China aims 27 mirrors at frozen mountainside to speed up world's tallest dam

China aims to construct a towering dam on a frozen mountain, utilizing 27 mirrors to hasten the project. The three of four, 500 MW Francis turbines at the Shuangjiangkou station have already begun operation. Located in the upper reaches of the Dadu River, within Aba Tibetan and Qiang Autonomous Prefecture, this dam claims the title of the world's tallest at 315 meters.

The embankment reached approximately 260 meters of fill by early July, as reported by the National Energy Administration. The crest, scheduled for completion in 2027, would surpass the current record holder, the 305-meter Jinping-I arch dam, by 10 meters. With a total installed capacity of 2 GW and a reservoir capable of holding 2.9 billion cubic meters of water, the station is expected to reach full capacity by the end of 2026.

The first unit began operating in June, delivering 500 million kilowatt-hours, enough to meet peak summer demand in the Chengdu-Chongqing economic region. Beyond generating clean power, the reservoir helps store water when inflows are high, releasing it during peak demand or dry spells. This adaptability becomes increasingly valuable as wind and solar power expand, providing grid stability.

Engineers installed 27 heliostats to direct sunlight onto the clay core, raising temperatures by around 3 degrees Celsius and adding approximately three extra hours of work on suitable days. The project demonstrates China's ability to build the world's highest-grade rockfill dams and high-head flood discharge systems without foreign technology.

Environmental concerns include altered flows, water temperature changes, aquatic habitat damage, flooded vegetation, and the resettlement of residents. China added 6.03 GW of hydropower capacity in the first half of the year, bringing total installed capacity to 454 GW.