Our energy is fundamentally hydroelectric, and that makes us vulnerable.
Após sete meses de sobretaxa emergencial provocada pela pior seca em quase um século, o Brasil encerra abril de 2022 com a bandeira tarifária verde — um sinal de que os reservatórios do Sudeste e Centro-Oeste recuperaram fôlego suficiente para sustentar o país até o fim do ano. O Operador Nacional do Sistema Elétrico anuncia que as usinas termelétricas voltarão a operar apenas em sua capacidade mínima, aliviando uma matriz energética que depende, em sua essência, da chuva. O alívio é real, mas parcial: as tarifas não cairão, e a estabilidade prometida ainda guarda a incerteza de um inverno cujos padrões de precipitação já não são o que eram.
- A bandeira de escassez hídrica, que adicionava R$14,20 a cada 100 kWh consumidos, pesou nas contas de brasileiros por sete meses consecutivos — reflexo direto da pior seca em 91 anos.
- Com reservatórios do Sudeste e Centro-Oeste nos melhores níveis desde 2012, o ONS declara o fim da emergência e projeta estabilidade tarifária até dezembro de 2022.
- A transição para a bandeira verde não significa contas mais baratas: os reajustes tarifários adiados pelas distribuidoras durante a crise serão reincorporados como correção inflacionária.
- As termelétricas, que chegaram a operar acima de 20.000 MW durante o pico da crise, retornam ao mínimo inflexível de cerca de 4.000 MW — um desafogo significativo para o sistema.
- Especialistas alertam que o período seco a partir de maio exige gestão cuidadosa dos reservatórios, pois padrões de chuva mais erráticos tornam a estabilidade frágil e condicional.
Em meados de abril de 2022, o Operador Nacional do Sistema Elétrico anunciou que a bandeira tarifária verde vigoraria até o fim do ano — encerrando a sobretaxa de escassez hídrica que havia sido imposta em setembro de 2021 após a pior seca em quase um século. Durante sete meses, consumidores e empresas pagaram R$14,20 extras a cada 100 kWh consumidos. Com os reservatórios do Sudeste e Centro-Oeste nos melhores níveis desde 2012, o ONS avaliou que o país poderia atravessar 2022 sem recorrer ao regime de emergência.
O sistema de bandeiras tarifárias existe para traduzir o custo real da geração elétrica na conta do consumidor. Quando os reservatórios secam, as usinas termelétricas — muito mais caras de operar — precisam compensar o déficit. O Brasil depende das hidrelétricas para cerca de 65% de sua geração, o que torna a matriz energética estruturalmente vulnerável à falta de chuva. Em 2021, as termelétricas chegaram a operar com mais de 20.000 MW de capacidade; agora, retornariam ao mínimo inflexível de aproximadamente 4.000 MW.
O economista Roberto Kishinami, do Instituto Clima e Sociedade, temperou o otimismo com cautela. O alívio imediato não apareceria na próxima fatura — o período de medição já havia encerrado — e os reajustes tarifários adiados pelas distribuidoras seriam reincorporados como correção inflacionária de rotina. A bandeira verde elimina a sobretaxa emergencial, mas não reduz as tarifas. Kishinami também questionou se a bandeira de escassez não havia permanecido ativa por mais tempo do que as condições exigiam, e alertou para a necessidade de usar a água com parcimônia diante de um inverno de padrões pluviométricos cada vez menos previsíveis.
O diretor-geral do ONS defendeu como prudente a contratação de capacidade termelétrica emergencial até dezembro de 2025, um colchão de segurança para o médio prazo. A energia eólica, que já responde por cerca de 9% da geração nacional, avança como fator de diversificação. Mas o país permanece, em sua essência, dependente da chuva. A bandeira verde sinalizava que a crise imediata havia passado — e que sua continuidade dependia, como sempre, do que o céu decidisse fazer.
Brazil's grid operator announced in mid-April 2022 that electricity bills would carry the green tariff flag through the end of the year, a shift that meant households and businesses would stop paying the emergency surcharge that had been tacked onto every kilowatt-hour since September. The water scarcity flag, which added R$14.20 to every 100 kWh consumed, had lasted seven months—a response to 2021's worst drought in nearly a century. Now, with reservoirs recovering across the Southeast and Center-West regions to their healthiest levels since 2012, the National Electric System Operator (ONS) expected stability to hold through December.
