The USGS Water Science School
Producing electrical power is one of the largest uses of water in the United States. In 2000, 195,000 million gallons of water each day were used to produce electricity (excluding hydroelectric power).
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 could be harmed. So, the used water must first be cooled.
This picture shows a power plant that uses coal to generate electricity. According to the Energy Information Agency, about 57 percent of the Nation's total power is produced by burning coal. Those four huge towers are the cooling towers. Hot water is cooled by evaporation as it is sprayed into the air inside these towers.