Evaporative cooling systems have been criticized for their water use and acclaimed for their low energy consumption, especially when compared to typical cooling systems. In order to determine the overall effectiveness of cooling systems, both water and energy need to be considered; however, data are needed to compare the amount of energy used at the site to the amount of water used at the power plant. A study of power plants and their water consumption was completed to effectively analyze evaporative cooling systems.

In thermoelectric plants, 0.47 gallons (1.8 L) of fresh water is evaporated per kilowatt-hour (kWh) of electricity consumed at the point of end-use. Hydroelectric plants evaporate an average of 18 gallons (68 L) of fresh water per kWh used by the consumer. The national weighted average is 2.0 gallons (7.6 L) of evaporated water per kWh of electricity consumed at the end-use. From this information, different types of building cooling systems can be compared for relative water consumption.

Units: Dual