ONS estimates up to three years for reservoirs to return to optimal levels

Despite the improvement in the country’s water scenario, with the beginning of the rainy season and gradual recovery of reservoir levels, the National Electric System Operator (ONS) estimated, at the request of CNN, which will take up to three years for these reservoirs to return to levels considered ideal for storage. The agency, however, did not inform what would be the ideal capacity, justifying that this number varies between reservoirs.

Despite this, the agency predicts that by April of next year, in an optimistic scenario, it will be possible to double the level of reservoirs in the Southeast/Midwest subsystem, responsible for around 70% of energy generation in Brazil.

This optimistic scenario in relation to the Southeast and Center-West reservoirs will occur if the good prospects for rain are confirmed during the wet season in the country, which usually occurs between October and March. The ONS, however, highlights that the scenario is still of attention and that the projections are subject to changes according to the rainfall index for the coming months.

Former director of the ONS for eight years and member of the Climate and Society Institute (ICS), Luiz Eduardo Barata understands that, in fact, the federal agency does not work with what it classified as a target level, but said it is possible to establish a parameter of recomposition mainly focused on the level of the Southeast/Midwest subsystem.

“The ONS can consider the level of the reservoirs in an isolated way, but it can also consider the level of all the reservoirs. I would set a target of 80% for the Southeast reservoirs. That would be a good value. But what is most relevant is not the level to which it must be reached, but how it must be reached”, says Barata.

Currently, storage is at 18.81% of capacity in the subsystem. According to the specialist, in addition to rainfall, it is necessary to establish a strategy for reaching this level, based on the use of another energy source. Currently, the ONS has been using thermoelectric plants, preferably those powered by gas, for this purpose.

“The recomposition of the reservoirs in October and November was exceptional, there is no guarantee that we will have a generous summer, as was the case in spring. If we use thermal plants, we will have two problems: they contribute to the emission of greenhouse gases and they provide a bill that we will not be able to pay, with higher costs and tariffs. It is something that has to be planned for, in the future, to be produced by renewable energies”, concludes the specialist.

In the last weekly bulletin released by the operator, it was found that the rainy season this year happened at the most frequent time, in October. Unlike last year, when the rains began to fall in earnest only in December, which helped to aggravate the water crisis.

However, even if the reservoirs reach levels considered ideal, the ONS reinforced that the thermal plants will not cease to be activated, since this is the only mode of energy generation that does not depend on climatic factors for its operation. The new scenario, however, would allow the use of hydroelectric plants at full capacity, since there would no longer be a need to save water.

With the need to activate thermoelectric plants as a result of the water crisis, consumers’ electricity bills became more expensive, with two increases in the tariff flag. In late September, the National Electric Energy Agency (Aneel) created the water scarcity banner, with a rate of R$ 14.20 per 100 kWh (kilowatt-hour). An increase of 66% compared to the level two red flag, which was in force until then (R$9.49).

Although they act to offset the losses caused by the reduction of generation from hydraulic sources, thermoelectric plants have never become the main energy matrix in the country. This post is still led by hydroelectricity.