Although Norte Energia Operator deems that this year’s first semester marked the completion of signatures of big contracts for Belo Monte, the hydroelectric plant (UHE) will not be operational within the deadline contractually disposed. A conjunction of problems will postpone the start of generation
Nildo Carlos Oliveira
Construction work moves ahead. However, Belo Monte – “the best hydroelectric plant in the world”, in the words of engineer José Antonio Muniz, former Eletronorte CEO and, later, Eletrobras CEO and transmission director, is late. Until the beginning of this month (August) the National Agency of Electric Energy (Aneel) was taking care of the analysis of the request for delay filed by the operator. The agency’s general manager explained that the request would undergo two main evaluations: technical and legal.
To explain the problems, the operator said that due to the loss of the hydrological window in the dry season in 2011 and 2012, the first phase of the deviation of the Xingu River, planned for December 2011, could only take place in January 2013. Additionally, the construction consortium faced 441 days of delay in the implementation of the jobsite at Pimental site, where is located the dam in charge of the main reservoir (370 km2) whose should have started to be filled up at the beginning of the year. And there were 124 idle days due to blockages at jobsites promoted by NGOs and indigenous groups. Those occurrences delay the construction of the 20-km long derivation channel and 28 dikes necessary to form the intermediate reservoir (130 km²), targeted on feeding the 18 most powerful turbines. The operator mentioned another problem: the Brazilian Institute of the Environment and of Renewable Natural Resources (Ibama). Trouble is, to fill up the reservoirs by meeting the deadlines originally disposed, Norte Energia would need to have a license for operation which, according to him, has not been granted yet.
The operator did not add to the list of reasons other problems that had been accumulating as time went by, since or even before 1975, when studies were started for hydroelectric use of the basin of the Xingu River. There were comings and goings, studies went deeper, there were changes in the pre-project phases, alterations were made in the project, there was a previous process of environmental licensing, legal demands and other delaying measures triggered by local conflicts of interests, until we finally got to 2011.
In January that year the license was granted for the UHE’s temporary facilities and in the following June, the final installation license was also granted. It was just then that the construction consortium led by Andrade Gutierrez and composed of Camargo Corrêa, Norberto Odebrecht, OAS, Queiroz Galvão, Contern, Galvão Engenharia, Serveng-Civilsan, Cetenco and J. Malucelli, actually started the construction work.
The jobsites
The hydroelectric plant, a R$26 billion investment, is being built at the basin of the Xingu River, which spreads along a 450km2 large area and records hydroelectric potential of 22 thousand
Megawatts. The jobsite is located exactly at the South-Amazon fall line, where a crystal, hard relief meets another sedimentary relief, less rigid, along which urban nuclei have been born, later being transformed in the cities of Tucuruí and Altamira.
The plant was projected with 11,233 MW installed capacity. However, in order to operate with a reduced reservoir (an imposition arising from local demand and the environmental agency), is expected to produce about 4,500 MW on average per year, which stands for about 10% of national consumption. This, in effectively installed capacity, it will be the third biggest hydroelectric plant in the world, just behind Três Gargantas (20,300 MW), in China and bi-national Itaipu (14,000 M/w).
The main constructions include the main dam 40 km down the municipality of Altamira at the Pimental site, as from where part of the water is deviated by a 20-km long derivation channel. It goes then to the intermediate reservoir, 50 km far from that urban nucleus. Originally the project disposed to derivation channels. Further changes recommended that only one should be built. And this one closes the draining in the region through 27 dikes.
The main spillway is located at the dam of Pimental site. It was dimensioned with 20 gates 20m x 22.3m large with a maximum flow of 62,000 m3/s. At that site was built a ladder to ease the Piracema phenomenon. .
The plant has two powerhouses, the main one at the Belo Monte site, slight upstream to the village named after the plant. It will operate with 11 Francis-type hydraulic turbines with total installed potency of 11 thousand MW and 13,950 m3/s total flow.
The main dam is only 35m high. Nevertheless, the Xingu River’s natural slope in the stretch with reduced flow will make the liquid fall 87m high. The complementary powerhouse is being built next to the main dam and it will shelter six bulb-type turbines with 233.1 MW potency, 11.4m liquid fall and total flow by turbines of 2268 m2/s.
About the turbines, the construction consortium had emphasized the structural works required to shelter them and intended to complete them by the end of this year. The coating of the suction tubes of turbines 5 and 6, on the other hand – the last one at the Pimental site – was started in September 2013 and was completed last February. Each coating weighs about 35 t, equivalent to a little more than 3% of the weight of 1,100t of each one of the six bulb-type turbines of the complementary powerhouse. .
At the beginning of this semester, Norte Energia had signed contracts worth R$1,26 billion to do electromechanical assembling at Belo Monte’s powerhouse (the main one) and Pimental (secondary one). The set of assembling works involves 141 thousand t of machines.
Transmission system
Norte Energia points out that this year’s first semester was decisive for it to deem ended the cycle of signature of big contracts for the hydroelectric plant. After the deals closed for electromechanical assembling in Belo Monte and Pimental, it signed contracts worth
R$ 179.3 million with the companies Isolux and São Simão to build the restricted transmission system of the plant. The system is composed of a set of transmission lines and substations that will take the power generated at the two powerhouses to the National Interlinked System. And it is from there, when Belo Monte UHE is ready, that the power generated will reach 60 million Brazilians in 17 states.
The transmission line to drain the power which, according to the operator will be the first one in South America to operate with 800 kV, was auctioned last February by Aneel. The restricted transmission system of Belo Monte will by composed of 65km of 230kV transmission lines. It will drain the power generated at Pimental and there will be 67.6km of fiv
e 500kV lines to carry the power produced in Belo Monte.
According to the first forecast, the 230kV transmission line should be completed by September 2015 and the 500kw transmission line, in December that same year. However, according to an official letter sent by the operator to Aneel, commercial generation of the first turbine at Belo Monte will be postponed from March 2016 to March 2017, and the 18th machine that will complete the 11,233 MW is expected to be operational only as of January 2020.
Fonte: Revista O Empreiteiro
