Seventy percent of the planet is covered in water, out of that 332 million cubic miles of water on this planet only 2.5 of water is considered fresh. Out of that 2.5 percent of freshwater on Earth the Surface water most often used by humanity and animals consists of systems of rivers, lakes, and mountain runoff. These water system reliant on earth’s recycling through the biosphere is only a measly 1.2 percent of the freshwater available. Even if we consider the Groundwater resources that more developed nations use for water resources, humanity still has a problem. According to data taken in 2015 by the World Health Organization and Unicef 11% of the world’s population does not have access to basic drinking water sources. With an expected dramatic increase in population, overall wealth of the average person, increase in meat production, and climate effects of global warming, human water usage is predicted to increase in developing populations by 50% and in the developed countries by 18% between 2007 and 2025. This could possibly lead to a doubling in the percent of the world’s population without potable water.
Where does humanity go to collect more water? In places like the American West and the Middle East, the impact of Droughts, large populations, increase agricultural output, and industry have greatly depleted precious but fickle natural freshwater resources. These water resources like the Jordan River in the Middle East or the Colorado river basin have depleted dramatically with the overuse of a once sustainable and ever replenishing system. Groundwater has been used to subsidize the lack of surface water in many places but the overuse of these resources has lead to dramatic drops in water tables. In many places like the Midwest these water resources are in aquifers a few miles below the surface under layers of material impeding water replenishment, making them unviable as sustainable water resource for high demand systems. Other than making our system more efficient, where else can we find more water?
The answer is in plain sight. The ocean, containing 97% of water on earth is almost an unending source of water. The problem it is not usable in its salty state.
3. Locations and Plants
There are thousands of desalination plants located around the world. One of the most recently built plants is located in Carlsbad California, where it provides 50 million gallons per day of desalinated water from the Pacific Ocean. This 1-billion-dollar plant provides around 10% of the water needed in San Diego County. Desalination was chosen as an alternative water source for the area, because they receive 90% of their water from northern California and the Colorado River. And before the opening of the plant, “water for homes and businesses is imported from sources that are increasingly stressed” (California). With populations growing throughout California, San Diego County has opted to try to reduce their dependence on outside sources to get their water. Other areas such as Huntington beach and Santa Barbara are exploring options to open or reopen (in the case of Santa Barbara) desalination plants to meet increasing water demands (California). As global warming worsens, we will likely see more water stressed areas in southern California turn to desalination.
The largest reverse osmosis plant is in Israel, Sorek, which produces 624,000 cmd or 165 mgd. Israel has greatly reduced its dependence on outside sources for their water, “in 2004 the country relied entirely on groundwater and rain, it now has four seawater desalination plants running … Those plants account for 40 percent of Israel’s water supply” (Cheap). Additionally, Sorek produces “the cheapest water from seawater desalination produced in the world” (Cheap). This cost decrease is a result of engineering improvements. Mainly the fact that they were able to reduce the amount of energy consumed per cubic meter to 3.5 kwh (Frangoul). With the costs associated with desalination continuing to decrease, desalination continues to become more attractive as a source of water. Israel continues to serve as an example for the benefits of reverse osmosis and desalination.
In the early 2000’s Australia experienced a serious depletion of water levels in their reservoirs resulting from multiple years with significantly less rainfall. In an effort to reduce their dependence on the weather, “Australia’s five largest cities are spending $13.2 billion on desalination plants” (Onishi). Australia built these plants between 2007 and 2012, and to the public’s distaste, many of these tax funded plants were never used. Rainfall returned and the additional water from desalination was not needed to fill their reservoirs, that was until the 2016 when the government ordered 50 gigalitres of desalinated water and stated an additional minimum order of 15 gigalitres of water for the next three years from the Victoria desalination plant (Hobday). These orders came after reservoir levels in their reservoirs had not been full for 20 years and is meant to “help avoid the social and economic costs of water restrictions on households, businesses and farmers” (Neville). Although the public was not happy with these plants not being used, Australia took huge steps towards drought proofing themselves, with their plants able to provide around 30% of needed water (Onishi). Because of this, they will not have water restrictions placed on themselves for a long time because of their desalination plants.
4. Cost
One of the most critical aspects of water desalination is cost. Although desalination remains more expensive than alternative methods the unit costs for desalination processes have fallen considerably over the last three decades. This downward trend is generally associated with technology improvements and advances in the ability to recover more energy from the desalination process.
Desalination technology has been around for years and the process becomes more sophisticated each day, however desalination still remains relatively expensive. A thousand gallons of freshwater from a desalination plant costs the average US consumer $2.50- $5.00 compared to $2.00 for conventional freshwater (Bienkowski).
The large range of cost for desalination comes from the uncertainty in plant costs. In order for a desalination facility to function there are a variety of factors that influence the cost of a plant. First and foremost, there has to be some method of getting seawater from the ocean into the facility. As an example of varying costs, an open intake system will cost roughly half as much as a complex tunnel for an offshore intake system. A beach intake is traditionally less expensive for equipment, but when you factor in land acquisition, a beach intake is typically 50% more costly than an open intake system. The construction of the intake system can reach up to 1/3 of the total project cost (Rogers). For this reason, it makes much for sense to build desalination facilities in close proximity to the ocean to avoid costly intake systems.
