Pumped Hydro Storage: A Path Forward for Harnessing Renewables

Last summer, we wrote about the bright future ahead for energy storage, shining a light on pumped hydro technology. Lithium-ion batteries tend to get more screen time, but pumped-hydro is undergoing a renaissance in its appeal. There are currently 24 permitted and operational pumped storage facilities here in the U.S. with a total capacity of 16,500 megawatts of electricity – most of which were authorized 30 years ago. The Federal Energy Regulatory Commission (FERC) has received a surge of applications for new pumped storage projects, however, and we expect this technology to play a large role in integrating renewable energy.

For example, the FERC has recently accepted an application from developer Daybreak Power for a preliminary permit for its proposed Navajo Energy Station. The project is still in its infancy, but it is definitely promising. The Daybreak project would utilize the electric transmission line infrastructure previously used by the currently closed Navajo Generating Station coal fired power station. If built, the project would generate 2230 MW of electricity with 10 hours of energy storage qualifying it as a long duration storage facility.

Pumped storage works in two stages using an upper and lower reservoir. When there is excess electricity, water is pumped up to the upper reservoir for storage. When electricity demand is tight, or at its peak, water from the upper reservoir is released through a hydropower turbine producing power. Such a pumped storage facility at Raccoon Mountain in Tennessee, for example, is the largest single hydroelectric project in the Tennessee Valley Authority system. The FERC has also issued construction permits for other facilities like the Eagle Mountain Pumped Storage Project in Southern California.

However, Daybreak will be slightly different than these two facilities. Unlike these pumped hydro plants, which use some of the energy generated while the water is released to re-charge the pump for the next use, Navajo Energy Station will use solar and wind energy to pump water to the upper reservoir.

The project comes with a $3.6 billion price tag which might be a potential roadblock, but Daybreak Power is looking at multiple options for financing, including power purchase contracts and of course there’s also a possibility that grid operators may choose to invest in the project. Pumped hydro is good investment. A recent study by the U.S. Department of Energy (DOE) found that pumped hydro’s cost is currently half of the projected 2025 cost of lithium-ion batteries. The facilities are expected to have an 80-120 year lifespan, making them well worth the large upfront investment.

While it isn’t always talked about enough, pumped hydro storage is a proven energy resource that will help to integrate more renewables into the Bulk Electric System while ensuring standby power is available during times of no wind or sunlight. We’ll be watching closely to see how the future of projects such as the Navajo Energy Station play out.