Abstract
Global water demand is rising, but our water supplies are decreasing. Desalination offers an unconventional source of fresh water to meet the needs of the world’s growing population. However, the process harms marine organisms and their natural environments, and exacerbates the threat of climate change. Examination of environmental ethics suggests that prioritizing concerns about environmental and community health is vital to the successful establishment and operation of desalination plants.
Introduction
Water is the most abundant compound on Earth, covering 71% of the planet’s surface, but globally we face increasing challenges of water scarcity. Sixty-nine percent of fresh water is inaccessible because it is in the form of glaciers and permanent snow cover. Of the water we can access, less than 1% is considered potable [1]. As rapid human population growth continues and the impacts of climate change intensify, the few freshwater sources we have are becoming unreliable and more difficult to access. But we do have plenty of saltwater.
Enter desalination, the “process of removing salts from water to produce water that meets the quality (salinity) requirements of different human uses” [2]. Desalination allows us to obtain fresh water for domestic and municipal purposes from the vast amount of saltwater present on Earth. While the technology helps provide an essential water source for people in water-scarce areas, it harms marine life and degrades air quality. When the product water leaves the desalination plants, its distribution may not be equitable. These factors pose ethical dilemmas related to the environment, justice, and fairness. As the expansion of desalination technology continues around the world, we must prioritize the health of the natural environment and the communities that this technology impacts.
From Seawater to Fresh Water
Since the 1950s, desalination technology has enabled humans to separate salt from seawater and brackish water to generate fresh water. This is especially helpful in the Middle East and North Africa (MENA), the most water-scarce region in the world [3]. With little rainfall and high evaporation rates, countries such as Saudi Arabia, the United Arab Emirates, Kuwait, Malta, and Cypress have little access to conventional water sources [2, 3]. Desalination technology helps the MENA region bridge the gap between its supply of just 1% of the world’s fresh water and the high demand of its population.
The two main types of desalination technology used globally are membrane and thermal desalination. Membrane desalination, which uses reverse osmosis, relies on a semi-permeable membrane that blocks salt but allows water to pass through, while thermal desalination makes use of thermal energy to evaporate the water into water vapor and later condense it into the product water. With either method, the overall process is essentially the same: desalination plants take in saline water from a water source; separate salt, minerals, and particles from the water; dispose of the unwanted materials; and move the product water to post-treatment so it can be distributed [1].
In pretreatment, suspended matter and biomatter are removed from the feedwater and its pH is adjusted to prevent fouling, or the accumulation of unwanted material on solid surfaces in the plant. Coagulant chemicals such as ferric salts, aluminum salts, and polyelectrolytes are added to help achieve this, and biocides are included to prevent biofouling specifically. Furthermore, corrosion inhibitors prevent metallic parts from corroding and contaminating the water. Following pretreatment, the separation of salt and water generates the product water and brine, the waste product of desalination. In seawater desalination, the brine disposal method is typically to discharge back into the bodies of water from which the feedwater was sourced [1].
Impact on Marine Life and Environmental Ethics of Desalination
The intake of large volumes of seawater, discharge of brine, and release of emissions from desalination plants are major areas of environmental concern. Water intake may change the sediment transport pattern, increase soil salinity, and result in seawater intrusion into ground water. Also, the force of the operation removes organisms from their natural habitats, and tiny organisms like phytoplankton, fish eggs, and larvae may pass through the finest screen size of intake systems and die, while slightly bigger animals become trapped between intake screens with no way to escape [4]. Even large animals can be injured or killed when the high flow velocity of feedwater pins them to external intake screens [1, 4].
These organisms experience further damage higher mortality when desalination plants release brine as a waste product. Because desalination plants typically dispose of brine in the ocean, it influences marine environment health through its salinity, temperature, and residual chemicals. Brine from desalination plants has 1.5 to 2 times the salinity of seawater and contains chemicals that were added during desalination. These high levels of salinity, along with the chemical additives such as antiscalants and coagulants, and toxic compounds formed from disinfection byproducts, cause marine organisms with low tolerance for such environmental contamination to die. If their tolerance is high enough to escape death, organisms still face possible changes in their metabolic and growth rates and must contend with other effects of brine on their environment, such as the decrease in light penetration depth caused by heavy metals and the increase in sediment salinity and reduction of oxygen solubility brought about by increased seawater salinity. Altogether, these effects reshape benthic communities and may even introduce non-indigenous species to the area [1].
