by Siemens Energy
Gás Natural Açu (GNA) flexible combined-cycle power plants enable the integration of renewables, ensuring grid stability, and sustainable growth.
Brazil’s energy transition is accelerating, driven by a growing share of renewable energy. As intermittency increases, flexible gas-fired power plants - based on advanced gas and steam turbine technology in a combined cycle power plant - play a critical role in ensuring grid stability and energy security while supporting sustainable growth.
Brazil’s expanding renewable energy capacity creates new challenges for grid reliability. Variability in wind, solar, and hydropower requires flexible, dispatchable generation to balance supply and demand.
Gas-fired power plants provide this flexibility. By delivering firm power when renewable output fluctuates, they stabilize the system and enable further expansion of clean energy sources.
At the Port of Açu in Rio de Janeiro, the GNA (Gás Natural Açu) complex was developed to meet this need - combining high-efficiency gas-fired power generation with the operational flexibility required for Brazil’s evolving energy system.
The GNA project, developed by a consortium including BP, Siemens Energy, Prumo, SPIC, and Siemens Financial Services, represents an investment of approximately €1 billion.
As one of the largest gas and energy hubs in Latin America, the complex integrates two gas-fired power plants with a dedicated LNG terminal. A floating storage and regasification unit (FSRU) supplies up to 21 million cubic meters of natural gas per day, ensuring reliable fuel availability.
Connected to the National Interconnected System (SIN), GNA strengthens Brazil’s energy infrastructure and supports the continued growth of renewable energy.
Commissioned in 2021, GNA I provides 1.3 GW of flexible power generation - enough to supply approximately 6 million households.
The plant operates with three Siemens Energy SGT-8000H gas turbines and one SST6-5000 HI 50 steam turbine in a combined cycle configuration. Heat recovery enables the plant to generate around an additional 33% additional of electricity without extra fuel, significantly improving efficiency.
Its full operational flexibility allows rapid response to grid demand, making it essential for maintaining stability in a renewable-heavy energy system.
Operational since 2025, GNA II is the largest and most efficient gas-fired power plant in Brazil. With an installed capacity of 1.7 GW, it can supply electricity to around 8 million homes.
Using advanced HL-class gas turbines, the plant achieves efficiency levels above 60%, placing it among the top-performing facilities globally. Around 40% of its output continuously feeds the national grid, reinforcing system reliability.
Combined, GNA I and GNA II can supply power to up to 14 million households, significantly enhancing energy security in Brazil.
The complex is designed for expansion. With 3.4 GW installed and a licensed capacity of up to 6.4 GW, it is set to become the largest gas-fired energy hub in Latin America.
Plans include the potential integration of onshore gas pipelines to connect the complex to Brazil’s existing network, further strengthening energy infrastructure.
3.4 GW
of electrical power output at the largest gas-fired energy hub in Latin America.
14 million
households powered by GNA
Siemens Energy plays a central role as an energy technology provider and long-term partner. The company supplies key components for the power island, including gas turbines, steam turbines, generators, heat recovery steam generators, and instrumentation and control systems.
Through long-term service agreements, Siemens Energy also ensures reliable plant operation with advanced remote monitoring and diagnostics from its global Remote Operations Center.
The GNA complex shows how gas-fired power plants can support renewable energy integration while ensuring grid stability and energy security.
By combining flexible generation, high efficiency, and future-ready design, GNA enables sustainable growth and strengthens Brazil’s path toward a resilient energy system.