Drought impacts on hydroelectric power generation in the Western United States

This new report by hydrologists at Pacific Northwest National Laboratory (PNNL) suggests that the relationship between drought and hydroelectric power is more nuanced than it might seem. To get an accurate picture, PNNL hydrologists combined 20 years’ of annual power generation data from more than 600 hydroelectric power plants with historical precipitation data from eight distinct hydropower climate regions of the Western United States. Each hydropower region faces unique climatic conditions. Unique reservoir operating conditions also add complexity. Using these data, the hydrologists extrapolated hydropower generation as far back as 1900.

The researchers found that, even during the most severe droughts being observed over the last two decades, hydropower has sustained 80 percent of average power generation levels, which equates to about 150 terawatt-hours of renewable electricity—or approximately 20 percent of electricity demand across the West. This flexible power also helps to balance supply and demand in the western grid.