Water desalination is the process of removing mineral components from saline water. One of its applications centered on removing salt and other minerals from seawater to make it suitable for human consumption and irrigation. However, despite these apparent benefits, saltwater desalination has critical drawbacks that make it costly and inefficient.
The Pros: Advantages of Desalination
1. Addresses Issue About Water Scarcity
About 1 percent of the global human population is dependent on desalinated water. However, a 2014 report published by MIT Review noted that an estimated 1.8 billion people would suffer from water scarcity by 2025. The United Nations expects 14 percent of the human population to become dependent on desalinated water.
Take note that there are established sources of potable water. These are lakes and rivers, groundwater or aquifers, and water recycling, among others. However, these sources are either susceptible to depletion, unavailable in some regions of the world, or both.
Nevertheless, a key advantage of water desalination is that it provides communities with an alternative source of potable water. Countries in the Middle East, as well as Australia, have depended on seawater desalination to meet the water requirements of their population. Undeniably, desalination facilities are critical infrastructures in dry and arid countries.
2. Supports Agriculture and Food Production
It is also worth noting that seawater is not only undrinkable but also unsuitable for irrigation due to the high concentration of salt that would render a land unable to support plant life. Note that it is also impossible to feed livestock with saline water.
Hence, as the human population increases, water consumption also increases not only for drinking but also for supporting agricultural activities and food production. Desalination provides a solution for addressing both water and food requirements of a growing population.
A study by D. Zarzo, E. Campos, and P. Terrero explored the experience of Spain in water desalination for agriculture. They noted that the country provides a prime example of success in using desalinated water for agricultural purposes. Currently, Spain has large capacity plants and farmer-owned facilities for producing irrigation water from saline water sources.
3. Enables Cogeneration Applications
Another benefit of water desalination is that it allows for the application of cogeneration. As a backgrounder, cogeneration involves the use of a heat engine or power station to generate electricity and utilize excess heat for other purposes.
Countries rich in fossil fuel resources benefit from water desalination through cogeneration. They burn fossil fuels not only for electricity generation but also for producing desalinated water, thus maximizing the utility and capacity of their power plants.
The International Atomic Energy Agency also noted that water desalination using nuclear energy or utilizing dual-purpose nuclear power plants has benefited countries such as Japan, India, and Kazakhstan. Again, cogeneration maximizes the utility not only of power plants but also of energy resources or inputs.
The Cons: Disadvantages of Desalination
1. Economic Costs and High Energy Requirements
One of the main disadvantages of water desalination centers on economic costs. The process is energy intensive. With the addition of costs from infrastructure construction, operation, and maintenance, producing desalinated water is generally more expensive than tapping water sources from lakes and rivers, groundwater, or through water recycling and water conservation.
Desalination is inherently expensive for countries with no abundant supply of natural energy resources. They need to import these resources or build more capacities for alternative energy production. The costs would make desalinated water expensive for end-use consumption.
Although advances in technology have driven down the cost of water desalination, a study by Y. Zhou and R. S. J. Tol argued that it would still be costly for developing countries, those that are placed on the interior of a landmass, or those situated at high evaluation. Interestingly, these countries usually have substantial water problems.
Zhou and Tol further explained that aside from the costs associated with constructing and maintaining a plant, including the cost involved in energy input, transporting the desalinated water inland or in elevated regions provide additional costs that can equal the costs of water desalination.
2. Negative Impacts on the Environment
Another drawback of desalination is its various negative impacts on the environment. Take note that aside from having high energy requirements, which translates to carbon emission in the case facilities powered by hydrocarbons, the construction, operation, and maintenance of these facilities produce a number of negative environmental externalities.
The following are the specific adverse environmental impacts of desalination:
• Affects Marine Species: The U.S. Environmental Protection Agency explained that the intake of water from seas could suck fish and shellfish, as well as their eggs. Once sucked, these marine species may be killed due to physical stress, exposure to chemical, or heat. Some larger organisms are instantly killed when trapped at the front of intake structures.
• Produces Brine: A byproduct of desalination is wastewater with a high-concentration solution of salt called brine. It is naturally occurring. However, when produced due to industrial activities, it poses an environmental risk because of its corrosive effects and the toxicity of other chemicals diluted in it. Nonetheless, there are different ways to properly dispose of brine such as through dilution or wastewater treatment.
• Other Impacts: Facilities need to be built on about 25 acres of land on or near a shoreline. Hence, there is an issue of land use. Building them far from a water source or on inland also produces environmental risks due to energy inefficiency and possibilities of leaks from the piping system that could contaminate freshwater sources such as aquifers.
FURTHER READINGS AND REFERENCES
- Environmental Protection Agency. 2017. “Cooling Water Intakes.” Environmental Protection Agency. Available online
- International Atomic Energy Agency. 2019. “Nuclear Desalination. International Atomic Energy Agency. Available online
- Talbot, D. 2014. “Desalination Out of Desperation.” MIT Technology Review. Available online
- Zarzo, D., Campos, E., and Terrero, P. 2012. “Spanish Experience in Desalination for Agriculture.” Desalination and Water Treatment. 51: 53-66. DOI: 10.1080/19443994.2012.708155
- Zhou, Y. and Tol, R. S. J. 2005. “Evaluating the Costs of Desalination and Water Transport.” Water Resources and Research. 41(3). DOI: 10.1029/2004WR003749