When most people picture a battery big enough to matter to a power grid, they picture a box. A Powerwall bolted to a garage wall, or one of those steel Tesla Megapack containers lined up in a field in Texas or, lately, the Australian outback. But the largest energy-storage machines on the planet do not look anything like that. They look like two lakes stacked on top of each other with a mountain in between, and the highest one anybody has ever tried to build is going up right now at roughly 14,100 feet, on the Tibetan Plateau in southwest China.<\/p>\n
It is called the Daofu pumped-storage power station, and the figure circulating online is real: more than 2.994 billion kilowatt-hours of electricity a year, with 2.1 gigawatts of installed capacity. According to the official announcement carried by Xinhua<\/a> when crews broke ground, it is set to become the world’s highest-altitude mega pumped-storage station once it is finished. The catch, and it is a big one the breathless headlines tend to skip, is that it is not finished. It is not close.<\/p>\n Pumped storage is an old idea doing a very modern job. You build two reservoirs at different heights and connect them with tunnels and turbines. When the grid has more electricity than it needs, usually in the middle of a sunny afternoon, you spend that surplus power pumping water from the lower lake up to the higher one. When demand spikes and supply gets tight, you let the water fall back down through the turbines, and it generates electricity on the way down. The water is the battery. Gravity does the discharging.<\/p>\n Daofu’s version is built around a 760-meter height difference between its reservoirs, about 2,500 feet, which makes it the second-tallest pumped-storage station in China by operating head. Inside an underground powerhouse sit six reversible generating units, each rated at 350 megawatts, that run as pumps in one direction and generators in the other. Add an upper reservoir, a lower reservoir, the water conveyance system and a surface switchyard wired into Sichuan’s grid at 500 kilovolts, and you get a machine designed to store about 12.6 gigawatt-hours of energy a day. The state developer puts that at enough to cover the daily electricity needs of roughly two million households in Sichuan.<\/p>\n None of this is free, or as efficient as the word “battery” makes it sound. A pumped-storage plant burns more electricity lifting the water than it ever gets back when the water comes down, with round-trip efficiency landing somewhere around 70 to 80 percent for a good one. What it buys you is timing. It shifts cheap, abundant midday power to the evening, when people get home and switch everything on, and that is the whole point.<\/p>\n Daofu broke ground in January 2024, after years of feasibility studies that ran through the Sichuan Provincial Development and Reform Commission. It was the first large-scale conventional pumped-storage project the province approved, with a total investment of around 15.1 billion yuan (about $2.11 billion). All of that is confirmed and on the record.<\/p>\n What is not on the record, anywhere, is the plant generating power. Through early 2026, project updates from PowerChina, the state contractor building it, still placed Daofu in early-stage construction, with access roads doing a lot of the work before the main civil engineering can really get going. No official source describes it as operating. So when an article tells you a Chinese water battery is “producing” three billion kilowatt-hours a year and powering two million homes today, read it as a design target sitting on a construction site, not a meter reading.<\/p>\n The reason it is taking a while is not incompetence. It is altitude. Yu Chuntao, the project’s director at PowerChina Chengdu, told the Global Times<\/a> there is almost no playbook for building pumped storage this high up, and called the design and construction “highly exploratory and challenging.” Cold, thin air, a 4,300-meter site, a high water head, high voltage, very large machines. This is the kind of slow, enormous infrastructure that, like Britain’s recent 500-ton nuclear reactor lift with the largest crane on Earth<\/a>, ends up measured in years and millimeters rather than press releases.<\/p>\n It is also worth being precise about which record Daofu is chasing, because two get mixed up constantly. Daofu is set to be the world’s highest, not the world’s largest. The largest pumped-storage plant by installed capacity is the Fengning station in Hebei province, near Beijing, which only reached full operation at the end of 2024<\/a> at 3.6 gigawatts. The previous altitude record belonged to the Yamzho Yumco station in Tibet, sitting at about 3,600 meters. Daofu beats the altitude mark by some 700 meters. It does not touch Fengning’s size.<\/p>\n Daofu is not a vanity record. It is parked next to a lot of solar. The state developer, Yalong River Hydropower Development, a subsidiary of the state-owned SDIC, says the area around the station holds more than 20 gigawatts of photovoltaic resources, and that the pumped-storage plant could help smooth roughly 6 gigawatts of that variable solar into something the grid can lean on. The whole project is one piece of a much larger water-and-solar base SDIC is assembling along the Yalong River.<\/p>\n That is the logic behind the national push, too. Solar panels and wind turbines only cut fossil-fuel use when their power can be delivered at the hour it is needed, and on a bright, breezy day a region can make far more electricity than anyone wants right then. Storage is the bridge. China already had around 50 gigawatts of operational pumped storage as of May 2023, roughly 30 percent of the global total, according to the U.S. Energy Information Administration<\/a>, and it has been building hard ever since. The International Hydropower Association’s 2025 outlook<\/a> put China’s 2024 additions at 14.4 gigawatts of hydropower, more than half of it pumped storage, with the country on track to blow past a 120-gigawatt target for the technology.<\/p>\n The strange part is that pumped storage is technically losing the storage race inside China. New lithium battery capacity has grown so fast that, by the first half of 2025, batteries made up close to 60 percent of the country’s storage while pumped hydro had slipped to around 37 percent, according to industry tracking reported by pv magazine<\/a>. Tesla Megapacks and their Chinese rivals go up in months. Daofu takes the better part of a decade.<\/p>\n So why bother stacking lakes on a mountain at all? Duration, scale and lifespan. A wall of Megapacks like the one that recently switched on in the Australian outback<\/a> typically discharges for a few hours at a time. A plant like Daofu is built to move gigawatt-hours around for far longer, and to keep doing it for fifty or sixty years with cheap water as the working fluid. China is hedging across both ends at once, the same way it is funding longer-shot chemistry like a lab battery that stores electricity and hydrogen in the same device<\/a>. Pumped hydro is the heavy, boring, proven end of that bet.<\/p>\n The honest version of the Daofu story is less cinematic than the headline. There is no giant water battery humming away at 14,100 feet right now, banking three billion kilowatt-hours and feeding two million homes. There is a hard, high, half-built construction site that, if everything goes to plan, will eventually do exactly that, and will hold the altitude record when it does. The numbers are approved and the money is committed. The water just has not started falling yet. For a country trying to stretch a record-breaking amount of solar across the hours after the sun has gone, that mountain is worth the wait, access roads and all.<\/p>\n","protected":false},"excerpt":{"rendered":" When most people picture a battery big enough to matter to a power grid, they picture a box. A Powerwall … <\/p>\nTwo lakes, a mountain, and a 760-meter drop<\/h2>\n
The numbers are real. The plant is not, yet<\/h2>\n
Why China keeps pumping water up a mountain<\/h2>\n
Lithium batteries are winning, and this still gets built<\/h2>\n