Frederico Boschin

Energy transmission is one of the invisible—but absolutely essential—pillars of the energy transition. In this column, we've already addressed the operational challenges of energy distribution and generation and the bottlenecks in integrating intermittent renewable sources countless times. Imagine the electricity sector as a soccer team, where each of the sources (solar, wind, hydro, biomass, and thermal), spread across different parts of the field, with different functions (energy attributes), needs to organize and actively interact. This would be the tactical scheme, some more conservative (hydrothermal), others more daring (renewable). Without a robust and well-coordinated transmission network, this game doesn't develop, and energy doesn't reach the right audience—or rather, the homes, industries, and cities that need it. In an energy transition scenario, transmission is crucial, precisely because many solar and wind plants are located in remote areas, far from major consumption centers. Transmission, therefore, allows for the proper integration of these sources and transports this clean energy to where it's needed. Furthermore, a well-planned and structured grid helps balance supply and demand (balancing system safety and stability criteria), avoiding blackouts and energy waste (known as curtailment). This is even more important with intermittent sources such as solar and wind. Without transmission capacity, many renewable energy projects are shelved. This is currently a major problem for our National Interconnected System (SIN). In Brazil, this issue is especially relevant: approximately 90% of the territory is already interconnected to the National Interconnected System (SIN), one of the largest transmission networks in the world. This places the country in a strategic position to lead a fair, safe, and inclusive energy transition. The regulatory framework for curtailment is provided by REN. ANEEL 1.030/2022, which established three conditions for restricting generation: External unavailability, such as bottlenecks caused by the Basic Grid and Other Transmission Facilities (DITs); Compliance with electrical reliability requirements, such as preserving the transmission grid; and Energy Ratio, in the scenario of a mismatch between supply and demand. In 2025, the curtailment problem in Brazil continued to grow, reflecting the mismatch between the accelerated expansion of renewable sources and the electrical infrastructure available to integrate them into the system. According to ePowerBay, more than 129 GWh of solar energy was wasted in January 2025 alone, concentrated in substations such as Janaúba 3 (77,5 GWh), Jaíba (31,9 GWh), and Sol do Sertão (20 GWh) — all in Minas Gerais. To solve this problem, countries are investing in planning and new technologies, primarily aimed at efficiency and loss reduction. Modern, well-planned lines reduce energy losses along the way, making the system more efficient and sustainable. Speaking of new technologies, two emblematic examples of ultra-high-voltage transmission infrastructure are shaping the global energy transition. In China, networks with UHV (Ultra-High Voltage) technology are now widely implemented within the context of a national "super grid," notably the Changji–Guquan line, which holds the world record: transmitting 12 GW of direct current (UHVDC) power at 1.100 kV over a distance of 3.293 km. These lines connect remote regions rich in renewable energy (such as the northwest) to large urban centers in the east of the country. The Chinese grid already has 31 UHV lines in operation, combining alternating current (UHVAC) and direct current (UHVDC) technologies, enabling massive integration of renewable sources and significantly reducing transmission losses. In Germany, the SuedLink Project is one of the largest underground direct current transmission projects in Europe. With a length of 580 km and a capacity of 2 GW, it connects northern Germany (where there is significant wind generation) to the industrialized south, where demand is highest. It uses ±525 kV HVDC technology with high-capacity copper cables and XLPE insulation, ensuring efficiency and reliability. In addition to reducing losses, SuedLink is essential for integrating more renewable energy into the German grid and meeting climate targets. This makes it clearer that transmission infrastructure plays a crucial role in the global journey toward decarbonization and achieving clean energy goals, whether through increased investment or greater planning in the process of integrating renewable sources.