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Super grid

technology Maturity 11-13 Next article →

A super grid is a massive wide-area transmission network. It is designed to move huge volumes of electricity across very long distances. These networks are often trans-continental or multinational in scale. Because they connect so many regions, they are sometimes called mega grids.

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The primary goal of a super grid is to enable the trade of energy between distant locations. This capability is essential for a global energy transition. By connecting different regions, super grids can smooth out local fluctuations in wind and solar energy. This helps make renewable energy more reliable and helps mitigate global warming.

To move power efficiently, super grids typically use high-voltage direct current (HVDC) technology. HVDC refers to electricity that flows in a single direction at very high pressure. This method is much more efficient for long distances than standard alternating current. The latest generation of HVDC power lines is incredibly efficient. They lose only about 1.6% of their energy for every 1,000 km traveled.

AWEA proposed 765KV AC super grid for US wind
AWEA proposed 765KV AC super grid for US wind

This efficiency allows energy to travel from remote wind farms or solar deserts to distant cities. Some experts also discuss using high-voltage alternating current (HVAC) systems. For example, American Electric Power has championed a 765 kV AC super grid called I-765. This specific plan aims to carry 400 GW of wind power from the U.S. Midwest to other regions.

There are two main ways to think about how a super grid is structured. The first sense is as a superstructure or an overlay. In this model, the super grid acts like a superhighway system sitting on top of local city streets. It is a layer of HVDC lines that is distinctly separate from existing regional grids. The second sense describes a superior grid with advanced intelligence. This type of grid is highly coordinated from a macro level down to a micro level. It can manage everything from entire nations down to individual water heaters or refrigerators. This level of coordination allows the grid to act as a single, intelligent system.

Modern super grids are increasingly being compared to the Internet. Just as the Internet connects many small, private networks into one global web, a super grid integrates local grids into a single wide-area system. This integration allows for bidirectional energy flow. This means electricity does not just move from a power plant to a home. It can also move from a home back to the grid. For instance, a rural area might generate more solar power than it uses. It can then send that extra energy back into the system. Even a city with one million electric vehicles could help by using vehicle-to-grid technology to balance supply.

The history of long-distance transmission began well before modern super grid concepts. In the 1950s, a U.S. proposal to move hydroelectric power from the Pacific Northwest to California was scrapped. However, in 1961, President John F. Kennedy authorized a major project using Swedish HVDC technology. This was a collaboration between General Electric in the U.S. and ASEA in Sweden. The system was commissioned in 1970 and is now known as the Pacific DC Intertie. It currently has a capacity of 3,100 MW. Meanwhile, the term "Supergrid" has been used in Great Britain since the 1960s. In the British Grid Code, it refers to parts of the system connected at voltages above 200 kV.

Scaling these systems to a continental level presents significant technical challenges. Large grids face issues like network complexity, transmission congestion, and the need for rapid control systems. If not managed well, sudden disturbances can cascade across neighboring utilities. To prevent major outages, engineers use smart grid features like wide area sensor networks (WAMS). They also use phasor measurement units to detect imbalances instantly. These tools allow the network to respond automatically to fluctuating renewable sources. Without these advanced controls, the complex interactions between different power groups could become violent or unstable.

Estimates for the scale of these projects are massive. One study for a European super grid suggests that 750 GW of extra transmission capacity would be needed. This could be built using increments of 5 GW via HVDC lines. Building such systems requires immense amounts of land and money. For example, a 1,600-km HVDC line in Canada was priced at US$3 billion. In India, a 1,825-km proposal was priced at $790 million. These projects also face social challenges. People often oppose the construction of new power lines due to concerns about visual impact, the environment, or perceived health issues.

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