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Hydropower – More than megawatts

The latest data show hydropower represents 6.6% of all electricity generated and 38% of electricity from renewables produced in the United States. Pictured is the Red Rock Hydroelectric Project in Marion County, Iowa. Credit: Missouri River Energy Services


A new Department of Energy report produced by Oak Ridge National Laboratory details national and international trends in hydropower, including the role waterpower plays in enhancing the flexibility and resilience of the power grid.

Much of this flexibility stems from pumped storage hydropower, or PSH, where reservoirs store water at higher elevations for on-demand electricity generation. PSH contributes 93% of grid-scale energy storage – more than batteries and all other technologies combined.

Interest has grown in PSH as a least-cost option for energy storage applications requiring long discharge cycles of four to 16 hours, with the project pipeline doubling over the last five years and new projects being explored in 21 states. 

“Our analysis found that hydropower punches above its weight in terms of providing ancillary services like frequency regulation and reserves compared to its percentage of installed capacity,” said ORNL’s Rocio Uria-Martinez. “Hydropower’s dispatchable nature provides critical benefits in filling gaps in power supply and addressing peak demand.”