Both membrane and thermal desalination methods result in the effects described above, but thermal desalination has a unique impact due to the temperature of its discharge, which is 5-15 ºC higher than ambient seawater temperature. This increases the overall seawater temperature in the area, which can cause thermal shock, increasing organisms’ mortality rate. Combined with the increase in salinity, the higher water temperature also contributes to the reduction of its concentration of dissolved oxygen, putting marine organisms under greater stress [1].
Brine may even be a larger problem for marine environments and organisms than initially thought. According to previous assessments, the amount of brine discharge was about the same as the amount of product water (i.e., 50% fresh water and 50% brine) [2]. However, a 2018 analysis from researchers at the United Nations University: Institute for Water, Environment and Health, Canada estimates that global brine production is actually 50% greater than those estimates. This means that for every liter of fresh water produced, 1.5 liters of brine are discharged [2].
Desalination plants also damage marine environments and organisms through their emissions. The processes undertaken by plants are energy-intensive. Seawater membrane desalination consumes 2-7 kWh of electrical energy per 1 m3 of product water, and thermal plants consume a combination of electrical and thermal energy, anywhere from 1.5 kWh electrical and 6 kWh thermal to 3.5 kWh electrical and 12 kWh thermal per 1 m3 of product water, depending on the temperature being used [1]. Fossil fuels are still the primary source used to create this energy, which means that coal, oil, and natural gas power the majority of desalination plants around the world. The use of fossil fuels to meet these high energy demands makes desalination plants significant emitters of greenhouse gases, such as CO2, NOx, and SOx, as well as particulate matter [1]. Greenhouse gases hurt the Earth in a variety of ways, but the harm to marine life specifically comes when these emissions make their way into ocean water.
Anthropogenic CO2 emissions, such as those from burning fossil fuels, are changing the chemistry of seawater in a process called ocean acidification. This process has been intensifying as oceans absorb increasing quantities of CO2, and around the world, marine animals that cannot adjust to the rapidly changing conditions are dying. For example, shellfish such as mussels, oysters, and abalone are having trouble building their shells and reproducing, and other fish are finding it more difficult to detect predators or locate suitable habitats. The destruction of these species puts many food webs at risk, impacting organisms of all shapes and sizes [5]. Significant environmental impacts like these raise concerns about the establishment and operation of desalination plants and push us to examine our relationship with the environment.
Desalination’s threat to marine life exhibits a relationship in which we as humans mainly take from nature. We often leave some kind of waste or damage in our wake and do little to nothing to help nature recover. This behavior demonstrates that we typically think of our relationship with nature in an anthropocentric manner, the idea that nature exists for the sake of human use [6]. This long-held outlook has led to our extreme exploitation of the environment. For example, a total of 17% of the Amazon rainforest is gone, and in just one year, human activity destroyed 3,769 square miles of it. That’s larger than Yosemite National Park, twelve times the size of New York City, and a 30% increase compared to the previous twelve-month period [7, 8]. Another example is overfishing, which has led to the collapse of fish populations. According to the UN Food and Agriculture Organization, one third of commercial fish stocks are overfished and over half are being fished at their fullest yields [9]. Because of the resulting destruction of the natural environment, the view that we must preserve nature for the survival of future human generations has gained enormous prevalence. We need to sustain the health of all ecosystems to ensure that humans can live on a habitable Earth. This argument posits that all non-human organisms and objects in nature have value relative only to their usefulness to humans [6].
In contrast, the framework of environmental ethics emphasizes that the value of the natural environment is not just instrumental; it is intrinsic [6]. It does not exist solely to serve human needs, as organisms and other components of the environment have value on their own. This is different from most western ethical frameworks, which are anthropocentric (actions and the consequences of those actions are in relation to human concerns and well-being).
The natural environment and non-human organisms may not think and operate in the same way that humans do, but that does not mean they do not have value for their own sakes. Eric Katz, the founding Vice President of the International Society for Environmental Ethics, argues that natural entities have their own purpose and interests independent from those of humans, regardless of their complexity. Therefore, they deserve moral respect and should not be treated as means to an end [6]. John Muir, “Father of our National Parks,” and forester Aldo Leopold advocated for the conservation of wild organisms and their natural habitats in pursuit of the aesthetic preservation of nature and “as a rejection of the crudely economic approaches to the value of natural objects”—in other words, though natural resources like water may have an economic value to humans, we should prioritize appreciation and respect for nature [6]. Muir was instrumental in convincing the U.S. government to establish national parks, areas designated for the conservation of wildlife, such as Yosemite and Yellowstone, which survive and thrive to this day [10]. Our protection of these natural spaces and areas throughout the world does not mean we can neglect the health of the areas outside the boundaries that humans establish, though; all nature has its own value. We need to make the health of the environment and wildlife a genuine priority while we utilize nature’s resources.
