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PNNL Studies Battery Benefits at NW Hydro Dams by K.C. Mehaffey NW Fishletter, February 5, 2026

Energy could be replaced with interregional power purchases
stored in batteries alongside energy efficiency improvements.

After demonstrating that adding batteries can help hydroelectric facilities save money while improving conditions for fish, the Pacific Northwest National Laboratory will test their findings on hydropower facilities in central Washington state.

In a recent modeling study, PNNL used generation data from the 240-MW Bagnell Dam on the Osage River in Missouri and theoretically paired it with a 60-MW two-hour battery system to find that the project could generate an additional $6 million annually -- enough to recoup the battery investment in less than 10 years.

By preventing the intermittent stopping and starting of turbines, adding batteries could also extend the lifespan of hydropower equipment and prevent the choppy river conditions that make it harder for fish to pass through dams, PNNL found.

Now, PNNL will analyze the potential benefits of adding batteries at two Grant County Public Utility District dams on the Columbia River and one Energy Northwest dam on the Cowlitz River.

"Battery storage is one of the resources Grant PUD was already considering to increase its ability to store electricity until it's needed, either to supply our load or to sell on the market," Rich Flanigan, Grant PUD's vice president of energy supply markets, told Clearing Up in an email. "We decided to move forward with the study, because all PNNL asked us for was data about our dams' operations -- something we could provide without overly burdening our own busy staff," he said.

Data from Grant PUD's Wanapum and Priest Rapids dams, with a total capacity of nearly 2,172 MW, and Energy Northwest's 27.5-MW Packwood Lake Hydroelectric Project will help PNNL determine if smaller and larger projects could also benefit from using batteries.

"Hydropower has traditionally acted as the battery of the grid, with water stored in reservoirs ready to spin turbines when needed," Vishvas Chalishazar, a PNNL senior power systems research engineer, said in a news release. "But now our grid ‘battery' has the opportunity to have batteries of its own."

The study considered how adding batteries could reduce the repeated stops and starts that wear down a dam's mechanical parts, and which can lead to hundreds of thousands of dollars in operating costs as well as production losses.

"When electricity from hydropower is not needed, operators can continue to allow water to flow through the turbines, which will charge the attached battery. Then, when power is needed again, hydropower operators can dispatch electricity from the battery," PNNL noted.

The Bagnell Dam uses a process called synchronous condensing -- which keeps turbines spinning and synchronized with the grid frequency -- so when power is needed, operators don't have to restart the turbines.

But sometimes, physical conditions do not allow for synchronous condensing and dam operators must shut a turbine down completely until electricity is needed.

Researchers found that Bagnell Dam operators have to start and stop each turbine an average of 201 times per year. With batteries, the start-stop cycle dropped to five times per turbine annually. Since each stop costs the facility roughly $500 in lost revenue, the savings with batteries amounts to about $100,000 annually.

"[W]hile hydropower can be ramped up and down relatively quickly (by diverting water to turbines or stopping the turbines altogether), supporting the minute-by-minute changes required by today's variable energy demands causes more wear and tear on the machinery. With energy in a battery that can be dispatched almost instantaneously, the potential for hydropower dams changes immensely," PNNL said.

The new analyses will help determine whether the increased flexibility that comes with battery storage can benefit major hydroelectric projects on the Columbia River, despite significant differences.

Rey Pulido, Grant PUD's vice president of power production operations, noted Grant does not use synchronous condensing technology, but has automatic voltage regulator exciters that are used for the same purpose, so that hydropower can quickly react to intermittent renewables on the grid.

Grant PUD also spills water over its dams to aid downstream juvenile salmon and steelhead migration. Flanigan said spill does not affect the flow through the turbines, but it does affect the amount of water that can be used by the turbines to generate power during specific periods of time.

"When fish are migrating, we also use what we call ‘fish mode' for both of our dams. This fish mode limits the amount of flow we can run through the turbines and does lower our capacity at both dams," he said.

The U.S. Department of Energy's Water Power Technologies Office is funding the study.

Related Sites:
Biden-Harris Administration Releases Report Highlighting Historic and Ongoing Negative Impacts of Federal Columbia River Dams on Tribal Communities Department of Interior, 6/18/24
United States Government's Analysis of the Impacts of Federal Dams on Columbia Basin Tribes Restores the Rule of Law and Supports Immediate Action to Prevent Salmon Extinction Nez Perce Tribe, 6/18/24