GEF

Unit 3  |  Water Use and Human Water Systems 83 Electricity generation from coal, natural gas, or nuclear energy requires enormous volumes of water to cool the steam that drives turbines. For the most part, this is non-consumptive use, as this water is normally returned directly to the water body it was drawn from. However, in older plants the water is released to the environment at a much higher temperature, which can result in thermal pollution . The warmwater holds lower amounts of dis- solved oxygen than cool water, harming a wide array of species after it is introduced back into ecosystems. Some species, such as manatees, actually benefit fromwarmer water and seek out power plant water discharges during winter months. Mantee Viewing Center next to a power plant in Tampa, FL Encouragingly, the water efficiency of electricity production improved dramatically in recent decades. The amount of water used to produce one kilowatt of electricity has decreased from sixty-three gallons in 1950 to twenty-one gallons in 2000. In many cases however, electricity generation places demands on water resources that are proving challenging to meet. During drought conditions that are expected to worsen with THERMAL POLLUTION Raised water temperature due to power generation or other industrial activity. KILOWATT A measurement of energy consumption that is used by electric utility companies for billing energy to consumers.