When Abundance Becomes a Problem: Brazil’s Renewable Dilemma

In the sun-drenched landscapes of Brazil’s Northeast, a quiet crisis is unfolding. While the country has successfully staged a green energy revolution, with solar power leaping from a mere 1% of the grid in 2019 to 20% today, it is now a victim of its own success. Brazil is producing more clean energy than its ageing wires can carry, leading to a staggering 6 billion reais in wasted power last year alone.

The phenomenon, known in the industry as "curtailment," saw nearly 20% of all wind and solar generation simply discarded in 2025. At high noon, when the Brazilian sun is at its zenith, solar panels provide up to 44% of the nation’s electricity. But when the grid reaches its physical limit, the National System Operator (ONS) is forced to "unplug" professional plants to prevent a catastrophic overload.

"Generation cutting is our greatest challenge today," says Rui Altieri, president of Apine, the association of independent power producers. The economic fallout is already visible: over 500 renewable energy projects were abandoned last year as investors baulked at the prospect of building plants only to be told to switch them off during their most productive hours.

The ‘Rewinding’ Dam

To solve this, Brazil is looking at two competing technologies to "store the sun" for the evening peak. The first is a centuries-old concept with a modern twist: Pumped Storage Hydropower (PSH), or what locals are calling "rewinding" dams.

The mechanics are elegantly simple. During the day, when solar energy is in surplus and prices are at their lowest, the excess electricity is used to pump water from a lower reservoir to an upper one. When the sun sets and demand spikes, the water is released back down through turbines to generate power.

Those plantas literally rewinds. The fuel is produced by the sun during the day, stored as water, and returned when the system needs it.

Despite being the world’s second-largest hydroelectric producer, Brazil currently has zero pumped storage plants. Meanwhile, China, the US, and Japan have made them the backbone of their grids. The Brazilian utility Copel is now planning the country’s first: a 70MW facility in Paraná capable of powering a city of 200,000 people. Proponents argue these "water batteries" can last for a century, far outliving chemical alternatives.

The Rise of the Mega-Battery

However, the "rewinding" dams face a formidable new rival: lithium-ion mega-batteries. Known as Battery Energy Storage Systems (BESS), these warehouses full of cells — identical to those found in electric cars — are seeing a global explosion in adoption.

The numbers are stark. Between 2023 and 2025, the price of stationary lithium batteries plummeted by 55%. For the first time, the cost per kilowatt-hour of a battery system has dropped below that of a typical pumped hydro plant. Furthermore, a battery farm can be built in months, whereas a dam takes years.

In 2025, global battery capacity officially overtook pumped hydro. The Brazilian government appears to be leaning toward this faster fix, with its first "capacity reserve auction" scheduled for April, specifically targeting large-scale battery storage.

A Systemic Struggle

The transition is not without friction. Energy producers are currently locked in a legislative battle with the government over who should foot the bill for these storage solutions. Under current rules, the cost of the upcoming battery auctions falls entirely on the generators, a burden they argue is unfair for a service that benefits the entire national grid.

"This is a systemic service," says Josiani Napolitano, Apine’s director of institutional relations. "We are contributing technically to building a more balanced solution."

Whether the future belongs to the longevity of the "rewinding" dam or the rapid deployment of the mega-battery, one thing is certain: Brazil’s green energy gold rush is being replaced by a complex, high-stakes race to build the "bottles" for its sunshine.

A R$17 Billion Answer to Renewable Waste

Seeking an answer to the challenge of wasted solar energy, Brazil intends to conduct an auction for a large power transmission project which will utilize new technology to transmit renewable energy from the Northeast region to the Southern part of Brazil. 

The project which costs approximately R$17 billion aims to establish the Northeast Bipole Express Corridor 2, which will decrease wind and solar power curtailment. The line will extend from Angicos in Rio Grande do Norte to the city of Itaporanga in Paraná, which will establish it as one of Brazil's most costly transmission projects.

The Energy Research Company EPE has completed its studies and viability by late 2025. Now, the project to enter the auction process by 2027. The project aims to enhance the Northeast capacity for renewable energy exports which exists as the prime renewable energy potential area in Brazil but faces maximum generation limitation problems. The 2025 wind and solar power generation resulted in 20 percent of electricity being wasted, which caused a revenue loss of R$6.5 billion.

The project will develop new electricity import capabilities for the South, which will assist in maintaining power distribution across different regions. The system will operate through a high-voltage direct current HVDC bipole system which employs Voltage Source Converter VSC technology to deliver superior performance across extended distances and intermittent renewable energy sources. 

The total investment, which includes grid upgrades, will reach R$25 billion. The auction currently appears controlled by China State Grid as the leading contender, although AXIA Energia and other companies will also take part in the bidding process.