A 289-metre arch dam is only half the engineering story at Baihetan. The other half is invisible from the outside: sixteen 1-gigawatt turbine-generator units, the largest hydropower turbines ever built, installed entirely inside the mountain in an all-underground powerhouse.

President Xi Jinping, in a letter marking the plant's first turbine startup, called it the largest and most technically difficult hydropower project under construction in the world at the time — a description that holds equally for the concrete arch above ground and the machine hall carved into rock below it.

289 m
Dam height
16×1 GW
Turbine-generator units
2,100 t
Generator rotor weight
2017–22
Construction span
Phase 1 — The double-curvature arch dam
Curved in two directions to carry the load
The 289 m tall concrete double-curvature arch dam, with a crest elevation of 827 m, a crest width of 13 m, and a maximum base width of 72 m, transfers the reservoir's load into the surrounding rock through arch action in both the horizontal and vertical planes — a design that allows a thinner, more material-efficient structure than a straight gravity dam of the same height.
Phase 2 — Excavating the underground powerhouse
A machine hall built into the mountain
Rather than a conventional above-ground powerhouse, Baihetan's 16 generating units are housed in an all-underground powerhouse layout — a cavern excavated deep into the rock alongside the dam, engineered to hold turbines larger than any hydropower project had previously installed.
Phase 3 — A tandem-crane lift, 300 metres, 1.5 hours
Two 1,300-tonne overhead cranes, one rotor
No single crane in the powerhouse could lift a 2,100-tonne rotor alone. Two 1,300-tonne overhead bridge cranes, spanning the cavern's crane beam, worked in tandem to hoist Unit 1's rotor on 18 August 2020 — traveling roughly 300 m horizontally under crane traction before being lowered into the unit pit and precisely docked with the generator shaft. Continuous adjustment of the rotor's center position completed the installation in about 1.5 hours, a level of control the industry describes as millimetre-accuracy on a 2,100-tonne load.
Phase 4 — Repeating the sequence, sixteen times
A cavern engineered around the crane, not just the turbine
The same tandem-crane sequence — hoist, horizontal travel, lower, dock, align — repeated for each of the 16 units across both underground powerhouses, each 450-plus metres long with an excavation height of 88.7 m above and below the crane beam. Unit 2's rotor followed on 9 September 2020, with the remaining units installed in stages through 2021.
Phase 5 — Sequential commissioning
Sixteen units, brought online in stages
The first two turbines began generating electricity in June 2021, with the underground facilities completed that October. Units were commissioned in stages through 2021 and 2022, with all 16 units becoming fully operational on 20 December 2022.

No single crane could lift it. Two 1,300-tonne overhead cranes, moving as one system, carried the rotor 300 metres and docked it to millimetre accuracy in 90 minutes.

Baihetan was developed by China Three Gorges Corporation (CTG) through a joint venture with Sichuan Energy Investment Group and Yunnan Energy Investment Group, with turbine-generator units supplied by Dongfang Electric Machinery and Harbin Electric Machinery. It stands as the world's second-largest hydropower station by capacity, after the Three Gorges Dam, and as a reference case for combining extreme-scale civil construction with turbine installation at a size the hydropower industry had never previously attempted.

For further reading on erection engineering in industrial construction, see Erection Engineering in Industrial Construction

Related case studies: China Offshore Converter Station · Vogtle Nuclear Plant

Core concepts: What is erection engineering? · What is heavy lift engineering?

Two-panel schematic of Baihetan: a section of the 289 m double-curvature arch dam with a 13 m crest width, crest elevation 827 m, and 72 m maximum base width; and a cross-section of the underground powerhouse cavern where two 1,300 t overhead bridge cranes on the crane beam lift a 2,100 t generator rotor in tandem, travel about 300 m horizontally and lower it into the unit pit in about 1.5 hours, repeated for 16 units.
Baihetan — a 2,100 t rotor lifted by two cranes inside a mountain.
Diagram: EE&HL Network, 2026. Conceptual schematic — not to scale.
Tap or click the diagram to open it full size.

Sources: China Three Gorges Corporation — owner's account of the rotor hoist: the 2,100-tonne rotor of the world's first 1 GW hydropower generator lifted by two 1,300-tonne overhead bridge cranes working in tandem, travelling roughly 300 m before being docked with the generator shaft. Figures are reported as published. All 16 units became fully operational on 20 December 2022.

Frequently Asked Questions

The Baihetan dam is a 289 m tall concrete double-curvature arch dam, with a crest elevation of 827 m, a crest width of 13 m, and a maximum base width of 72 m. Construction began in 2017.

Baihetan's 16 Francis turbine-generator units each have a capacity of 1 gigawatt — the world's largest hydropower turbines — and are housed entirely underground in an all-underground powerhouse layout. Each generator rotor weighs approximately 2,100 tonnes, stands 4.1 m tall, and measures 16.2 m in diameter.

No single crane in the powerhouse could lift a 2,100-tonne rotor alone. Two 1,300-tonne overhead bridge cranes, spanning the cavern's crane beam, worked in tandem to hoist Unit 1's rotor on 18 August 2020 — traveling roughly 300 m horizontally under crane traction before being lowered into the unit pit and precisely docked with the generator shaft, with the full installation completed in about 1.5 hours.

Baihetan was developed by China Three Gorges Corporation (CTG) through a joint venture with Sichuan Energy Investment Group and Yunnan Energy Investment Group. Turbine-generator units were supplied by Dongfang Electric Machinery and Harbin Electric Machinery.