The Ministry of Mines and Energy’s National Energy Plan (PNE 2050) has cast increased power generation from hydroelectric plants as a priority. The goal is to grow installed capacity from 98 GW to 168 GW by the end of 2030, and the target is river basins in northern Brazil.
It is the next episode in an old soap-opera whose outcome is usually tragic. The Balbina dam built on the Uatumã River in the Amazon in the 1980s is one of many examples.
In a study published in 2021, researcher Thiago B.A. Couto, together with the National Geographic Society and Florida International University’s Environmental Institute, showed that small hydroelectric dams in the Amazon cause the loss of river connectivity and prevent migratory fish from completing their life cycles.
“Indigenous groups and riverbank communities depend on being able to fish migratory species for their livelihood,” wrote Couto. “Nine small hydroelectric dams on the Juruena River, a tributary of the Tapajós in Mato Grosso, already affect several peoples, such as the Enawenê-Nawê.”
This is an important warning, as small plants make up 80% of the total 275 hydroelectric plants installed in the Amazon. Their licensing is less bureaucratic and they are less subject to the usual controversies that large undertakings face.
Belo Monte, on the Rio Xingu, has become an icon of the last decade. Located near the city of Vitória do Xingu, near Altamira, after just a few years of operation the dam has become more famous for its environmental and social liabilities than for the energy it generates, even though it has adopted the run-of-the-river model. In it, the turbines lie horizontally at the bottom of the river, the reservoir area is reduced, and the volume of water that enters the plant is practically the same as the volume that leaves. From an environmental point of view, it has less impact.
“The problem with this model is that it doesn’t protect water enough. It remains very vulnerable to heavy droughts, which happened in 2021,” argues Jansen Zuanon. “So there will be more pressure for new reservoir projects or reservoirs in series, like we have on the Tapajós.”
To make things worse, climate models are pointing to changes in rain patterns, with less rain in the eastern part of the Amazon which is exactly where Belo Monte is located. Zuanon warns that in order to maintain minimum turbine function, more water will have to be diverted from Volta Grande, the highly scenic region flooded by the dam.
A survey carried out by the Instituto Socioambiental together with the Juruna people evaluated the recent hydrological cycle of the Xingu and found, among other factors, a drop in fruit production on the plants in the local igapós, or flooded forests. This resulted in less food for turtles and tambaquis, meaning less food for the people living there.
“For the indigenous people, the question is basic: if there is no more food for the fish, there will be no more fish to eat,” says biologist Camila Cherem Ribas from INPA’s Board of Biodiversity and Scientific Biological Collections Program.
Madeira river is another giant facing the threat of hydroelectric dams. The huge Jirau and Santo Antônio dams have been operating near Porto Velho in the state of Rondônia since the last decade, and two new hydroelectric plants are included in the 2050 PNE as part of binational agreements with Bolivia.
According to the Dam Environmental Vulnerability Index (DEVI), developed by geologist Edgardo Latrubesse and other authors, the Madeira is named the most vulnerable river in the Amazon. And a study by Latrubesse published in Nature in 2020 points out that a total of 16 hydroelectric projects threaten the upper Madeira.