Thermal power plants play a fundamental role in Brazil’s energy matrix, especially in critical moments of water scarcity. While the country has historically relied on hydroelectric energy, the vulnerability caused by droughts has highlighted the importance of thermal power plants as an energy security alternative. But what exactly are these plants, where do their energy sources come from, and what is the environmental impact of this type of electricity generation?
What are thermal power plants?
Thermal power plants are facilities that generate electricity by burning fuels such as natural gas, coal, fuel oil, biomass, or even urban waste. The basic process involves burning fuel to generate heat, which, in turn, heats water in boilers to produce steam. This steam drives turbines connected to generators, converting thermal energy into electrical energy.
Unlike hydroelectric plants, which depend on water flow to generate energy, thermal power plants can operate regardless of specific weather conditions, making them a strategic energy source, especially during drought periods when reservoir levels are low.
Energy sources for thermal power plants
In Brazil, the main energy sources for thermal power plants are:
- Natural gas: Accounts for about 25% of the national energy matrix and is the main source used in thermal power plants. Brazil has large natural gas reserves, especially in the pre-salt layer.
- Coal: Although Brazil does not have large reserves of high-quality coal, some thermal power plants still use this fuel, mainly in the southern part of the country.
- Fuel oil: A costly and polluting source, primarily used in emergency situations.
- Biomass: Brazil is a large producer of biomass, especially from sugarcane bagasse, and this renewable source is gaining space in thermal power plants.
- Solid waste: Some plants are starting to explore the combustion of solid waste, such as urban garbage, for electricity generation, which also helps solve waste disposal problems.
Are thermal power plants a clean energy source?
No. Thermal power plants, in general, are not considered clean energy sources. Most of them emit large amounts of greenhouse gases (GHG), such as carbon dioxide (CO2), into the atmosphere, especially those that use coal and fuel oil. In terms of environmental impact, they are more polluting than hydroelectric and renewable sources like solar and wind power.
Plants powered by natural gas, for example, emit fewer pollutants than coal, but they still contribute to global warming. On the other hand, thermal power plants that use biomass can be considered more sustainable since the carbon cycle of biomass tends to be neutral, meaning the amount of CO2 emitted during combustion is offset by the CO2 absorbed by the plant during its growth.
The thermal power plant market in Brazil
The participation of thermal power plants in Brazil’s electric matrix has been growing. According to the Ministry of Mines and Energy (MME), in 2023, thermal power plants accounted for about 25% of the energy generated in Brazil. This marks a significant increase compared to previous years, when hydroelectric plants dominated almost 80% of electricity generation.
With the increased demand for electricity and the need to diversify the energy matrix, the Brazilian government has encouraged the use of natural gas and biomass as less polluting alternatives to coal and fuel oil. The energy auction held in 2023 also prioritized thermal power plant projects using gas and biomass, highlighting the move to make the matrix more diversified and less dependent on intermittent sources like wind and solar.
Thermal power plants in times of water crises
Thermal power plants become especially important during water crises. In 2021, Brazil faced one of the worst water crises in nearly a century, forcing the government to activate a series of thermal power plants to ensure energy supply. This measure, however, comes at a high cost. On average, the energy generated by thermal power plants is more expensive than hydroelectric, solar, or wind power. During the 2021 crisis, activating these plants was one of the factors that drove up electricity tariffs in the country, leading to the implementation of the red tariff flag.
According to data from the Chamber of Electricity Commercialization (CCEE), the activation of thermal power plants in 2021 increased by 79% compared to the previous year. By 2023, with less dependence on hydroelectric plants, thermal energy remained in operation during the dry season but with more balanced planning to avoid cost spikes.
Future prospects
The trend for the coming years is that Brazil will continue to rely on thermal power plants as “backup energy” during water crises. However, energy policies are focused on expanding renewable sources such as solar and wind, which, together with thermal power plants, form a safer and more flexible energy system.
The construction of new thermal power plants, especially those powered by natural gas and biomass, is part of the energy matrix expansion plan until 2030, according to the Ten-Year Energy Plan (PDE 2030). However, experts warn that it is essential to balance the expansion of thermal power plants with a commitment to reducing greenhouse gas emissions and meeting the climate targets of the Paris Agreement.
Conclusion
Thermal power plants are a key component of Brazil’s energy matrix, providing a reliable and essential energy source during water crises. However, the country faces the challenge of balancing the use of these plants with the need to reduce emissions and increase the participation of renewable sources in the matrix. With proper planning, thermal power plants will continue to play their role as “energy security,” while Brazil advances toward a more sustainable future that is less dependent on fossil fuels.
