National Study Finds Overall Hydropower Generation May Increase Despite Regional and Seasonal Changes in Climate Conditions

Hydropower facilities help electricity grids across the United States remain reliable and stable, ensuring homes and businesses have power when they need it. Currently, hydropower generates 27% of U.S. utility-scale renewable electricity and nearly 6% of the nation’s total utility-scale electricity. However, changing climate conditions, such as shifting precipitation patterns, earlier snowmelt, and more frequent extreme events, could affect the availability of water and how it moves through a watershed (a land area that channels water to rivers, lakes, and oceans). This is particularly important for managing major reservoirs, where water serves multiple purposes, such as hydropower generation and drinking water supplies.

To help hydropower owners and operators ensure stable and reliable hydropower generation, researchers from Pacific Northwest National Laboratory and Oak Ridge National Laboratory conducted a national study to evaluate how climate change may affect future hydropower production across the contiguous United States. This research, outlined in Environmental Research Letters, represents one of the largest climate change-informed U.S. hydropower modeling efforts to date with data available for 1,544 federal and non-federal hydropower facilities. Collectively, these facilities can generate 86 gigawatts of electricity, enough to power nearly 30 million homes. 

The study reveals that, on average, U.S. hydropower generation may increase 5% by 2039 and 10% by 2059 as climate change alters the country’s weather patterns and waterways. However, increases will vary regionally and seasonally, and severe water level reductions could impact hydropower generation as the risk of regional droughts also increases. 

The study expands on findings from three assessments on the effects of climate change on federal hydropower as mandated in Section 9505 of the SECURE Water Act of 2009, which directed the U.S. Department of Energy to examine the effects of climate change on federal hydropower facilities. 

The new study leverages 96 different hydroclimate projection frameworks to cover more than 85% of total hydropower capacity across the contiguous United States. Its hydropower generation projections are based on downscaled and bias-corrected future climate projections. These projections are integrated with hydrologic models, which estimate how watersheds respond to environmental changes, to simulate hydropower operation and generation. All research is highly collaborative with the four federal Power Marketing Administrations.  

The study further models the compounding effects of hydrologic changes over time, the physical characteristics of each hydropower facility, and the operational constraints and objectives of each facility. At each step of this modeling chain, multiple approaches were used to account for variability in model selection and parameters. The study assumed that all physical and operational characteristics would remain fixed, and that no additional facilities would be constructed or decommissioned.

According to the study, impacts from climate change in one part of the country could vary from impacts in another part throughout the year. The West, for example, could see decreasing hydropower generation in the summer and fall as earlier snowmelt increases water availability in late winter and spring. Meanwhile, the East could see increased generation in the fall due to heavier rain.

Seasonal forecasting further shows increased generation in the North and decreased generation in the South. These collective findings highlight much greater uncertainty about hydropower generation in California, the Southwest, and the Southeast when compared to the Pacific Northwest, Northeast, Mid-Atlantic, and Midwest. Some of this uncertainty can be attributed to changing snowpack and precipitation events, including winter atmospheric rivers in California and the North American Monsoon in the Southwest. Similar, but slightly narrower, uncertainty exists around fall and winter generation in the Southeast.

The study underscores the need to continue monitoring changing seasonal patterns to meet future water and energy demands. The research team plans to continue developing the dataset to provide regional utilities and power system operators with consistent data to plan drought scenarios, design long-duration storage, and evaluate infrastructure upgrades to respond to increasing weather variability. A fourth assessment on the effects of climate change on federal hydropower facilities is also underway.

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