Production of electrical power results in one of the largest uses of water in the United States and worldwide. Water for thermoelectric power is used in generating electricity with steam-driven turbine generators. In 2000, about 195,000 million gallons of water each day (Mgal/d) were used to produce electricity (excluding hydroelectric power). Surface water was the source for more than 99 percent of total thermoelectric-power withdrawals. In coastal areas, the use of saline water instead of freshwater expands the overall available water supply. Saline withdrawals from surface water sources accounted for 96 percent of the National total saline withdrawals. Thermoelectric-power withdrawals accounted for 48 percent of total water use, 39 percent of total freshwater withdrawals for all categories, and 52 percent of fresh surface-water withdrawals.
One of the main uses of water in the power industry is to cool the power-producing equipment. Water used for this purpose does cool the equipment, but at the same time, the hot equipment heats up the cooling water! Overly hot water cannot be released back into the environment -- fish downstream from a power plant releasing the hot water would get very upset. So, the used water must first be cooled. One way to do this is to build very large cooling towers and to spray the water inside the towers. Evaporation occurs and water is cooled. That is why large power-production facilities are often located near rivers, lakes, and the ocean.
For 2000, withdrawals were an estimated 137,000 million gallons per day (Mgal/d), or 153,000 thousand acre-feet per year. Irrigation withdrawals were 40 percent of total freshwater withdrawals and 65 percent of total freshwater withdrawals for all categories excluding thermo-electric power. Surface water accounted for 58 percent of the total irrigation withdrawals. About 61,900 thousand acres were irrigated in 2000. Of this total acreage, about 29,400 thousand acres were irrigated with surface (flood) systems; 28,300 thousand acres with sprinkler systems; and 4,180 thousand acres with micro-irrigation systems. Application rates were calculated by dividing total withdrawals by irrigated acres. The average application rate was 2.48 acre-feet per acre for the United States.
In the Midwestern states where a lot of power is needed for industries and large populations, thermoelectric-power plants make use of the abundant freshwater supplies of the Great Lakes and large rivers.
[d] - Data for this chart are available.
Thermoelectric power has been the category with the largest water withdrawals since 1965, and for 2000 comprised 48 percent of total withdrawals. The largest total and fresh and saline surface-water withdrawals were during 1980. Withdrawals by thermoelectric-power plants increased from 40,000 Mgal/d during 1950 to 210,000 Mgal/d during 1980. Withdrawals for thermoelectric power declined and then stabilized since 1980; the total withdrawal of 195,000 Mgal/d for 2000 is the same as the total withdrawal for 1990.
Sources and more information
Estimated Use of Water in the United States in 2000, USGS Circular 1268:
• Thermoelectric-power water use, 2000: Summary | Data table, by State | National map
U.S. Department of the Interior | U.S. Geological Survey
URL: http://ga.water.usgs.gov/edu/wupt.html
Page Contact Information: Howard Perlman
Page Last Modified: Friday, 07-Nov-2008 15:47:15 EST
