Chinese authorities have begun constructing what will be the world’s largest hydropower dam.

Chinese Premier Li Qiang presided over a ceremony marking the start of construction on the Yarlung Tsangpo river on Saturday, according to local media.

Photo: NASA

The river flows through the Tibetan plateau. The project has attracted criticism for its potential impact on millions of Indians and Bangladeshis living downriver, as well as the surrounding environment.

Beijing says the scheme, costing an estimated 1.2tn yuan ($167bn; £125bn), will prioritise ecological protection and boost local prosperity.

When completed, the project – also known as the Motuo Hydropower Station – will overtake the Three Gorges dam as the world’s largest, and could generate three times more energy.

Made up of five cascade hydropower stations with the capacity to produce 300 billion kilowatt-hours of electricity annually, equal to the amount of electricity consumed by Britain last year, the dam will be located in the lower reaches of the Yarlung Zangbo. A section of the river tumbles 2,000 metres (6,561 feet) in a span of 50km (31 miles), offering huge hydropower potential.

Beijing has said the dam will help meet power demand in Tibet and the rest of China without having a major effect on downstream water supplies or the environment. Operations are expected sometime in the 2030s.

The Chinese premier described the dam as a “project of the century” and said special emphasis “must be placed on ecological conservation to prevent environmental damage,” Xinhua said.

The project, overseen by the newly formed state-owned China Yajiang Group, marks a major boost in public investment to help bolster economic growth as current drivers show signs of faltering.

“Assuming 10 years of construction, the investment/GDP boost could reach 120 billion yuan ($16.7 billion) for a single year,” said Citi in a note. “The actual economic benefits could go beyond that.”