PU'ER -- The largest hydropower station on Lancang River in southwest China's Yunnan Province -- known as the Mekong River in southeast Asia -- went into operation Thursday with its first power generating unit up and running.

The Nuozhadu hydroelectric station, located in the city of Pu'er, is China's 4th largest of its kind. It will be installed with nine same-size generating units with a total capacity of 5.85 gigawatts.

All the units will be put into operation by 2014, thus enabling the station to generate 23.9 billion kwh of electricity on average each year.

By churning out clean energy, the station will help save 9.6 million tonnes of standard coal and reduce carbon dioxide emissions by 18.8 million tonnes each year.

The dam of the Nuozhadu station is 261.5 meters high, the highest in Asia and the world's third highest.

As one of the seven planned hydropower projects on Lancang River inside China, the station will increase the electricity supply and optimize the energy mix and also help flood control and water use downstream, said Yunnan governor Li Jiheng.

The Lancang River, or Mekong River, rises on the Qinghai-Tibet Plateau and flows through China, Myanmar, Laos, Thailand, Cambodia and Vietnam before spilling into the South China Sea.

The river's China section has an estimated 32 gigawatts of exploitable water power resources as it flows through high mountains and valleys, with a huge drop in height at some points.

During the hydropower development, China has paid great attention to the protection of the river valley ecosystem and environment as well as water allocation along the river valley.

In recent years, many contractors and research institutes have conducted investigations with overseas counterparts on the impacts of hydropower development on downstream regions.

The research results showed that the water flow in the river's China section accounted for only 13.5 percent of the river's total, making the country's hydropower development have little impact downstream.

"First, the water flow inside China has a small share of the whole river valley; Secondly, hydropower generation doesn't consume water," said Ma Hongqi, an academician of the Chinese Academy of Engineering. "So the hydropower development on the upper reaches has very limited impact on the water flow downstream."

Meanwhile, the dam stores water during the flood season and releases it during the dry season, which could help ease both flooding and drought in the countries downstream, Ma said.

Huaneng Lancang River Hydropower Co Ltd, which runs the hydropower station, has also made efforts to protect the ecosystem and the fish in the river.

Wang Yongxiang, chairman of Huaneng Lancang River Hydropower, said the company has set up botanical gardens of rare plants and animal saving stations and also has taken measures to ensure zero emissions at the hydropower project.