'A bullet train for power': China's ultra-high-voltage electricity grid

The "Bullet Train for Power": China's Ultra-High-Voltage Grid Revolution

In the global quest to combat climate change and transition to renewable energy, China is pioneering an engineering marvel: the ultra-high-voltage (UHV) electricity grid. This vast network, likened to a "bullet train for power," is revolutionizing long-distance energy transmission, enabling efficient delivery of clean energy from remote regions to urban and industrial centers.

Understanding UHV: A Technological Leap

UHV transmission lines operate at extremely high voltages—800 kilovolts (kV) or above for direct current (DC) systems and 1,000 kV or above for alternating current (AC) systems. The principle is simple yet transformative: higher voltage levels reduce current, minimizing energy losses as electricity travels through power lines.

In practical terms, UHV technology makes it possible to transmit massive amounts of electricity over distances exceeding 2,000 kilometers (1,200 miles) with minimal energy loss. This efficiency is particularly critical for countries like China, where renewable energy resources such as wind and solar are concentrated in remote regions, far from population and economic hubs.

China's UHV Ambitions: A Timeline of Innovation

China began exploring UHV technology in the early 2000s, driven by frequent power shortages and the need to connect its resource-rich western regions to the bustling eastern cities. The Xiangjiaba-Shanghai line, which became operational in 2010, was a landmark project. Spanning 1,900km, this DC link transmits hydropower from southwestern China's Jinsha River to Shanghai, meeting up to 40% of the city’s electricity demand.

Since then, China has rapidly expanded its UHV network. As of April 2024, the country operates 38 UHV lines, covering a total length of 48,000 kilometers. This infrastructure has become the backbone of China’s renewable energy strategy, supporting the integration of vast wind and solar farms with the national grid.

The Role of UHV in Renewable Energy Integration

UHV technology plays a critical role in overcoming the geographical and temporal challenges of renewable energy. Solar and wind energy generation often occurs in remote locations and varies with weather and time. UHV lines address these challenges by efficiently transmitting power to where it’s needed and balancing supply and demand across regions.

For example, when the sun sets in eastern China, solar farms in the west can continue generating power. Similarly, high winds in one part of the country can offset calm weather in another. This interconnectedness maximizes the utility of renewable resources and ensures stability in the power supply.

Challenges Facing UHV Deployment

Despite its transformative potential, UHV technology comes with significant challenges:

1. High Costs: Building UHV lines is capital-intensive. China has reportedly invested $222 billion in UHV projects to date. Each line requires careful planning, advanced technology, and extensive infrastructure.
2. Reliance on Coal Power: UHV lines often transmit coal-based electricity to ensure stability when renewable sources are insufficient. In 2022, 56.2% of the electricity transmitted by UHV lines in China came from renewable sources, with hydropower making up the bulk. However, wind and solar contributed only 27.25%, reflecting the need for further renewable energy development.
3. Limited Local Benefits: In some cases, UHV lines bypass local grids entirely. For instance, Sichuan Province, a major hydro hub, experienced power shortages even as its electricity was exported to other regions via UHV lines.

Global Impact and Adoption

China’s success with UHV has inspired other countries to adopt the technology. Brazil uses Chinese-built UHV lines to transmit hydropower from the Amazon Basin to urban centers like S?o Paulo. India has integrated UHV into its Green Energy Corridor project, enabling renewable energy transmission across its states.

Beyond national borders, China has proposed a Global Energy Interconnection (GEI)—a vision to link national grids worldwide through UHV technology. This ambitious plan aims to optimize clean energy use across continents, supporting the global energy transition.

The Future of UHV and Energy Transition

UHV is not a silver bullet but a critical component in a broader mix of solutions for sustainable energy systems. While UHV supports large-scale renewable energy integration, localized systems like microgrids also play a vital role. These smaller, community-based solutions provide resilience and energy security, especially in remote or developing areas.

Moreover, advancements in offshore wind and nuclear power could reduce the need for long-distance transmission in coastal regions. For instance, China’s coastal provinces are planning large-scale offshore wind farms, which could shift the focus from UHV to localized generation.

Conclusion: Lessons from China's UHV Experience

China’s investment in UHV technology offers valuable insights for the global energy community. It demonstrates how a large-scale approach can tackle the challenges of integrating renewable energy while highlighting the importance of a balanced strategy.

For countries aiming to accelerate their energy transition, UHV serves as a powerful tool to bridge the gap between renewable energy generation and consumption. However, its deployment must be complemented by investments in local energy solutions, storage technologies, and robust regulatory frameworks.

As the world races toward a carbon-neutral future, the "bullet train for power" may not be the final destination, but it is undoubtedly a key milestone on the journey.