State Grid tests tethered balloon for high-altitude power construction in Xizang

China's State Grid has finished testing the country's first tethered balloon capable of carrying a 2-metric-ton load in the Xizang autonomous region section of the ultra-high voltage direct current (UHVDC) transmission project, Xizang Daily reported.

The 25-meter-wide balloon transported 2 tons of transmission tower materials to a steep ridge at an altitude of more than 4,000 meters without the need to build roads or install cableways.

The trial section was entirely located in uninhabited mountains, with most tower foundations on steep ridges inaccessible by road. Traditional road construction is costly and can damage the environment, while cableways face terrain constraints.

Connected by cables to a ground control system, the balloon can adjust its altitude and horizontal position to transport materials between designated points.

Tu Dejun, director of the Transmission and Transformation Engineering Technology Research Institute at State Grid, said the team developed the system to overcome instability and route deviation caused by strong winds.

Feng Tao, a project manager with State Grid Henan, said the balloon is more flexible and less dependent on terrain than conventional cableways. It can carry heavier loads than drones and remain airborne longer.

The technology is part of China's growing use of heavy-lift drones, transport airships, and tethered balloons for power grid construction in high-altitude and remote mountainous areas, it said.