Hybrid barriers combine physical and chemical elements, leading to the improvement of Brazilian water resource management and the effectiveness in containing invasive species.
Currently, Brazil has over 700 hydropower plants, covering approximately 80% of the national territory, which is encompassed by hydrographic basins. Among these installations, the largest ones are predominantly located in the Northern region of the country.
The energy produced by Brazilian hydropower plants represents the main source of energy supply for the country. In 2022, they played a significant role, accounting for 67% of the country's total electricity generation. In other words, for every 100 kWh of electricity generated in Brazilian territory, 67 kWh came from hydropower sources.
Challenges and Impacts of Hydropower Generation
🌿 Biodiversity loss
🌊 Flooding of inhabited areas
🐟 Alterations in the aquatic ecosystem
💧 Hydrological risks
The Threat of Golden Mussels to Brazilian Hydropower Plants
In addition to the previously mentioned concerns, a new adversity of animal origin emerges, focused on a mollusk with the potential to cause substantial damage. The golden mussel (Limnoperna fortunei), originating from Southeast Asia, is an invasive mollusk species that poses a serious threat to the Brazilian environment and economy. Its arrival in Brazil, in 1998, through ballast water of cargo ships, triggered a rapid and alarming spread of this species throughout the country.
"Currently, this mollusk has expanded its range, reaching the north, up to the Pantanal (along the Paraguay River), the states of São Paulo and Minas Gerais, covering a distance of 3,000 km from its initial entry point. Due to this extensive invasion, South America has become the region where Limnoperna fortunei is most widely distributed" (Sanson 2018).
This threat translates into the interruption of turbine operations at hydropower plants, as well as the obstruction of pipelines. This mainly occurs due to the remarkable ability of these mussels to adhere to surfaces and reproduce prolifically.
As can be seen in the images below:
Proliferation of Golden Mussels (Limnoperna fortunei) in Brazil between the years 1990, 2005, and 2023. Source: Collaborative database on biological invasions.
The impacts caused by the species are multiple:
Structural damage to hydropower facilities
Machine shutdowns
Loss of generation and revenue
High costs associated with cleaning and consumables (chlorine) for recurring cleaning or discharge.
High velocities prematurely wear out the cooling system.
Golden mussels at the Sobradinho power plant (BA) Photo: Credit: Cbei/divulgation
Hybrid Barriers: Effective Combat Against Golden Mussel Invasion
Hybrid barriers can be defined as a strategy for controlling the invasion of golden mussels in hydropower equipment. By combining physical and chemical elements in an integrated approach, they are specifically designed to prevent mussels from accessing plant facilities.
The physical elements of hybrid barriers comprise:
Nets, screens, or similar devices acting as a physical barrier, obstructing mussels' access to plant surfaces. On the other hand, the chemical elements incorporated into hybrid barriers consist of:
Growth inhibitors, killers, Tinopal-Fen-Et-7 (phenolic compound that prevents mussel shell formation), and Biofouling Shield (organic compound that prevents mussel attachment to surfaces).
Other examples of chemicals used for this purpose include:
Sodium hydroxide (NaOH): Strong alkali that dissolves mussel shells.
Copper sulfate (CuSO₄): Copper salt that kills mussels.
Sodium hypochlorite (NaOCl): Oxidizing agent that kills mussels.
Advantages and Disadvantages of Using Hybrid Barriers:
Advantages:
Enhanced effectiveness
Adaptive flexibility
Diversified applications
Disadvantages:
High cost
Maintenance complexity
Chemical Barriers:
Toxicity to fish and other aquatic organisms
Degradation of water quality
Impact on biodiversity
Commitment to Ongoing Research and Development
The goal of new research on hybrid barriers in Brazil is to further enhance the efficiency and effectiveness of these solutions while working to reduce the costs associated with their implementation and maintenance and impacts on biodiversity.
Continued investment in scientific and technological advancements is essential to further improve this technology, reduce costs, and expand its use across Brazil's hydropower sector. Only then can we ensure the integrity of plants, environmental preservation, and long-term sustainability of Brazilian hydropower operations.