|Fig. 1: Chart of 1995 U.S. Water Consumption by Sector. (Source: J. H. Styles III, after T. Feeley et al. )|
As of 2013, thermoelectric electricity generation accounted for roughly 3% of freshwater consumption the United States.  Most power plants operate under the simple principle of generating electricity by converting boiling water into steam, which can turn a turbine that is connected to a generator to produce power.  Cooling systems are required in these power plants to turn the steam back into water so it can continue operating. These cooling systems requires the consumption of additional water to circulate throughout the plant to condense the steam back into water through heat absorption.  Nuclear power plants operate similarly and are typically built near lakes or rivers to facilitate water withdrawals and consumption. 
As of 2015, nuclear energy accounted for roughly 20% (797.2bn KwH) of total U.S. electricity generation in 2015.  With Nuclear Energy consuming roughly 400 gallons of water per megawatt-hour, 320 billion gallons of water were consumed by United States nuclear power plant electricity generation in 2015.  To put that into perspective, that is enough water freshwater to fill over 480,000 Olympic pools. In addition, in order to satisfy the energy consumption needs of the global population in 2015, nuclear power plants would have had to consume a volume of water equivalent to roughly 1.5 times that of Lake Tahoe. While that might seem like a large number, nuclear power plant water consumption dwarfs in comparison to other consumer sectors.
As seen in Fig. 1, residential water consumption is more than double that of electricity generation as a whole and irrigation accounts for a vast majority of total water consumption in the United States. Moreover, relative to methods of electricity generation, nuclear consumes relatively similar quantities of water or less. Coal, on average, consumes roughly the same amount of water per kilowatt-hour as nuclear, while it does very more heavily depending on the type and age of the individual power plant. Nuclear is an extremely viable resource in regard to water consumption with only wind and photovoltaic electricity generation as its major competitors who are more viable from a water consumption perspective. While there are proposed alternatives to wet-cooling systems that could further minimize nuclear power plant water consumption, they lead to considerable performance drop-offs and do not present a significant enough benefit to warrant that tradeoff.  Although Nuclear energy is seen as extremely viable in regard to water use, there are issues that lie in its withdrawals rather than its consumption.
|Fig. 2: Chart of 2000 U.S. Water Usage by Sector. (Source: J. H. Styles III, after T. Feeley et al. )|
While electricity accounted for only 3.3% of U.S. freshwater consumption in 2013, it has accounted for as high as roughly 40% of all freshwater withdrawals dating back to 2000 as seen in Fig. 2, which makes them susceptible to drought-related shutdowns or breakdowns if the lake or river water supply experiences subpar rainfall for extended periods.  Furthermore, this means that nuclear power plants are susceptible to changing climate conditions. For example, in 2007 a drought in the southeastern United States led to the shutdown of many thermal electricity generation plants, including one nuclear power plant, which had to shut down its operations due to lack of water which caused high discharge temperatures. As such, integrated environmental and infrastructural planning efforts need to take place in order to identify potential freshwater constraints when building a new nuclear facility and to minimize the effects of water- related shutdowns.
While Nuclear Power plants are not as water-friendly as wind or photovoltaic solar electricity generation, they are a viable resource for the future of electricity generation as they are competitive with nearly all other generation methods and have numerous benefits over others concerning other forms of pollution. The Nuclear Energy Institute suggests that a majority of future nuclear power plants should be built at coastal locations that can utilize ocean saltwater to minimize the probability of drought-related shutdowns and to provide the opportunity for the construction of desalination plants to offset their freshwater consumption.  This trend would further improve perception of nuclear power plant water withdrawal and consumption and make it the most viable thermal electricity generation method from a sustainability perspective.
© JohnHenry Styles III. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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