Validating and comparing energy estimation methods at water resource recovery facilities

Water resource recovery facilities play a crucial role in the water–energy nexus, consuming a substantial amount of energy in the United States. Growing treatment volumes and more stringent water quality standards are expected to increase the amount of energy needed to treat wastewater, but accurately estimating energy consumption and potential remains challenging due to variability in scale, treatment methods, and effluent standards. In this study, we used publicly available data to evaluate the accuracy of methods for estimating energy consumption, then quantified uncertainty based on key factors like flow rate, treatment level, and geographic location. To validate methods, we estimated energy consumption at the facility level, then compared estimates to self-reported data from utilities in major U.S. cities. We found that methods based on effluent treatment level and flow rate performed well for estimating electricity consumption, and process models of treatment trains were accurate relative to other methods for estimating total energy consumption. Applying the evaluated methods to a national inventory of treatment facilities, we estimate that annual energy consumption ranged from 50,900 to 77,100 TJ in 2012 and will increase to between 81,100 and 123,000 TJ in 2042. By quantifying the variability of existing estimation methods and highlighting their advantages and disadvantages, this work enables more data-driven water–energy management in the future.