Water is used in two primary ways for electricity generation:
- To create steam to power the turbines generating electricity
- Thermodynamic cooling of the power plant (condense the steam back into water, etc.)
We rely on the heat from energy sources such as coal, natural gas, nuclear, etc. to create power. How does this work? The heat from the particular fuel type generates steam that is then used to power the turbine, generating electricity that can then be sent to the grid. Once the steam is used it is cooled back down to either be released back into its original source (river, lake, etc.) or to be reused. Water is used to condense the steam in a term referred to as a steam loop.1Stillwell , A., King , C., Webber , M., Duncan , I., & Hardberger, A. (2009, April). Energy‐Water Nexus in Texas. http://texaslivingwaters.org/wp-content/uploads/2013/04/energy-and-water-in-tx09.pdf Different power plants use different quantities of water for cooling purposes. For example, cooling a coal-fired power plant requires different quantities of water compared to a nuclear power plant.
According to the Energy Information Administration (EIA), 40% of total water withdrawal in the country accounts for cooling technologies in electrical power generation.2U.S. Energy Information Administration. (n.d.). U.S. Energy Information Administration – EIA – Independent Statistics and Analysis. Some U.S. electricity generating plants use dry cooling – Today in Energy – U.S. Energy Information Administration (EIA). https://www.eia.gov/todayinenergy/detail.php?id=36773 There are ways to reduce water consumption such as recirculating the condensed steam back into the steam generator source or reducing consumption from the original source. This process is referred to as a closed steam loop.3Stillwell , A., King , C., Webber , M., Duncan , I., & Hardberger, A. (2009, April). Energy‐Water Nexus in Texas. http://texaslivingwaters.org/wp-content/uploads/2013/04/energy-and-water-in-tx09.pdf There are also technologies that use dry cooling, which entails using ambient air for cooling the steam once it is used to power the turbines instead of water. Hybrid cooling systems can also be used, including a mix of dry cooling and water consumption for cooling purposes.4U.S. Energy Information Administration. (n.d.). U.S. Energy Information Administration – EIA – Independent Statistics and Analysis. Some U.S. electricity generating plants use dry cooling – Today in Energy – U.S. Energy Information Administration (EIA). https://www.eia.gov/todayinenergy/detail.php?id=36773
Image Credits: Photo courtesy of Siemens Germany; Photo courtesy of of Siemens Germany by Christian Kuhna; Photo courtesy of Larry D. Moore; Larry D. Moore