A pumped storage plant is a battery made of two ponds and a machine between them, and the smaller pond decides how big the battery is. Fill that pond and everything stops, however much room is left upstream. EDF has a scheme in the French Jura where the lower pond runs out in a few hours while the lake above it sits nowhere near full.<\/p>\n
The fix EDF ordered on July 20 is a single pump turbine rated at 17 megawatts.<\/p>\n
It goes into Saut-Mortier, a 44-megawatt station on the Ain river with two Kaplan turbines in it. ANDRITZ<\/a> builds the pump turbine. Ingeteam, the Spanish power electronics firm, builds the motor generator and the converter that lets the unit run at variable speed. ANDRITZ puts the order in the lower double-digit million-euro range and booked it in its second-quarter intake for 2026. Work runs from 2026 to 2031.<\/p>\n Storage across the three reservoirs goes from 50 gigawatt-hours to 250.<\/p>\n Vouglans is the third-largest hydroelectric reservoir in France, held back by a dam commissioned in 1968 in the Jura. EDF runs the plant at its foot with three Francis turbines and one reversible pump turbine, 285 megawatts in total. Saut-Mortier sits immediately downstream, in service since 1966, 44 megawatts across two Kaplans. Below that again is Coiselet, at 42.<\/p>\n Water already moves back uphill here. Vouglans has been pumping from Saut-Mortier for decades.<\/p>\n EDF says<\/a> the Saut-Mortier reservoir empties within a few hours under pumping, which caps how much water ever reaches Vouglans. The new machine adds a third rung to the ladder. Water can be lifted out of Coiselet into Saut-Mortier, then from Saut-Mortier into Vouglans, and EDF says that gives the cascade four times the recycled water volume it works with today. None of the three dams gets any bigger. The water just gets one more place to come from.<\/p>\n EDF calls the result the first three-basin pumped storage scheme in France, joining the six it already operates.<\/p>\n EDF put the job out on the EU procurement platform TED on October 23, 2024, with bids due November 19. Hydropower and Dams<\/a> reported the notice at the time: an 18-megawatt unit built around a Francis-type pump turbine, a generator, the voltage source inverter that varies its speed, medium-voltage connections and mechanical auxiliaries, estimated at \u20ac32 million excluding VAT, a little under $40 million. The notice put six years of work at the Saut-Mortier dam, from June 30, 2026 to June 30, 2032.<\/p>\n ANDRITZ’s announcement 21 months later names 17 megawatts and does not say Francis. Its scope covers design, manufacturing, assembly, commissioning and the turbine governor. Ingeteam takes the motor generator and the full-power converter.<\/p>\n The Rh\u00f4ne M\u00e9diterran\u00e9e Corse water agency, which is co-funding the work, puts the whole project at \u20ac120 million, close to $140 million, with its own grants capped at \u20ac21 million.<\/p>\n A fixed-speed pump turbine pumps at one rate. It is on or it is off. A variable-speed machine changes how hard it pumps, which is the entire reason Ingeteam’s converter is in the contract: the unit can follow what the grid is doing minute to minute instead of taking one fixed bite of power and holding it.<\/p>\n That matters more at Saut-Mortier than 17 megawatts suggests. The head here is low. Saut-Mortier’s dam is a gravity structure about 66 feet tall, nothing like the 715-foot drop ANDRITZ turbines work against at Kidston in Queensland<\/a>. Low head means small machines and awkward operating ranges, and variable speed is how you hold efficiency across them.<\/p>\n ANDRITZ says the new unit raises the total output of Vouglans and Saut-Mortier by around 80 to 85 megawatts. EDF’s project page says the scheme becomes an 84-megawatt pumped storage station. One is an increase and one is a total.<\/p>\n EDF’s earlier project brochure put the new equipment at 16 megawatts of added installed capacity. STOR-HY<\/a>, the EU-funded research project that lists the cascade as a demonstrator site, credits it today with 362 megawatts of generation and 72 of storage. Add 17 to that 72 and you are within a few megawatts of EDF’s 84.<\/p>\n Saut-Mortier is rated at 44 megawatts. Adding 80 to 85 to that would take the station to nearly triple what it does now, which is not what any other document about the project describes.<\/p>\n On storage the two agree. ANDRITZ’s release says that “energy storage capacity will expand from 50 GWh to 250 GWh.”<\/p>\n The Department of Energy<\/a> puts the entire US pumped storage fleet at about 22 gigawatts of generating capacity and 550 gigawatt-hours of stored energy, spread across every region of the country, accounting for 88 percent of all utility-scale energy storage in America. Bath County in Virginia, at 3,003 megawatts, is the largest of them and has been running since December 1985.<\/p>\n Vouglans and its two downstream ponds will hold 250 gigawatt-hours between them, against 550 for that entire American fleet.<\/p>\n Vouglans is a river reservoir rather than a purpose-built upper pool, and a large share of that 250 is water the Ain delivers rather than water any pump lifted. Bath County works a closed cycle sized to a single day. Both get called storage. They are not the same machine.<\/p>\n That distinction is why the storage argument sounds different depending on where you are standing. Britain is fighting over four schemes on one loch<\/a>. A Houston company is drilling its own head two miles into the ground<\/a>. EDF is doing the cheapest version of all of them, which is adding one machine to a valley that was already plumbed.<\/p>\nSaut-Mortier runs dry in a few hours and Vouglans never gets to run flat out<\/h2>\n
EDF advertised 18 megawatts and \u20ac32 million, and the machine that won is 17<\/h2>\n
Variable speed is the expensive part, and it is what makes a small machine worth buying<\/h2>\n
EDF and ANDRITZ do not publish the same power figure<\/h2>\n
One valley in the Jura will hold close to half of what every American plant holds<\/h2>\n
Three reservoirs come down in 2028<\/h2>\n