ENERGY SECURITYStrengthening the Grid’s ‘Backbone’ with Hydropower

By Michael Matz

Three recent studies by the U.S. Department of Energy’s (DOE) Argonne National Laboratory advance the role of hydropower in driving the clean energy transition. The research explored hydropower’s potential in Alaska, its value to grid operations and its optimal design. DOE’s Water Power Technologies Office (WPTO) recognized this work in its 2022-2023 Accomplishments Report — a compilation of some of the most impactful WPTO-funded hydropower research. The three studies were supported by WPTO’s HydroWIRES Initiative.

Why Hydropower Matters
Rapid deployment of wind and solar energy often makes headlines in news coverage of the clean energy transition — and rightly so. These low-cost, zero-carbon renewable energy sources are helping the U.S. meet its ambitious goal to build a clean power system by 2035.

While less often in the headlines, hydropower — the world’s largest source of renewable energy — is equally important for transitioning electric grids to clean energy. It can support the integration of wind and solar generation in several ways. When the output of these variable energy resources is not enough to meet demand, conventional hydropower reservoirs can release more water to increase energy generation. This helps balance the grid when the wind doesn’t blow or the sun doesn’t shine.

Another type of hydropower facility known as pumped storage hydropower (PSH) is the most mature grid-scale storage technology. During low-demand periods, these facilities use excess solar and wind electricity to pump water from a lower to an upper reservoir. This process stores the energy. Later, when demand is greater, water released by the upper reservoir flows through a turbine to the lower reservoir, generating electricity. According to the DOE, these giant ​“water batteries” accounted for 96% of utility-scale energy storage capacity in the U.S. in 2022.

PSH’s proven ability to provide long-duration energy storage — more than eight hours — supports grid reliability and resilience. This becomes particularly important during extreme weather when the grid may need days or even weeks of backup energy.

“We need a huge amount of energy storage to reliably operate grids with a high penetration of wind and solar,” said Vladimir Koritarov, director of DOE’s Argonne National Laboratory’s Center for Energy, Environmental and Economic Systems Analysis. ​“A mix of various storage technologies, including hydropower and batteries, will be necessary to perform diverse functions.”