Utilizing a Unit Commitment and Dispatch Model to Temporally Resolve Water Use Data in the Western United States' Power Sector

The power sector is responsible for approximately one-half of the United States' annual water withdrawals and approximately 3% of its annual water consumption. The majority of this water is devoted to cooling thermoelectric power plants by means of once-through or recirculating cooled systems. Despite the large water requirements of the power sector, water conservation strategies are typically concentrated in the urban and agricultural sectors. Although national agencies such as the U.S. Geological Survey and the Energy Information Administration do publish data regarding the water use requirements of power plants, these data are often incomplete, inaccurate, and are published infrequently. Consequently, data resolving the temporal variability of water use by the power sector are largely nonexistent, making conservation strategies difficult to construct. This analysis utilizes a unit commitment and dispatch (UC&D) model to estimate water requirements of approximately 3,600 power plants in the Western Electricity Coordinating Council in the year 2020. The UC&D model used here computed generation, water consumption, and water withdrawal rates for 8,760 hourly timesteps for the projected load and generation fleet in 2020. Results suggest that the grid will become increasingly water-lean in the future, but will still require 3,600 billion gal/year in 2020, of which 7% will be consumed. The results of this study are important for developing effective water conservation strategies through the electric power grid by considering the temporal and spatial aspects of the water supply and the water needs of the grid.