Brazil’s electric system operator warns that 8 hydroelectric reservoirs may collapse by November

RIO DE JANEIRO, BRAZIL – The reservoirs of at least eight large hydroelectric plants in the Southeast region should reach near total collapse by November 30, the end of the dry season, according to a technical note submitted by the National Electric System Operator (ONS) to the National Water Agency (ANA).

These power plants, located in the Paraná River basin, add up to 10,000 megawatts (MW) of power and represent 53% of all water storage capacity in Brazil.

Alert to collapse of eight hydroelectric reservoirs by November. (Photo internet reproduction)In the document, signed by two of its directors, the agency in charge of the sector’s operation forecasts the behavior of reservoirs during the rest of the dry season.

The scenario is appalling: the Furnas, Nova Ponte, Itumbiara, Emborcação and São Simão dams will exhaust their useful volumes before rainfall returns. The hydroelectric plants of Mascarenhas de Moraes, Água Vermelha and Marimbondo will end the dry season at less than 2% capacity.

The reference scenario used by ONS foresees the repetition of the hydrological pattern of 2020, which was critical, and the maintenance of the current flow rules in the plants – how much water can enter and leave the reservoirs in order to preserve other uses, such as human supply, irrigation, waterway transport, fishing and even leisure activities.

ONS directors Alexandre Nunes Zucarato (planning) and Sinval Zaidan Gama (operations) recommend a number of measures to prevent the complete depletion of reservoirs and minimize the risk of power shortages.

Otherwise, they alert, “there will be an almost complete depletion of all resources” in November and it would be necessary to “use the operating reserve in order to avert a deficit” in supply.

“Considering the affluence forecasts obtained with the 2020 rainfall, the loss of hydraulic control of reservoirs in the Paraná River basin is expected in the second half of 2021,” the ONS states in one of the final sections of its technical note.

“The loss of hydraulic control in the Paraná basin would imply restrictions on energy service in the South and Southeast/Midwest subsystems.”

According to experts, this would increase the likelihood of blackouts, since the system would be excessively vulnerable to minor fluctuations and unforeseen events, such as a consumption peak and technical limits on transmission from one region of the country to another.

Among the measures recommended by ONS are a reduction in the minimum quota (water mirror height) at Ilha Solteira (SP), which would impair the navigability of the Tietê-Paraná waterway for several months, and a higher flow from the Furnas reservoir, which is close to the headwaters of the Rio Grande, to feed the water flow coming into the dams later.

This change may restrict fish farming and has been criticized by Senate president Rodrigo Pacheco (DEM-MG), who fears a negative impact on the regional economy.

ONS also foresees the use of up to 20,000 MW of thermoelectric power plants between October and November. Currently, a little over 10,000 MW are connected. In practice, this would mean activating even diesel-powered thermoelectric plants, the most expensive and polluting in the whole system.

Should the changes suggested by ONS be accepted, the operator foresees that these 8 plants could survive the risk of collapse, reaching the end of November and ending the dry period with useful volumes of 2% to 6.4% – depending on the reservoir.

Thus, within the framework described as the “sensitivity scenario” by ONS, simulations point to a surplus of 3,300 MW of power in November – thus preventing, at most, the adoption of restrictive measures for energy supply.

The surplus would be concentrated in the Northeast region and would require the maximum increase of generation in the Northeast, with energy transfer to the Southeast.

For PSR consultant and ex-president of the Energy Research Company (EPE) Luiz Barroso, the scenario outlined in the technical note is excessively negative. “Maybe they were slightly dramatic in the request. I have a slightly less pessimistic outlook,” says the expert, one of the most renowned in the market.

“For ONS, it is precisely this flexibilization of minimum flows that would allow them to avert loss of operative control.”

Luiz Eduardo Barata, former director-general of ONS, believes the scenario is alarming and recalls that when reservoirs are under 10% capacity, hydroelectric plants may simply not respond to the request to generate energy – due to the risk of damage to the turbines for lack of “fuel”, that is, water flow in sufficient amount.

According to the document sent to ANA, the average capacity of reservoirs in the Southeast/Midwest (the two regions form a single operating subsystem) would reach the end of November at 7.5%. By the same time in 2001, the year of energy rationing, storage was at 23.1% of the total.

“Our situation is very different from 2001. At that time, we had to use emergency power plants, of very poor quality, or collapse,” says Barata, who was also executive secretary for the Ministry of Mines and Energy.

“Now, with renewable sources, we have very fast quality generation. The point is to tackle the scenario with transparency and to change paradigms. You can’t solve the problems of the present with the tools of the past.”

Through its advisory, ANA reported that “flexibilities and other measures deemed necessary to address the situation are under consideration.” The analyses will be made case by case, according to the reality of each region, said the regulatory agency.

Source: Valor