If the natural environment and non-human organisms have purposes which do not concern humans, then the way desalination plants injure, kill, and remove from their natural habitats marine organisms of all shapes and sizes is a continued infringement upon the autonomy of marine life.
Air Pollution and Environmental Justice
The emissions of desalination plants do not only affect inhabitants of the oceans; at higher altitudes, the air pollution caused by those emissions also endangers human health. A dilemma associated with desalination plants is that their emissions contribute to climate change, but they exist because climate change has “increased droughts around the world” and therefore made freshwater sources scarce and unreliable [11]. In other words, the desalination reaction meant to support human health and address water scarcity due to global warming requires an increased release of greenhouse gases, thereby exacerbating the problem desalination is attempting to help solve. People who are exposed to air pollution due in part to desalination plants can experience reduced lung function, respiratory infections, and aggravated asthma, and furthermore, air pollution is linked to 4.2 million premature deaths caused by heart disease, stroke, chronic obstructive pulmonary disease, lung cancer, and acute respiratory infections [12]. Failure to mitigate the impacts desalination has on the environment puts present and future generations at grave risk. With the detailed knowledge we have about the causes and dangers of climate change, it is wrong not to act to reduce desalination’s damage to the environment.
The threat of climate change demonstrates the importance of caring for the health of both humans and the environment. Environmental ethics encourages us to decenter human concerns to respect the value of nature, but we must also consider the impact that environmental harm has on people, especially those who belong to marginalized groups. The concept of environmental justice embodies this concern, pointing out a vital aspect of our connection to the environment: our health depends on the environment’s health. Environmental justice is anthropocentric, but it is not self-serving; it is based on community, with a focus on civil rights and public health. It works to protect human communities from the impacts of pollution, and more specifically “challenge[s] the unfair distribution of toxic, hazardous and dangerous waste facilities, which [are] disproportionately located in low income communities of color” [13]. A growing number of studies support the fact that this unfair distribution is prevalent; for example, a 2018 study from the U.S. Environmental Protection Agency’s National Center for Environmental Assessment found that at national, state, and county levels, people of color in low-income communities are exposed to more particulate matter than white people and those who are more affluent. Other studies have similarly found that people of color are more likely to live near sources of pollution like toxic waste facilities, landfills, and oil wells [14].
In Los Angeles County, high levels of lead contamination from the closed Exide Technologies battery recycling plant continue to harm residents who are mostly working-class Latinos, and throughout California, Black, Latino, and low-income residents are most likely to live near unplugged oil and gas wells that release toxic emissions and flammable gases [15, 16]. With their disproportionate exposure to pollution, the people who live in these communities have far less access to resources like clean air and water and healthy soil than those in wealthy suburbs [17]. This is environmental injustice. As we look to desalination as an attractive option to meet our fresh water needs, we must consider how other industrial systems impact people to ensure it does not intensify these inequities.
Though desalination plants exist mainly to support people’s water needs, they should also minimize any dangers to other aspects of human health and benefit the communities where they are located. A desalination plant proposed by California American Water (Cal-Am), for instance, would have threatened environmental justice in Marina, CA. Marina is located in Monterey Bay, a region that is isolated from state and federal aqueducts, which leaves communities with limited water options. Most residents rely on Cal-Am to supply some of the most expensive water in the U.S. from the Carmel River, so a desalination plant could help reduce that cost [19]. However, before the California Coastal Commission could vote on approval of the plant in September 2020, Cal-Am withdrew its proposal (at least for the time being) after pushback from the community over environmental justice concerns [18].
In this case, a desalination plant would worsen the conditions of the community instead of helping it. In Marina, one-third of the community is low-income and many of the residents speak little English. The proposed location was a sand mine, where industrial use has already impacted the area for an entire century, removing shorebirds and rare butterflies from their habitats. Besides the mine, a regional landfill, regional composting facility, regional sewage plant, and municipal airport already disproportionately affect the community with industrial use [20]. Replacing the sand mine with a desalination plant would escalate these impacts on the wildlife and human residents and continue to block the community from accessing its coastal resources. Furthermore, none of the product water would even be distributed to residents of Marina; instead, it would be transported to other cities, businesses, and farms [19]. These other cities, like nearby Castroville, are also in great need of water, but Marina would get nothing for bearing the brunt of the negative environmental impact. It is unfair that those who would benefit from the desalination plant, including those profiting from Cal-Am’s ventures, are not the same people who would pay the price of exposure to pollution and the health problems that follow. This proposed plant, like many other cases of environmental injustice, would marginalize the community and treat Marina residents as though they are of lesser value than residents of other communities.