The tariff flag system is the mechanism that translates the real cost of generating electricity into what consumers pay. When hydroelectric dams run low and thermal power plants must be fired up to fill the gap, those plants are expensive to operate. The surcharge exists to cover that difference and, in theory, to discourage consumption during tight periods. Brazil's energy matrix depends heavily on water—hydroelectric plants account for roughly 65 percent of the country's generation—which makes the system vulnerable to drought. When rain fails, costs spike, and bills follow.
Roberto Kishinami, a senior coordinator at the Climate and Society Institute, offered a cautious reading of the news. The immediate relief consumers might expect would not materialize on their next bill, he explained, because the measurement period for that invoice had already closed. What would happen instead was a rebalancing: the tariff increases that major distribution companies had deferred during the scarcity period would be reapplied as part of routine inflation adjustments. The green flag meant no additional emergency surcharge, but it did not mean rates would fall. "The tariff flag exists to advance cash flow for distribution companies so they can absorb higher generation costs," Kishinami noted. "That's necessary because our energy is fundamentally hydroelectric."
He also pushed back against the duration of the scarcity flag itself, suggesting it had remained in place longer than conditions warranted. The dry season beginning in May carried uncertainty, he said, because rainfall patterns had shifted in recent years. A drier-than-normal winter would not necessarily force the grid to rely on thermal plants, but it would require careful management of reservoir levels. "We need to use water sparingly," he said.
The 2021 drought had been severe enough to justify emergency measures. For months, thermal generators had run at more than 20,000 megawatts of capacity to compensate for depleted dams. The ONS director-general, Ciocchi, noted that the grid would now rely on thermal plants only at their inflexible minimum—roughly 4,000 megawatts of plants that cannot be shut down. The improvement in reservoir levels meant the country could move through 2022 with far less strain than it had endured the year before. The government had also contracted emergency thermal capacity through December 2025 as a longer-term buffer, a decision Ciocchi defended as prudent.
Brazil's energy mix has been diversifying. Wind power now accounts for about 9 percent of generation, a growing share that reduces dependence on hydroelectric alone. But for now, the grid remained fundamentally tied to rainfall. The green flag signaled that the immediate crisis had passed, that reservoirs had refilled enough to sustain the country through the rest of the year without the emergency tax on consumption. Whether that stability would hold depended on whether the rains came as expected—and on how much water the dry season would demand.
Notable Quotes
The tariff flag exists to advance cash flow for distribution companies so they can absorb higher generation costs. That's necessary because our energy is fundamentally hydroelectric.— Roberto Kishinami, Climate and Society Institute
The scarcity flag lasted longer than necessary. Once reservoir levels recovered, the emergency conditions no longer existed.— Roberto Kishinami, Climate and Society Institute
The Hearth Conversation Another angle on the story
Why does Brazil's electricity system depend so heavily on what happens with rainfall?
Because roughly two-thirds of the country's power comes from hydroelectric dams. When it rains, water fills the reservoirs and the dams generate cheap electricity. When it doesn't rain for months, the dams run low and the grid has to switch on thermal plants, which burn fuel and cost far more to operate.
So the tariff flag is basically a way to pass that cost shock directly to consumers?
It's more subtle than that. The flag is meant to signal the real cost and discourage wasteful consumption during tight periods. But yes, when thermal plants are running, someone has to pay for the fuel. The surcharge helps distribution companies cover those costs without going bankrupt.
The expert said the scarcity flag lasted longer than necessary. What did he mean?
He was saying that by the time it was lifted, reservoir levels had already recovered enough that the emergency conditions no longer existed. The flag had served its purpose—it had bought time and cash flow for the system to stabilize—but keeping it on after that point was extracting money from consumers for a crisis that had already passed.
If the green flag means no surcharge, why would bills stay high?
Because the distribution companies had deferred normal inflation adjustments while the scarcity flag was in place. Now those adjustments come back. You're not paying the emergency tax anymore, but you're paying the routine cost-of-living increase that would have happened anyway. It's a wash for consumers, more or less.
What happens if it doesn't rain enough this winter?
That's the uncertainty. The dry season starts in May, and rainfall patterns have become less predictable. If it's drier than normal, the grid might need to run more thermal plants. But the expert said that doesn't automatically mean another surcharge—it depends on how carefully they manage the water they have.
So this green flag is really just a reprieve, not a solution?
It's a reprieve built on the assumption that the rains will cooperate. The real solution is diversifying away from hydroelectric dependence—wind is growing, but it's still only about 9 percent of the mix. For now, Brazil is betting on normal weather.