The world's first 660-kV direct current power transmission system began to supply energy from northwest China's Ningxia Hui Autonomous Region to the eastern Shandong Province Monday.

The 10.4-billion-yuan (US$1.58 billion) project is part of China's west-east power transmission program.

The cable system has a current-carrying capacity of 4 million kW of electricity traveling over a distance of 1,333 km through five provinces and regions.

To generate the same amount of electricity, about 13 million tons of coals would be needed along with 650,000 20-ton trucks need to deliver the coal.

Therefore, the cable system not only eases Shandong's energy needs, but also helps relieve traffic pressures on the roads.

Cui Jifeng, general manager of Ningxia Power Co., a subsidiary of the China Power Grid Co., said the system was built to supply hydropower generated on the upper reaches of the Yellow River, as well as thermal power produced in Ningxia to coastal Shandong.

The system was independently designed, produced, built and tested by Chinese companies, he noted.

China's coal resources are mainly based in the west and north, which are economically underdeveloped compared with the east. The west-east power transmission program was begun in 2000.

The State Grid Corp. plans to build six cable systems, including three west-east facilities and three north-south systems, between 2011 and 2015.

For coal-rich provinces, the cables will make their coal mines more profitable, said Pan Jiazheng, academician of the Chinese Academy of Sciences.

The revenues from mining and delivering 13 million tons of coal by trucks are about 2.59 billion yuan, while those of transmitting electricity generated by equal amount of coals can be 6.5 billion yuan, according to Pan.