In lieu of the Marina desalination plant, a new recycled water project called Pure Water Monterey could fulfill Monterey Bay’s water needs. In a report, Coastal Commission staff urged the board to deny the desalination plant and suggested that an expansion of Pure Water Monterey, which would provide nearly 2.8 million cubic meters of water per year to the existing Pure Water facility, would be a better investment for Cal-Am [19]. The report states that the project would overall be cheaper, more equitable, and less environmentally damaging than the desalination plant proposal [20]. Specifically, water from the desalination plant was predicted to have cost two to three times as much as the recycled water. Low-income ratepayers in nearby cities like Seaside should not be forced to pay even higher rates when they already pay some of the highest in the country, and again, Marina should not be burdened with the pollution and coastal impact, especially when a desalination plant will only harm residents. When communities are in need, it is important to recognize that desalination is not always the best answer. If another option that has less environmental impact and promotes equity is available, that is the solution we should always strive toward.
Conclusion
Despite desalination’s impact on the environment, the fact remains that this technology is vital in some areas of the world. The climate of countries like Saudi Arabia, Malta, and Kuwait restricts their residents’ access to sufficient renewable fresh water sources, so they greatly benefit from desalination as a reliable source. In other places, however, the benefit of desalination may not outweigh the environmental and social cost. Marina’s low-income community would gain nothing from a desalination plant except increased exposure to pollution, and the possible recycled water system in Monterey Bay would pose a much less risky way to meet the community’s water needs. To protect the health of the natural environment and of the community, we should employ desalination only in places that have no viable alternative.
As we continue to utilize desalination, technology will likely improve, reducing the environmental harm it currently causes. Already, engineers are working to find uses for discharged brine and attempting to develop renewable energy methods to meet the energy demands of desalination plants [21]. Until those mitigation methods come to fruition, though, we will need to do our utmost to limit the amount of brine and greenhouse gas emissions released by today’s desalination technology. Ultimately, to work toward a better world, we need to start by valuing the natural environment—independent of its usefulness to humans—and the health of marginalized people who are especially vulnerable to environmental damage and climate change, for such a world cannot truly be better if we neglect our planet or our people along the way.
By Audrey Kono, Annenberg School for Communication and Journalism, University of Southern California
About the Author
At the time of writing this paper, Audrey Kono was a junior at USC majoring in Communication and minoring in Environmental Studies. She first gained her love for the environment while growing up in Monterey Bay, CA.
References
[1] K. Elsaid, M. Kamil, E. T. Sayed, M. A. Abdelkareem, T. Wilberforce, and A. Olabi, “Environmental impact of desalination technologies: A review,” Science of The Total Environment, vol. 748, pp. 1-19, 2020.
[2] E. Jones, M. Qadir, M. T. V. Vliet, V. Smakhtin, and S.-M. Kang, “The state of desalination and brine production: A global outlook,” Science of The Total Environment, vol. 657, pp. 1343-1356, 2019.
[3] K. Scott, “Can the Middle East solve its water problem?,” 22 Mar. 2019. [Online]. Available: https://www.cnn.com/2018/07/11/middleeast/middle-east-water/index.html. [Accessed: 28 Oct. 2020].
[4] J. Robbins, “As water scarcity increases, desalination plants are on the rise,” Yale Environment 360, 11 Jul. 2019. [Online]. Available: https://e360.yale.edu/features/as-water-scarcity-increases-desalination-plants-are-on-the-rise. [Accessed: 23 Oct. 2020].
[5] “Ocean acidification,” National Oceanic and Atmospheric Administration, Apr. 2020. [Online]. Available: https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-acidification. [Accessed: 26 Oct. 2020].
[6] A. Brennan and Y.-S. Lo, “Environmental ethics,” Stanford Encyclopedia of Philosophy, 21 Jul. 2015. [Online]. Available: https://plato.stanford.edu/entries/ethics-environmental/. [Accessed: 14 Oct. 2020].
[7] U. Irfan, “Brazil’s Amazon rainforest destruction is at its highest rate in more than a decade,” Vox, 18 Nov. 2019. [Online]. Available: https://www.vox.com/science-and-health/2019/11/18/20970604/amazon-rainforest-2019-brazil-burning-deforestation-bolsonaro. [Accessed: 25 Oct. 2020].
