Brazil's National Electric Energy Agency (ANEEL) has put out for public consultation the draft tender notice for Transmission Auction No. 01/2027, which, for the first time, includes a lot dedicated to battery energy storage within the transmission segment of the National Interconnected System (SIN). Public Consultation No. 032/2026 will receive contributions from September 10 to October 26, 2026, and the auction is scheduled for April 30, 2027, at B3 in São Paulo. The agency estimates investments of R$ 12.9 billion and the creation of 29,500 direct and indirect jobs.
A broad auction, with 12 lots in 13 states
The initial version of the tender notice comprises 12 lots totaling 3,245 km of new transmission lines and 1,386 MVA of transformation capacity. The works are spread across Acre, Alagoas, Bahia, Ceará, Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Pará, Piauí, Rio Grande do Norte, Rio Grande do Sul and São Paulo. Winners will have 36 to 60 months from contract signing to complete the projects.
The Northeast carries significant weight in the auction design:
- Lots 9 and 12 (CE/RN): aimed at serving energy-intensive loads in the region, in coordination with the National Transmission System Access Policy (PNAST). Lot 9 includes 500 kV lines between Açu III and Pecém IV and the new Pecém IV substation. Lot 12 depends on confirmation of the access volume by November 16 and will only be offered if Lot 9 receives a valid bid.
- Lot 7 (BA/PI): four independent sublots of synchronous condensers at 500 kV substations, competed under a cross methodology, in which ANEEL compares the lowest bid for the entire lot with the sum of the lowest bids per sublot.
- Lot 2 (AL): 230 kV line between Messias and Arapiraca III.
Lot 5: the first transmission battery in the SIN
The point of greatest interest for the storage market is Lot 5, which provides for an energy storage system (SAE) at the 230/69 kV Cruzeiro do Sul substation, in Acre, with 100 MW and 200 MWh, connected to the 69 kV sector and using grid-forming technology. The goal is to improve the reliability of supply to Cruzeiro do Sul and Feijó, a region also covered by Lot 4, with new 230 kV lines.
Grid-forming inverters can establish a voltage and frequency reference for the grid, rather than merely following an existing signal, a valuable feature in weaker systems or at the edges of the grid. The ratio of 200 MWh to 100 MW indicates a system with two hours of duration at rated power.
Another particularity lies in the contract: while the other lots will have 30-year concessions, Lot 5 will have a term of 18 years, due to the useful life of the batteries. The construction period is 36 months, the shortest in the auction.
Next steps for the tender notice
Once the consultation closes, ANEEL will analyze the contributions and submit the tender notice for prior deliberation by its Board of Directors. If approved, the text goes to the Federal Court of Accounts (Tribunal de Contas da União) in December. The inclusion of Lot 11, linked to the Brazil-Bolivia interconnection, still depends on definitions in the Concession Plan and on requirements of the international agreement.
What changes in practice for the BESS market
For developers, EPCs, manufacturers and battery suppliers, Lot 5 sets a precedent: storage starts to be treated as a transmission asset, remunerated under a long-term contract, and not merely as a complement to power plants. Some points deserve attention:
- Public consultation as an opportunity: until October 26, companies can suggest adjustments to the lot's technical requirements, performance criteria and contractual obligations.
- Grid-forming requirement: suppliers of power conversion systems will need to demonstrate this capability, which may filter out participants.
- Life cycle and degradation: the 18-year contract requires a clear strategy for warranties, capacity augmentation over time, and operation and maintenance.
- Tight schedule: 36 months for delivery in a remote region calls for well-defined logistics planning and supply chain from the bid stage.
Although located in Acre, the lot serves as a regulatory benchmark for future transmission storage projects across the country, including in the Northeast, where grid expansion for energy-intensive loads remains on the agency's radar.
Original source: ANEEL — Leilão marcado para abril de 2027, o primeiro com contratação de baterias na transmissão, entra em consulta pública