The ANA assessed that Light‘s alternative proposal for the Lajes Complex meets water requirements, yet brings greater operational vulnerability than the Bypass Tunnel.
The National Water and Basic Sanitation Agency (ANA) has issued a conditional favorable opinion on the alternative project submitted by Light to ensure water security at the Lajes Complex in the interior of Rio de Janeiro.
The proposal aims to replace the construction of the Bypass Tunnel—a project currently stalled at just 27% completion—with infrastructure integrated into the expansion of the Fontes Nova hydroelectric power plant.
Although the regulatory agency considers the arrangement viable under current rules, it warned of increased operational risks and conditioned implementation on the adoption of strict mitigation measures.
Project deadlock and the utility’s new alternative
The discussion involves balancing clean energy generation with water supply for the Metropolitan Region of Rio de Janeiro, which depends on the flow directed to the Guandu System.
The original Bypass Tunnel project planned to transport 120 m³/s of water by gravity between the Vigário and Ponte Coberta reservoirs, allowing the Nilo Peçanha plant to be shut down for maintenance without affecting water supply.
With work halted due to contractual conflicts, Light suggested expanding Fontes Nova‘s capacity from the current 132 MW to about 292 MW, creating a new pipeline capable of conveying 68 m³/s of water.
Technical vulnerability and regulatory requirements
In an analysis sent to the National Electric Energy Agency (Aneel), ANA stressed that the alternative solution requires the simultaneous operation of different structures to achieve the necessary flow rate.
“The proposed alternative has not yet conclusively demonstrated functional equivalence compared to the project originally planned for the transposition tunnel,” noted the case rapporteur at the energy agency.
Should an electromechanical outage occur at Fontes Nova or the Lajes SHP, the volume transported could fall short of the operational requirements at the Ponte Coberta reservoir and the Pereira Passos plant.
To mitigate failures, ANA determined that the Lajes reservoir must be maintained as a strategic reserve, to be activated only in emergencies with prior authorization and coordination with the ONS.
Next steps and final decision
The decision on whether to accept the replacement of the Bypass Tunnel with the expansion of the generating park rests with Aneel‘s board of directors and the granting authority, and also depends on environmental licensing from Inea.
Resolving this deadlock is crucial to ensuring the continuity of investments in sustainable infrastructure and maintaining the reliability of water and energy supplies in the state of Rio de Janeiro.
