The US Department of Energy’s Oak Ridge National Laboratory has provided hydroelectric operators with new data to better prepare for extreme weather events and shifts in seasonal energy demand caused by climate change.
For the new report, ORNL researchers used scaled-down global climate projections to simulate future hydrological conditions at 132 federal hydroelectric power plants across the United States. The resulting projections will enable hydropower operators and policymakers to plan for changing climate conditions and reduced water availability by shifting their operational schedules and water use each season as part of an overall mitigation strategy.
“The intensification of future extreme events, including floods and droughts, is one of the most critical issues threatening the resilience of US hydropower systems and infrastructure,” said Shih-Chieh Kao, hydropower program manager at ORNL. “This new normal requires us to think differently about current operating practices to adapt to a changing climate.”
In addition to extreme events, a growing conflict between water availability and energy demand is another challenge for hydropower operators. An earlier than expected snowmelt season in the western United States will likely impact water runoff. This can lead to less water being available for hydroelectric power generation in the summer months when the demand for energy increases. Increased evaporation due to rising temperatures is also putting a strain on the water needed for flood control, shipping, municipal water supplies, and industrial and agricultural uses.
A better understanding of these changes is important for future energy planning. Hydropower provides 35% of renewable energy and nearly 7% of all electricity generated in the US
ORNL worked with the DOE’s Water Power Technologies Office and other federal agencies, building on two rounds of previous hydroclimate assessments conducted over the past 10 years. The study focused exclusively on federal hydroelectric power plants, which account for about half of the total US hydroelectric capacity and provide a variety of non-utility services to the community. Power marketed by DOE Power Marketing Administrations is sold at these facilities primarily to public utilities and rural electric cooperatives in 33 states.
The study was based on regularly updated global climate projections from the Coupled Model Intercomparison Project, which supports regular studies by the Intergovernmental Panel on Climate Change. However, to optimally downscale the climate signals for each watershed, the researchers had to consider features unique to each facility and site.
From 2010 to 2013, ORNL researchers collected a variety of data on observed and simulated climate events, historical generation of hydroelectric power plants, and watershed and land surface features unique to each region. The research team used this data to develop an assessment framework that could forecast water availability for hydroelectric operations by simulating a variety of hydrological conditions, including annual and seasonal air temperatures, precipitation, runoff from melting snow or rain, and drought levels.
From 2014 to 2017, the team focused on how month-to-month and seasonal climate changes might affect hydroelectric power generation. This extension provided key data and forecasts that enabled hydropower operators to assess current operational practices with a focus on climate adaptation.
In the most recent iteration, from 2018 to 2022, ORNL developed a multimodal assessment framework to better show uncertainties and variability in future hydropower projections in the regions. Pacific Northwest National Laboratory and Texas A&M University collaborated with ORNL on this phase of the project.
Using a range of numerical models and statistical methods, researchers downscaled global climate change signals into future hydrological and hydropower projections at each watershed. Each assessment included simulations of future power flow, hydropower operation, and reservoir evaporation. Based on these simulations, researchers also estimated future energy needs, which will be affected by changing climate conditions.
Balancing water availability through water management
To maintain the benefits of hydropower as a renewable energy source, flexibility will be key and these models provide a federal roadmap for long-term planning.
To provide more hydropower stakeholders with the tools and data they need to plan for climate change impacts, the DOE is expanding its research to include non-governmental hydropower plants whose operators may not have the resources to study and address these challenges .
“The climate system is complex,” Kao said, “but we can now integrate increasingly accurate predictive models to understand potential shifts in climate extremes and determine what can be done to mitigate those changes.”
The study was directed by the SECURE Water Act of 2009 and supported by the Water Power Technologies Office in the DOE Office of Energy Efficiency and Renewable Energy.
UT-Battelle directs Oak Ridge National Laboratory for the DOE Office of Science, the largest single funder of basic research in the physical sciences in the United States. The DOE’s Office of Science works to address some of the most pressing challenges of our time. Visit energy.gov/science for more information. – Mimi McHale
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