The plant with the greatest potential for generating hydroelectric energy in Goiás is located in Itumbiara, in the south of the state, and is generating less energy than in August 2001, when there was a blackout in Brazil. According to data from the National Electric System Operator (ONS), the unit had an average reservoir water level of 11% 20 years ago and currently works with 10%.
Also according to ONS data, the Itumbiara plant is capable of producing around 2,083 MW (megawatt), however, with the amount of water above the turbines (useful volume) low, the plant ends up generating less energy.
According to Furnas, who manages the plant, on Monday (6) the unit’s average energy generation was 388 MW, which corresponds to 19% of its capacity.
On the same date in 2001, the reservoir level was 11.8%. Applying the same proportion, production was 21.3% of capacity, therefore 437 MW – more than is currently produced.
Itumbiara hydroelectric power plant — Photo: Reproduction/Furnas
To get a sense of what this production represents, the G1 consulted an expert in the field. According to electrical engineer Victor Bitencourt, 500 MW is enough power to supply the average energy demand of a city of about 1 million inhabitants, instantly.
The engineer also explained how the power production capacity of the plants works when they have a low volume of water in the reservoirs.
“This useful volume does not change the capacity of the plant, but it limits energy generation [para que o nível não abaixe a ponto de não ter mais água suficiente]. What you do is not generate everything so as not to go down too much [o nível da água], or generate according to the amount of water that arrives”, explained electrical engineer Victor Bitencourt.
Itumbiara Hydroelectric Reservoir Level
This “amount of water that arrives” is called affluence. According to the ONS, Brazil is currently facing the “lowest affluences in the last 91 years in the National Interconnected System (SIN)”.
Despite the delicate situation, the agency highlighted that “it is taking all the appropriate technical and operational measures to maintain the continuity of service to electricity consumers in Brazil.”
ONS maps and evaluates the plants that are part of the SIN. In addition to these units, according to the agency itself, there are smaller generators that also sell energy, but are not part of the system, therefore they are not mapped by the Operator.
“This period is critical and the smallest hydroelectric plants end up stopping or working only part of the day, for example,” said Victor.
Locations of ten hydroelectric plants in Goiás — Photo: CGA/TV Anhanguera
ONS provides data on the level of reservoirs and energy production of ten hydroelectric plants in Goiás. Check below the average percentage of the amount of water in each plant in August and how much each one generated in MW in the most recent record:
Average useful volume in August 2021: 21.6%
Capacity: 53 MW
Generated on September 2nd: 8 MW
Average useful volume for August 2021: 96%
Capacity: 65 MW
Generated on September 2nd: 14 MW
Average useful volume for August 2021: 67%
Capacity: 375 MW
Generated on September 2nd: 127 MW
Average useful volume for August 2021: 88%
Capacity: 96 MW
Generated on September 2nd: 32 MW
Average useful volume for August 2021: 62%
Capacity: 127 MW
Generated on September 2nd: 45 MW
Average useful volume for August 2021: 47%
Capacity: 32 MW
Generated on September 2nd: 20 MW
Average useful volume for August 2021: 11%
Capacity: 2,083 MW
Generated on September 2nd: 439 MW
Useful volume for August 2021: 20%
Capacity: 1,710 MW
Generated on September 2nd: 710 MW
Serra do Machado
Useful volume for August 2021: 24%
Capacity: 213 MW
Generated on September 2nd: 100 MW
Useful volume for August 2021: 27.3%
Capacity: 1,275 MW
Generated on September 2nd: 824 MW
Hydroelectric reservoir in Goiás – file image — Photo: Reproduction/TV Anhanguera
To continue supplying the demand for electric energy even with hydroelectric plants generating less, electrical engineer Victor Bitencourt explained that it is necessary to activate thermal plants that also produce energy, but in a more expensive way.
“In this crisis, the electrical monitoring committee needs to activate the emergency thermal plants, which have a system based on common diesel, the same as the truck. In Goiás we have four of these. The problem is that the cost is much higher,” he said.
A chart by the Electric Energy Trading Chamber (CCEE) shows that the average price in the Midwest is over R$ 580 – the highest in the last three years.
Energy price according to Electric Energy Trading Chamber — Photo: Reproduction/CCEE
Asked by the G1 on the ways in which this reality can be circumvented, electrical engineer Victor Bitencourt explained that one of the solutions is to invest in other energy sources.
ONS itself already foresees a gradual change in this production for the next few years:
Forecast of changes in energy sources in Brazil — Photo: Reproduction/ONS
“In the long term, Brazil has evolved immensely. The exponential growth of wind power plants, solar power plants has increased. […] Today, the expectation is that wind energy represents 11%, with a forecast to grow to 13%. Storage batteries, green hydrogen generation will soon arrive. There is a lot of research and development in this,” he detailed.
See other news from the region at G1 Goiás.