A System-Level Generic Model of Water Use at Power Plants and its Application to Regional Water Use Estimation

Abstract

The withdrawal and consumption of water at electricity generation plants, mainly for cooling purposes, is a significant component of the energy water nexus in the US. The existing field data on US power plant water use, however, is of limited granularity and poor quality, hampering efforts to track industry trends and project future scenarios. Furthermore, there is a need for a common quantitative framework on which to evaluate the potential of the many technologies that have been proposed to reduce water use at power plants. To address these deficiencies, we have created a system-level generic model (S-GEM) of water use at power plants that applies to fossil, nuclear, geothermal and solar thermal plants, using either steam or combined cycles. The S-GEM is a computationally inexpensive analytical model that approximately reflects the physics of the key processes involved and requires a small number of input parameters; the outputs are water withdrawal and consumption intensity in liters per kilowatt-hour. Data from multiple sources are combined to characterize value distributions of S-GEM input parameters across the US, resulting in refined estimates of water use with quantified uncertainties. These estimates are then validated against typical values from the literature and against an existing field data set. By adjusting S-GEM input values or value distributions, any number of hypothetical scenarios can be rapidly evaluated. As an example, we focus here on technology evaluation, expressing proposed technological improvements in terms of S-GEM input parameters, then comparing their projected effects on overall water withdrawal and consumption intensities.