Environmental impacts of desalination
Desalination is a process that removes minerals from salty water, enabling its use for drinking and irrigation, particularly in areas where fresh water is scarce. While over eighty countries face challenges in providing sufficient potable water, desalination presents a potential solution, especially in coastal regions with abundant seawater. However, the process comes with notable environmental concerns. It typically requires significant energy resources, often derived from fossil fuels, contributing to carbon dioxide emissions and global warming. Additionally, the intake of seawater can result in the death of marine organisms, such as fish larvae and plankton. The disposal of concentrated brine, a byproduct of desalination, can alter the local marine environment unless managed carefully. Some plants implement strategies to mitigate these effects by mixing brine with cooler seawater or dispersing it over larger areas. While desalination serves as a critical water source for many, understanding its environmental impacts is essential for balancing water needs with ecological health.
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Environmental impacts of desalination
DEFINITION: Process of removing minerals from salty water to make the water fit for humans to drink or for use in irrigation
More than eighty countries around the world have problems obtaining sufficient potable water to serve their populations. Desalination offers a way to provide water to people living where sources of fresh water are scarce, but the process is associated with a number of negative environmental impacts.
Water is abundant in the world, but only about 3 percent of all water is potable—that is, fit for humans to drink. It is possible to remove salts from seawater or to make potable water, but the desalination process uses large amounts of energy. The costs of desalination depend on the type of feed water (seawater or brackish water) and its temperature, the method being used (membrane filtration, distillation, or exchange), the type of energy used (nuclear, petroleum, or solar), and the amount of water to be processed. Producing through desalination is expensive compared with taking potable water out of the ground or from streams, ranging from about 50 cents to 70 cents per cubic meter of potable water produced (1 cubic meter is equal to about 35 cubic feet, or 264 gallons).
The nations that have established large desalination plants are bordered by oceans, have little potable water on their land, and have large amounts of cheap energy, such as petroleum, available for use. Middle Eastern countries produce the greatest amounts of potable water produced in the world through the desalination of seawater. Up to 49 billion liters (13 billion gallons) of potable water are produced each day by more than fifteen thousand desalination plants located in such places as North Africa, Saudi Arabia, the United Arab Emirates, Japan, Australia, and the United States.
The largest desalination plant in the world is Ras Al Khair in Saudi Arabia, which can produce 1,036,000 million cubic meters of water per day. The plant is a hybrid project that uses thermal multistage flash (MSF) and reverse osmosis (RO) technologies. Among the large desalination plants in the United States are one in San Diego, California, and one in San Antonio, Texas. While only about two hundred desalination plants are in the United States, most are in California, Florida, and Texas.
Several negative environmental impacts are associated with the operation of desalination plants. For one thing, the plants use high amounts of energy, usually electricity generated by the burning of fossil fuels, a process that produces carbon dioxide, one of the gases associated with global warming. Desalination plants can also have more direct effects on the environment. The intake of seawater into a plant can kill organisms such as fish larvae and plankton, and the disposal into the ocean of warm residual waters very high in after processing may harm some animals. Plants can be designed to avoid the latter problem, however. The warm, concentrated brine waters can be mixed with cooler and less concentrated waters so that the water returned to the ocean is more similar in temperature and to seawater, or the concentrated brine water can be dispersed over a large area in the ocean so that it changes the seawater composition and temperature very little.
Bibliography
Chiras, Daniel D. “Water Resources: Preserving Our Liquid Assets and Protecting Aquatic Ecosystems.” In Environmental Science. 8th ed. Sudbury, Mass.: Jones and Bartlett, 2010.
Chu, Jennifer. "Desalination System Could Produce Freshwater That Is Cheaper Than Tapwater." MIT News, 27 Sept. 2023, news.mit.edu/2023/desalination-system-could-produce-freshwater-cheaper-0927. Accessed 16 July 2024.
Eltawil, Mohamed A., Zhao Zhengming, and Liqiang Yuan. “A Review of Renewable Energy Technologies Integrated with Desalination Systems.” Renewable and Sustainable Energy Review 13 (2009): 2245-2262.
Escobar, Isabel, and Andrea Schäfer, eds. Sustainable Water for the Future: Water Recycling Versus Desalination. Oxford, England: Elsevier, 2010.
Karagiannis, Ioannis C., and Petros G. Soldatos. “Water Desalination Cost Literature: Review and Assessment.” Desalination 223 (2008): 448-456.
"Largest Desalination Plants." Aqua Tech, 19 Apr. 2021, www.aquatechtrade.com/news/desalination/worlds-largest-desalination-plants. Accessed 16 July 2024.
National Research Council. Desalination: A National Perspective. Washington, D.C.: National Academies Press, 2008.