Assessing the Vulnerability of Western U.S. Grid Operations to Water Availability

Recent research finds a 3 percent chance that 6 percent or more of energy demand could go unmet in summer.

The Science

A recent study estimated electricity grid operations over the western United States during 30 years of water availability conditions to isolate and characterize critical droughts. The researchers demonstrated and quantified the interdependency between drought severity and impact on grid operations using reliability and economics metrics (unserved energy, capacity reserve margin, and production cost). They also isolated regional drought patterns that lead to higher vulnerability.

The Impact

Assessments of electric infrastructure vulnerability are typically performed for a baseline water year or a specific period of drought. This research describes a more holistic approach for estimating the distribution of stress on the grid by simulating electricity grid operations over the western United States during 30 years of water availability conditions.


Droughts reduce both hydropower generation and the generation capacity of thermoelectric power plants. When droughts coincide with high summer temperatures, when energy demand is typically highest, the electric grid becomes stressed and grid operations must deviate from normal to avoid unserved energy (i.e., blackouts and brownouts). Using a combination of models and a new grid-centric metric for drought severity, scientists from the Department of Energy’s Pacific Northwest National Laboratory demonstrated and quantified the impact of simulated historical droughts on grid operations. They also identified regional drought patterns that are associated with higher grid vulnerability and estimated the western United States’ grid stress distribution as a function of interannual variability in regional water availability. They “softly” coupled an integrated water model (climate, hydrology, river routing, water resources management, and socioeconomic water demand models) to an electricity production cost model and simulated August grid operations for 30 years of simulated water availability under historical conditions. The results indicate a clear correlation between annual water availability and grid vulnerability (i.e., unmet electricity services) during August, and show how better knowledge of the electricity system’s risk exposure due to water constraints could improve power system planning. Deeper understanding of the impacts of regional variability in water availability on the grid’s reliability could help motivate the development of improved interdependency analysis and trade-off strategies in the context of climate mitigation and adaptation scenarios.

Principal Investigator(s)

Ian Kraucunas
Pacific Northwest National Laboratory


This work was supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research as part of the Integrated Assessment Research program. Initial model development and data analyses were supported by the Laboratory Directed Research and Development Program at Pacific Northwest National Laboratory.


Voisin, N., M. Kintner-Meyer, J. Dirks, R. Skaggs, D. Wu, T. Nguyen, Y. Xie, and M. Hejazi. 2016. “Vulnerability of the U.S. Western Electric Grid to Hydro-Climatological Conditions: How Bad Can It Get?” Energy 115,1-12. DOI:10.1016/j.energy.2016.08.059.