Access to water worldwide is expected to become a major issue in the coming decades, leading to potential wars over rights according to many reports. A shift in rainfall patterns will make obtaining water even harder in many regions of the globe. Currently many towns and cities are already experiencing extreme droughts, causing water to be conserved. Now a recent report brings in the question how water conservation may be directly tied to electricity consumption.
A recent report published by the River Network group based in Portland, Oregon focused on the use of water in generating electricity. The report is titled The Water Footprint of Electricity and determined that massive amounts of water are being used in generating electricity across the United States, a scenario they indicate needs to be changed in order to reduce pollution and increase access to water.
According to a U.S. Geological Survey from 2005, fifty-three percent of fresh, surface water used in the U.S. could be attributed to the electricity process, such as for use cooling coal plants. Other reports indicate that the use of water may actually be growing in the electricity field. Overall, the River Network determined as of 2009 that on average 41.6 gallons of water are used for each kilowatt hour of electricity generated.
According to the report, this amount of water used per kilowatt hour would indicate that the average U.S. household uses 39,829 gallons of water each month for electricity. The majority of this footprint is due to hydroelectric power, however, there is considerable contribution from other forms of common electricity sources in the U.S.. Coal, nuclear power and natural gas all contribute greatly to the water footprint according to the report.
River Network reported the amount of water each electricity source withdrew from the environment on average and how much water the process consumed. The difference between the two indicate that this water was returned to rivers and streams across the country. For coal, 16,052 gallons are withdrawn per megawatt hour of energy generation, while 692 gallons were consumed and likely turned to steam. Nuclear energy withdraws 14,881 gallons per megawatt hour and 572 gallons are consumed. Natural gas is also a considerable consumer of water, withdrawing 6,484 gallons per megawatt hour and consuming 172 gallons.
The report indicates that the push to use renewable energies will also lessen the overall water footprint of electricity generation. Declines in freshwater use by power plants could prove pivotal in coming years as water becomes potentially more scarce. Wind and PV solar energy appear to be the least water dependent, only withdrawing between zero and 231 gallons per megawatt hour of energy.
In addition to the growing concern of diminishing water resources, the group also indicated other problems with the use of water in generating electricity. Thermal pollution was one issue the group felt was extremely problematic. Thermal pollution is when a process or addition to water changes the ambient water temperature of the water. Changes such as this in rives and streams could directly impact many aquatic species which require a certain range of temperature in order to survive. Subsequently, the death of species and algae blooms are considered major risks of power plants using water in their processes.
In addition, pollutants directly entering waterways from power plants are also a concern. The water may come into contact pollutants via the cooling process or other processes used by power plants. These pollutants may then accumulate in the rivers in which they are returned. The Union of Concerned Scientists recently indicated that 120 watersheds in the U.S. are vulnerable with power plants largely contributing.