China on Friday begun construction on the Yunnan section of the landmark ultra-high-voltage (UHV) direct current transmission project that will carry clean energy from Xizang Autonomous Region in southwest China across thousands of kilometers to the Guangdong-Hong Kong-Macao Greater Bay Area in south China.

The project stretches approximately 2,681 kilometers and runs through four provincial-level regions, which include southwest China's Yunnan Province and Guangxi Zhuang Autonomous Region in south China.

After becoming fully operational in 2029, the line, with a rated capacity of 10 GW, will deliver more than 43 billion kWh of electricity annually from the clean energy base in southeastern Xizang to the Guangdong-Hong Kong-Macao Greater Bay Area.

With an investment of approximately 9.7 billion yuan (about 1.42 billion U.S. dollars), the project section in Yunnan is 1,094 kilometers long, making it the longest among the four provinces and regions.

The terrain is complex and the conditions are harsh at the construction site. Take the section at Gongshan Dulong and Nu Autonomous County as an example: the section of the line at an altitude of over 3,000 meters stretches for 25 kilometers, and the highest power transmission tower stands at an altitude exceeding 4,000 meters.

To ensure smooth progress of the construction, workers will use heavy-lift drones to transport materials and equipment. The Yunnan section is expected to be completed in 2028.