Hundreds of miles from China’s populated coast, a sharp bend in a remote Himalayan river will become the centerpiece of one of the nation’s most ambitious—and contested—infrastructure undertakings to date.
There, a $168 billion hydropower system is projected to generate more electricity than any other in the world—a massive advantage for China as it surges toward a future where electric vehicles populate highways and energy-hungry AI models vie to outperform international rivals.
Chinese leader Xi Jinping called for the undertaking to “advance resolutely, systematically, and efficiently” during a rare visit earlier this year to Tibet—a region where Beijing continues to tighten its grip under the guise of economic advancement and stability.
The scheme could bolster global efforts to slow climate change, helping China—now the world’s largest source of carbon emissions—to pivot away from coal power. But its construction may also disrupt a rare, unspoiled ecosystem and the ancestral homes of indigenous peoples.
Tens of millions of people also rely on the river downstream in India and Bangladesh, where experts suggest the potential ecological impact, including on fisheries and agriculture, remains insufficiently examined.
Headlines in India have already branded the project a potential “water bomb”—and its proximity to the disputed border between China and India puts it at risk of becoming a flashpoint in the longstanding territorial disagreement between the two nuclear-armed nations.
Despite these stakes, the undertaking remains cloaked in secrecy, deepening questions about a plan that showcases China’s immense technical capabilities and clean energy drive, as well as its lack of openness, even concerning a project with potentially far-reaching ramifications.
Clues about the scheme’s design—from official or academic papers and open-source information compiled by CNN—suggest a complex arrangement that may involve dams and reservoirs along the Yarlung Tsangpo River, along with a series of underground power stations linked by tunnels, utilizing the energy as a diverted section of the river steeply drops in elevation.
China disagrees. In a statement to CNN, the Ministry of Foreign Affairs conveyed that the project “has gone through decades of in-depth study” and has “implemented rigorous safety and environmental protection measures to guarantee it will not negatively affect downstream areas.”
“Since the initial preparation and official launch of the project, the Chinese side has always been transparent regarding important information and maintained open channels of communication with downstream nations,” the ministry stated, adding that as the project progresses, Beijing will “share necessary information with the international community” and “strengthen communication and cooperation with downstream countries.”
The project, it said, “aims to accelerate the development of clean energy, improve local livelihoods, and actively address climate change.”
But Beijing may have other priorities in mind, too. The ambitious infrastructure move comes as Xi pushes to shore up national security not just by ensuring China’s energy supply – but also tightening control along disputed borders and regions home to ethnic minorities.
“If you connect the dots of Chinese infrastructure development in the Himalayas, especially in areas where China borders India along Tibet, they are strategically positioned,” asserted Rishi Gupta, associate director for policy at the Asia Society Policy Institute in New Delhi.
“The project aligns with China’s broader goal of utilizing its natural resources to reinforce control over critical territories like Tibet and its frontiers.”
A Power Play in the Himalayas
The Yarlung Tsangpo, known as the world’s highest major river, winds from a glacier in the Himalayas across a plateau that sheltered Tibetan Buddhism, to the nation’s southernmost edge.
One section of the river, situated along the de facto boundary of Tibet with an Indian state whose lands China claims, has long drawn attention for its power-generating potential.
There, the waterway makes a sharp horseshoe turn, looping around massive mountains in the so-called Great Bend—a trajectory where the river loses roughly 2,000 meters in elevation over about 50 kilometers.
This descent is estimated to be capable of generating approximately 300 billion kilowatt-hours of electricity annually—about three times the capacity of China’s Three Gorges Dam, currently the largest in the world.
Such a scheme along the lower reaches of the river has been discussed for decades but never realized—long considered an exceedingly difficult venture in a remote and perilous area, challenging even for a nation that leads the world in constructing megadams.
Now, satellite imagery, publicly available corporate papers, and social media posts from the area reviewed by CNN show ongoing work to construct and widen roads, build bridges, erect explosives depots, expand cellular coverage, and relocate villagers—all apparent efforts toward construction that officially commenced in July.
A cycling vlogger records his journey to a checkpoint for entering a highway CNN believes is located near to where the hydropower project’s water-diversion tunnel system is located. The road has been closed to public access. Douyin
Official documents often refer to the project using the Roman initials “YX” to denote an abbreviation for the lower reaches of the Yarlung Tsangpo, but they provide limited information about its design. State media has said the project primarily employs a method of “straightening and diverting the river” through tunnels and includes five cascade hydropower stations.
CNN’s examination of open-source information, including academic research papers, official tenders, patents for power station designs filed by a subsidiary of PowerChina, a local town planning document, as well as satellite imagery and social media posts from the area has shed more light on how this expansive project may be taking shape.
A simulation based off this information and produced in conjunction with experts at the Stimson Center’s Energy, Water, and Sustainability Program, who provided technical and geographic analysis, suggest the design could be a sprawling system of hydropower stations, tunnels and reservoirs, which together could span some 150 kilometers as the crow flies from the first to the final power station.
This arrangement would commence with a reservoir created by a dam in Mainling county, where Chinese Premier Li Qiang attended the project’s groundbreaking ceremony in July. The reservoir there—which a simulation suggests could stretch for scores of miles—would let operators regulate water flow throughout the hydropower complex.
A second, lower dam situated downstream and beyond a protected national wetland would likely be used to divert some of the river away from the Great Bend into a tunnel network bored through the mountains and beneath a nearby valley, according to modeling of the potential scheme.
Here, diverted water would probably pass through a series of cascade power stations, each situated hundreds of meters lower than the last—generating immense power along the way before rejoining the main river.
Another crucial question for such a project is whether the system would incorporate a final dam and power station, allowing operators to manage the overall flow of the primary river before it passes downstream.
Experts note that a final dam, which could include a power station and be situated nearer the de facto border with India, would be an addition to the core project due to cost, complexity, and potential hazards.
An article by Chinese researchers published in the journal Nature Communications Earth & Environment earlier this year appeared to confirm that two reservoirs upstream of the diversion tunnels would regulate the amount of water entering those tunnels, whereas a third, downstream, would manage the water flow back into the main river. However, experts stress that until China releases more specifics, independent efforts to assess the scheme can only rely on educated guesses.
“Given what we know, it’s practically impossible to grasp (or) estimate the potential consequences of the project,” remarked Rafael Yang Pablo Schmitt, a hydropower specialist at the University of California, Santa Barbara, who discussed the simulation with CNN and the Stimson Center.
Clearly, to construct the hydropower complex, Chinese engineers and hydrologists will have to operate in exceedingly challenging terrain. The river runs through one of the world’s most seismically active regions, where the mountains themselves continue to rise by millimeters each year—risking disruption to a finely calibrated engineering system.
“The challenge will be building a system that can mitigate or avert safety risks,” said Euler. “The system is extremely elaborate. A lot of concrete is being poured for multiple dams and tunnels cutting through seismically dynamic mountains. China prioritizes dam safety… but can you mitigate risk in the Himalayas?”
Landslides, debris flows, and glacial lake outburst floods—all features of the region made more unpredictable by climate change—could potentially damage infrastructure and endanger downstream populations should the project falter.
Experts point out that Chinese engineers are among the world’s finest and have devised measures to reduce the impact of earthquakes and other perils—but they will be tested as never before in such an environment.
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