Water consumption from hydroelectricity in the United States

Understanding the relationship between water and energy systems is important for effective management of both resources. Improved data availability has made more comprehensive modeling of hydropower and its water use possible, even as droughts and climate change have made questions about reservoir evaporation responsiveness more timely. This work makes three main contributions: first, it presents national and regional estimates of gross evaporation and evaporation net of evapotranspiration from local land cover (“net evaporation”) for U.S. hydroelectricity, arguing that net evaporation is more consistent with other measures of energy-related water intensity; second, it introduces and validates a method for estimating system-wide evaporation based on primary purpose allocation that reduces data requirements by two orders of magnitude; and third, it makes available for public use a full Penman-Monteith model with multiple built-in sensitivity analyses. Based on this model, the U.S. hydropower system consumes an estimated average of 1.7 m3 of net freshwater per GJ electricity produced (11 m3/GJ gross).