How Much Water is Embedded in Energy?
A considerable amount of water is withdrawn and used for cooling in the production of energy. The United States Geological Survey's Estimated Water Use in the United States in 2015 report estimated that 41 percent of total freshwater withdrawals in the nation were for thermoelectric power generation.
The majority of water withdrawn for energy production is termed “non-consumptive use” because it eventually is returned to the same water source where it was withdrawn. However, it doesn’t necessarily return unchanged. Impacts from the cooling process include pollution and an increase in the water temperature.
Some of the water withdrawn for energy production is termed “consumptive use” because it is lost through evaporation and is not returned to the source from which it is extracted. According to a 2003 report by the National Renewable Energy Laboratory, Consumptive Water Use for U.S. Power Production, it is estimated that 2 gallons of water are consumed per kWh produced. This is based on an average of thermoelectric and hydroelectric plants in the United States. A caveat here is that 89 percent of the energy produced in the United States is thermoelectric, which uses an estimated 0.47 gallons per kWh, while hydroelectric is estimated to consume 18.0 gallons per kWh.