The desalination process also uses a tremendous amount of energy. Desalination plants around the world consume more than 200 million kilowatt-hours each day. Energy costs are estimated to be 55 percent of the plants total operational costs. On average it takes a desalination facility between three to ten kilowatt-hours of energy to produce one cubic meter of freshwater, while a traditional drinking water treatment plant uses well under one kilowatt-hour per cubic meter (Rogers).
Although the costs of a desalination facility are more expensive than traditional methods, there has been a downward trend in overall costs, and technological advances will only continue to drive the costs down. It is also important to consider that although more expensive, desalination gives us access to an endless supply of water. The drought-proof nature of the desalination process should make it the premier choice for water treatment.
5. Environmental Impact
6. Benefits, Drawbacks and Potential Solutions
The most apparent benefit of water desalination is that it can be used to provide accessible drinking water to areas that are in drought or where no natural drinking water supply exists. For communities without easy water access, this process is invaluable. However, as mentioned, this technology comes at a high cost in terms of building and operation (Ackerman). While the desalination process is more expensive than regular surface water treatment, the need for this process is growing. According to Christopher Gasson of Global Water Intelligence,
“At the moment, around 1% of the world’s population are dependent on desalinated water to meet their daily needs, but by 2025, the UN expects 14% of the world’s population to be encountering water scarcity. Unless people get radically better at water conservation, the desalination industry has a very strong future indeed. Seawater desalination is the only additional renewable source of freshwater available on this planet.” (Global Water Intelligence).
It seems to be inevitable that water desalination will become a major industry in the coming years. The question now is: how can it be made as efficient as possible, in terms of cost and energy use? One possible solution is to try and alter the process that is used to pull salt from the water. The current leading technology is reverse osmosis- salt water pumped through membrane to filter the water and make it potable. However, there is ongoing research on methods that could reduce energy consumption, and with it, cost. One proposed method is to alter the membrane used in the reverse osmosis process. One research group has found that nanoporous graphene- a type of carbon- created a membrane that was hundreds of times more permeable to water than the polymer membrane currently used. This level of permeability could result in a 15-50% reduction in energy consumption (Zimmerman). That drastic of an energy reduction would make the process much more affordable.
A combination of this reduction in energy and having energy provided from renewable resources such as solar and wind could maximize the affordability of desalination.
Works Cited
- Ackerman, Anne. “Advantages & Disadvantages of Desalination Plants.” Sciencing, Sciencing, 25 Apr. 2017.
- Bienkowski, Brian. “Desalination is an expensive energy hog, but improvements are on the way.” Public Radio International, www.pri.org/stories/2015-05-15/desalination- expensive- energy-hog-improvements-are-way. Accessed 05 Nov. 17.
- “Desalination Industry Enjoys Growth Spurt as Scarcity Starts to Bite.” Global Water Intelligence, GWI,
- Frangoul, Anmar. “Turning the sea into drinking water.” CNBC, CNBC, 9 June 2016, www.cnbc.com/2016/06/09/turning-the-sea-into-drinking-water.html.
- Hobday, Liz. “Victoria’s Desalination Plant Finally Delivers as Government Places Order for More Water.” ABC News, ABC News, 19 Mar. 2017, www.abc.net.au/news/2017-03-19/victoria-desalination-plant-finally-delivers-water/8367554.
- Neville, Lisa. “Desalination Water Order Placed .” Desalination Water Oder Placed For 2017-18, Premier of Victoria, 15 May 2017, www.premier.vic.gov.au/desalination-water-order-placed-for-2017-18/.
- Onishi, Norimitsu. “Arid Austraiia Sips Seawater, but at a Cost.” The New York Times. The New York Times, 10 July 2020, www.nytimes.com/2010/07/11/world/asia/11water.html.
- Rogers, Paul. “Nation’s largest ocean desalination plant goes up near San Diego; Future of the California coast?” The Mercury News, The Mercury News, 23 Jan. 2017, www.mercurynews.com/2014/05/29/nations-largest-ocean-desalination-plant-goes-up-near-san-diego-future-of-the-california-coast. Accessed 05 Nov. 17
- Talbot, David. “California Turns to the Pacific Ocean for Water.” MIT Technology Review, MIT Technology Review, 28 Mar. 2016, www.technologyreview.com/s/633446/desalination-out-of-despiration/.
- Talbot, David. “Cheap Water from the Worlds Largest Modern Seawater Desalination Plant.” MIT Technology Review, MIT Technology Review, 8 July 2015, www.technologyreview.com/s/534996/megascale-desalination/.
- Zimmerman, Leda. “Cheaper, Energy Efficient Ways to Desalinate Water.” MIT Spectrum, MIT, 2015.