The world’s largest and highest-altitude pumped storage power station under construction has reached two major milestones in western China’s Sichuan Province.
On 22 February, excavation of the underground powerhouse at the Lianghekou pumped storage power station was completed, and the first batch of concrete was poured for the dam of the Yagen I hydropower station, which will serve as the project’s lower reservoir.
The site is located at an altitude of approximately 3000m on the western Sichuan plateau along the Yalong River.
The Lianghekou pumped storage project uses the existing Lianghekou Reservoir as its upper reservoir and the Yagen I reservoir as its lower reservoir. It will install four 300MW reversible pump-turbine units. Combined with the 3000MW of conventional hydropower capacity at Lianghekou, the total installed capacity will reach 4200MW.
The underground powerhouse, situated about 500m below ground, measures nearly 200m in length and 60m in height, with a maximum excavation depth of 650m. Completion of excavation marks the end of the main civil works phase and allows the project to transition to electromechanical installation.
Construction teams on the project faced high-altitude conditions, low oxygen levels, high in-situ stress and fractured surrounding rock. According to project developers, a self-developed intelligent construction management platform was deployed, integrating BIM modelling, 3D laser scanning, intelligent drilling and blasting systems, and automated ventilation controls.
A layered excavation approach combining pre-splitting and smooth blasting techniques was adopted. Real-time deformation monitoring systems were installed to track surrounding rock stability and coordinate excavation and support works simultaneously.
During the Spring Festival period, more than 500 workers remained on site, operating on a 24-hour shift system to take advantage of dry-season conditions. The project deployed a domestically developed unmanned intelligent rock drilling rig capable of automated positioning and multi-arm collaborative operation. Developers report that the technology improved excavation efficiency by more than 30% and enabled completion three months ahead of schedule.
Once operational, the pumped storage station is expected to generate approximately 1.4TWh of electricity annually. It will also provide peak shaving and balancing services for around 7GW of surrounding wind and solar capacity in western Sichuan.
First concrete poured at Yagen I dam
On the same day, construction teams completed the first concrete pour for the dam of the Yagen I Hydropower Station. The 300MW facility is the second cascade station in the “One Reservoir, Seven Levels” development plan for the middle reaches of the Yalong River.
The project features what developers describe as China’s widest single-sluice dam section, with an individual block length of 47m. The design integrates the spillway bottom slab into a highly rigid structure intended to improve seismic performance.
High-altitude winter temperatures, large temperature differentials and complex aggregate characteristics have posed crack-control challenges during construction. To address these risks, the construction team implemented a full-process temperature management system, including aggregate heating, controlled mixing temperatures, insulated transport and monitored curing.
Steam curing and enclosed temperature- and humidity-controlled measures were adopted to reduce thermal cracking risks in the ultra-wide dam section. More than 600 workers remained on site during the holiday period to initiate the first pour on schedule.
Upon completion, Yagen I is expected to generate approximately 1.15TWh annually, saving an estimated 350,000 tonnes of standard coal and reducing carbon dioxide emissions by 940,000 tonnes per year. In addition to power generation, it will function as the lower reservoir for the Lianghekou pumped storage facility, enabling bi-directional energy regulation through pumping during off-peak periods and generation during peak demand.
Lianghekou pumped storage brings integrated clean energy
The Lianghekou project forms part of the Yalong River Basin integrated hydropower, wind and solar base – described as China’s first national-level integrated water-wind-solar power base.
The Lianghekou “Water, Wind, Solar, Storage, Hydrogen and Computing” Clean Energy Demonstration Zone has a planned installed capacity exceeding 50GW, accounting for about 60% of the total planned capacity of the basin-wide base.
The broader Yalong River integrated base has a planned total capacity of 78GW. To date, approximately 23GW has been commissioned and around 12 GW is under construction. Three major regulating reservoirs — Lianghekou, Jinping and Ertan — provide a combined regulating capacity of 14.8 billion cubic metres.
According to the Yalong River Company of the State Development & Investment Corporation (SDIC), the basin is targeting more than 40 GW of operational capacity by 2030 and full planned capacity of 78 GW by 2035. At that stage, annual generation is projected to reach around 200 TWh, supplying electricity equivalent to the annual consumption of approximately 100 million households.
Developers state that the Lianghekou pumped storage project is scheduled to support completion of the clean energy demonstration zone by 2028, contributing to China’s carbon peak and carbon neutrality objectives and expanding flexible capacity for large-scale renewable integration in western regions.
Source: State Development & Investment Corporation
