Oak Ridge Lab Report Helps Hydropower Operators Prepare for Climate Change

by Paul Ciampoli
APPA News Director
October 8, 2022

A new report from the Department of Energy’s Oak Ridge National Laboratory (ORNL) aims to provide hydropower operators data that will better enable them to plan for changing climate conditions.

The data collected and analyzed in the report can aid operators in shifting operational schedules and seasonal water use as part of an overall mitigation strategy in the face of changing climate conditions and reduced water availability, the report’s authors said.

Among other findings, the report projects that earlier-than-expected snowmelt season in the western United States is likely to impact water runoff, resulting in less water for hydropower generation in the summer months, just as energy demand grows. In addition, Increased evaporation because of rising temperatures is also putting a strain on water needed for flood control, navigation, municipal water supplies and industrial and agricultural use.

The report also found that, except for part of summer and fall, there is a persistent increase in projected precipitation, especially in the winter, resulting in a net annual precipitation increase of up to 8 percent.

On a seasonal basis, the report found that winter and spring runoff are generally projected to increase across the conterminous United States while summer runoff is projected to decrease for many parts of the country, especially in the West and the South, resulting in a shift in the timing and seasonality of the water availability.

That effect may be magnified in the Southwest and Southeast because hydropower reservoirs in those regions have less storage capacity than federal hydropower reservoirs under the control of the Bonneville Power Administration and the Western Area Power Administration, the report found.

As a result, on a seasonal basis, most models project increasing hydropower generation in winter and spring, and decreasing generation in summer and fall caused by earlier snowmelt and changing runoff, the report said.

The combination of declining winter heating load and increasing hydropower generation suggests that federal hydropower surpluses are likely during the winter months, the reports’ authors said. Thus, they said, the ability to shift water from winter to summer months and to maximize the revenue from winter surpluses to compensate for potential increased power purchase requirements in the summer will be valuable for all power marketing administrations.

The ORNL researchers used downscaled global climate projections to simulate future hydrologic conditions at 132 federal hydropower facilities across the United States to compile the report.

In order to provide more hydropower stakeholders with the tools and data to plan for climate change impacts, the Department of Energy said it is extending its research to non-federal hydropower facilities, whose operators may not have the resources to study and address these challenges.