The nearly completed Simplício Hydroelectric Complex in Brazil, owned by the government-run Eletrobrás Furnas, has been a Herculean construction project that began in 2007 and is expected to finish in late 2012. Constructed by the Construction Consortium of companies Odebrecht and Andrade Gutierrez, the project has received worldwide acclaim for its engineering ingenuity, level of construction difficulty, and expansive 15-mile-long site.
With Brazil scheduled to host two of the world’s largest and most prominent athletic events, preparations are underway to shore up the electric grid infrastructure before the 2014 Soccer World Cup and the 2016 Summer Olympic Games arrive. Only one month after securing the Olympic bid, Brazil endured a harsh reminder of its aging electric infrastructure: in one of the largest blackouts in human history, 60 million people—including the entire population of Rio de Janeiro—were left in the dark for three hours after a storm struck a key transmission line near the Itaipú hydroelectric dam on the Paraguay-Brazil border.
The Itaipú hydroelectric dam is a crucial power source for Brazil, alone accounting for 20% of Brazil’s power needs. The massive Itaipú hydroelectric plant is also the world’s second-largest, with an output of 14,000 MW. However, since the Itaipú plant is located 1,000 miles from Rio de Janeiro, the transmission lines remain vulnerable to future blackouts.
Commonly known, an electric grid is comprised of transmission and distribution power lines that conduct electricity from the power source to each point of use. Power lines are comprised of conductive cables made of either aluminum or an aluminum and steel combination. The electricity is then sent in three phases, each one on an independent cable, separated by a distance determined by the amount of current in the lines. When a tree branch, for example, falls onto two of the phases, the power short-circuits, leaving customers in the dark.
To safeguard against power outages, Rio de Janeiro is being turned into an electric island, one with a power grid isolated from the rest of the country. The key to supporting the power island plan is the new Simplício Hydroelectric Complex, located 90 miles north of Rio de Janeiro. The hydroelectric complex will include two power plants with a sum total capacity of 333.7 megawatts, which results in a 30% boost to Rio’s current electric supply.
The Greeks are perhaps most famous for giving the world the Olympic Games, but they are also credited with the invention of hydropower, the precursor to hydroelectric power, upon which Brazil is now dependent. When it was invented 2,000 years ago, hydropower provided a means to grind wheat into flour; today, hydropower offers a renewable energy source that accounts for 16% of power generation worldwide. Hydroelectric power uses the natural flow of water to spin turbine blades and a generator that produces electricity.
The project scope
The Simplício Construction Consortium is an equally shared partnership between Odebrecht and Andrade Gutierrez for the design, engineering, and construction of the Simplício Hydroelectric Complex, with Odebrecht designated as the leader. Both companies are Brazilian and work internationally on a wide range of projects, including large portfolios of hydroelectric plant construction projects.
Construction entails diverting the Paraíba do Sul River away from large population centers so that the river’s necessary reservoirs will not flood developed areas. Rerouting the river 15 miles off its natural course requires new infrastructure, including: eight dams, eight canals, five reservoirs, and seven mountain tunnels. Fernando Chein Muniz, Project Manager of Odebrecht, says, “The concept is simple, but to build it is very complicated.”
The start of the river’s new path is the first dam located at the existing Anta plant. Then, the end of the path is where the larger Simplício plant now resides with its three steel-encased penstocks that each lead to an enormous Francis turbine, among the most advanced turbines in the world. The entry of the spiral turbine begins at a 13-foot diameter size and ends at a four-foot diameter end. The physics of the tapered diameter ensure a constant flow of water. As the water gushes against the sides of the turbine, it slows down, but a narrowing aperture naturally converses an increase to the flow rate.
Tunneling through seven mountains
The chain of tunnels through seven mountains created for the new Simplício plant were engineered with a calculated diameter that maintains a proper flow rate for the river, while at the same time not constricting it. A tunnel that is too narrow could result in uncontrolled flooding that would disrupt fragile ecosystems. All in all, an estimated 88 million cubic feet of rock was removed from the seven tunnels using a combination of Jumbo drills and explosives to excavate a total length of 6.4 miles.
The tunnel blasting was performed in a two-step process. First, the top semicircle of the tunnel was blasted to a height of 26 feet and then 52 strategically located holes were drilled to 20 feet deep. The holes were filled with liquid explosives and connected by fuses that created a circuit of timed blasts. Once the fuses were lit, workers had only seven minutes to vacate the area. This explosion process was repeated every couple hundred of feet along the course of the tunnels.
A delicate lift
The three spiral turbines at the Simplício Plant total 62 tons each and are built on-site from steel plates. Water is fed from the bottom of the reservoir to the underground penstocks, and finally to the turbines. The penstocks are sloped at seven degrees and cover a total fall of 100 feet. Once the water arrives at the turbines, the force is so powerful that the steel casing of the turbines must be buried in concrete for rigid support.
Yet before the concrete could be poured, the turbines were checked for water-tightness. To do so, a giant plug of 16 tons of steel and 15 feet in diameter was crane-lifted from 90 feet above the turbines and lowered to fit within only 1/64th of an inch of clearance. If there had been one miscalculated move of the crane, the turbine shell could have been easily crushed. Fortunately, the plug was lifted and placed without a hitch.
Managing the site
Rerouting the river to its new 15-mile stretch meant that the construction site was equally as long. As such, managing a large site is no small challenge, as Ivan Bronzatti, an Odebrecht Administrator, recognized, “It is totally different from a centralized project, and all our strategies have to be analyzed and planned with that situation in mind, so that the resources used to support production are utilized well. We have three main jobsites, five medical centers, four ambulances, six cafeterias, and a fleet of 35 buses to transport 2,500 workers.”
Not only did the project present many logistical challenges, it also required a lot of pre-planning and preparation work. Before mobilization of construction could begin, 50 miles of roadways were either widened or built to provide access to all areas of the site. Additionally, four data and voice transmission towers were erected to support complex communication needs and large numbers of skilled laborers were hired.
Rio’s electrical needs
The electrical demands for Brazil are only expected to increase—not simply due to the influx of tourism expected for the upcoming world games, but to fulfill the needs of an ever-increasingly developed nation. Of note, power demands have doubled within the past 25 years and a similar trajectory is expected to continue.
Since Brazil has an abundance of fresh water—20% of the world’s supply—hydroelectric generation is a convenient choice. In fact, 80% of Brazil’s energy comes from this renewable source, and, with many rivers yet untapped, there are still plenty more opportunities for additional hydroelectric plants.
Brazil boasts of being one of the world’s leaders in renewable energy use because of the abundance of its hydroelectric plants. Yet there remains a risk to having such a heavy reliance on rainfall. Drought has affected Brazil in the past, and some researchers project the world’s changing climate will reduce rainfall in the future. Hydroelectric power is also susceptible to controversy as dams and reservoirs affect surrounding ecosystems to one extent or another.
The world will be watching
When populations from around the globe tune in to watch the upcoming athletic events in Rio de Janeiro, the world will see a transformed Brazil that has invested a total of $14 billion into its infrastructure alone. In fact, a contributing reason that Rio was awarded the Olympic bid was to provide Brazil with the opportunity to improve its infrastructure.
The anticipated successful construction of the Simplício Hydroelectric complex will provide safer levels of electric accessibility to all. In an amazing feat, the construction consortium of Odebrecht and Andrade Gutierrez has already shown the world a gold-medal performance.
From the September-October 2012 issue of the Wire Rope Exchange.
By: Olivialin A. Miller, P.E.