conversion at hydro power plants:
The potential energy given by the water stored in the lake at a certain height above the outlet. This energy is converted into cinetic energy by letting it flow down the tubes. This cinetic energy is given to the blades of the water tubine which transform it into a mechanical rotation. This rotation is used to drive the electric generatores. The electicity is generated by moving magnetic fields along conducting coils.
At ITAIPU the total potential energy of the usuable part of the lake is given by:
Wpot = 0.5 (hul +hip) (hul -hip)* g * A * r
hul= height of upper level (222 m)
hip= height of penstock inlet (187 m)
g= acceleration of free fall (9.81 m/s²)
A= area of lake (1350 km²)
r = density of water (1000 kg/m³)
Wpot,abs = 9,48 * 1016 J = 94,8 PJ
The upper result is related to sea level, while the head of the penstock is 118.4 m only, the used potential energy is:
Wpot = 5,49 * 1016 J = 54,9 PJ
The water intake of one single 715 MW Francis-turbine is 700 m³/s, its weighted efficiency is 93.8 %. So with the lake filled up the turbines can produce 13 400 GWh until the penstock inlet is out of water (if no water follows), which means 44 days full power operation of the plant.
The generators have an efficiency of 98.6 %, while the 50 Hz types with 66 poles have a rated output of 823.6 MVA at (90.9 rounds per minute) and a power factor of 0.85, the 60 Hz types with 78 poles have a rated output of 737 MVA (at 92.3 rounds per minute) and a power factor of 0,95. The output voltages are both 18 kV.
Each year ITAPU generates 75-77 TWh of electricity and avoids 67.5 million tons of carbondioxide emissions.
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