[8] C. Dwyer, “Amazon rainforest sees biggest spike in deforestation in over a decade,” NPR, 18 Nov. 2019. [Online]. Available: https://www.npr.org/2019/11/18/780408594/amazon-rainforest-sees-biggest-spike-in-deforestation-in-over-a-decade. [Accessed: 25 Oct. 2020].
[9] FAO, “The state of world fisheries and aquaculture 2018 – Meeting the sustainable development goals.” FAO, Rome, Italy, 2018.
[10] “National Park Service founders: John Muir,” National Parks Service. [Online]. Available: https://www.nps.gov/bestideapeople/muir.html. [Accessed: 26 Oct. 2020].
[11] “The impacts of relying on desalination for water,” Scientific American, 20 Jan. 2009. [Online]. Available: https://www.scientificamerican.com/article/the-impacts-of-relying-on-desalination/. [Accessed: 13 Oct. 2020].
[12] “Ambient air pollution: Health impacts,” World Health Organization, 25 Sep. 2018. [Online]. Available: https://www.who.int/airpollution/ambient/health-impacts/en/. [Accessed: 26 Oct. 2020].
[13] K. D. Warner and D. DeCosse, “A short course in environmental ethics: Lesson five,” Markkula Center for Applied Ethics, 1 May. 2009. [Online]. Available: https://www.scu.edu/environmental-ethics/short-course-in-environmental-ethics/lesson-five/. [Accessed: 14 Oct. 2020].
[14] N. Colarossi, “10 egregious examples of environmental racism in the US,” Insider, 13 Aug. 2020. [Online]. Available: https://www.insider.com/environmental-racism-examples-united-states-2020-8. [Accessed: 27 Oct. 2020].
[15] T. Barboza and B. Poston, “The Exide plant in Vernon closed 3 years ago. The vast majority of lead-contaminated properties remain uncleaned,” Los Angeles Times, 26 Apr. 2018. [Online]. Available: https://www.latimes.com/local/lanow/la-me-exide-cleanup-20180426-story.html. [Accessed: 26 Oct. 2020].
[16] M. Olalde and R. Menezes, “The toxic legacy of old oil wells: California’s multibillion-dollar problem,” Los Angeles Times, 6 Feb. 2020. [Online]. Available: https://www.latimes.com/projects/california-oil-well-drilling-idle-cleanup/. [Accessed: 26 Oct. 2020].
[17] K. D. Warner and D. DeCosse, “A short course in environmental ethics: Lesson three,” Markkula Center for Applied Ethics, 1 May. 2009. [Online]. Available: https://www.scu.edu/environmental-ethics/short-course-in-environmental-ethics/lesson-three/. [Accessed: 25 Oct. 2020].
[18] R. Xia, “Water company withdraws desalination proposal as battle over environmental justice heats up,” Los Angeles Times, 17 Sep. 2020. [Online]. Available: https://www.latimes.com/california/story/2020-09-16/monterey-bay-desalination-plant-withdrawn. [Accessed: 12 Oct. 2020].
[19] R. Xia, “Is California serious about environmental justice? This water fight is a test,” Los Angeles Times, 15 Sep. 2020. [Online]. Available: https://www.latimes.com/california/story/2020-09-15/cal-am-desalination-coastal-commission-marina-california. [Accessed: 12 Oct. 2020].
[20] California Coastal Commission Staff, “Staff report: De Novo appeal and Consolidated Coastal Development Permit.” San Francisco, CA, 25 Aug. 2020.
[21] H. Fountain, “The world can make more water from the sea, but at what cost?,” New York Times, 22 Oct. 2019. [Online]. Available: https://www.nytimes.com/2019/10/22/climate/desalination-water-climate-change.html. [Accessed: 9 Nov. 2020].
Links for Further Reading
Read the report from the California Coastal Commission staff: https://documents.coastal.ca.gov/reports/2020/9/Th3a&4a/Th3a&4a%20Staff%20Report.pdf
Desalination mitigation methods: https://doi.org/10.1016/j.scitotenv.2020.140125
How overfishing impacts food webs, with links to other information about wild seafood and environmental impact: https://www.seafoodwatch.org/ocean-issues/wild-seafood/overfishing
Poseidon Water’s proposal for a desalination plant in Huntington Beach: https://www.latimes.com/environment/story/2020-08-06/poseidons-huntington-beach-desalination-plant-still-in-choppy-waters
California Coastal Commission’s power to review environmental justice: https://coastal.ca.gov/env-justice/