Abstract
Desalinization was researched for its feasibility as a long-term solution to current and future water demands worldwide. After briefly describing the two primary desalinization processes, thermal processes and reverse osmosis, several environmental and financial issues were evaluated for their impact on the feasibility of desalinization. Specifically, chemical waste disposal, brine effluent disposal, energy consumption, carbon emissions, and total financial cost of desalinization were discussed. Several examples of current technological improvements to desalinization were reviewed for their contributions to addressing the concerns of current desalinization technology, along with any known drawbacks to employing the new technology. Finally, current use trends and future predictions are made regarding the continued use of desalinization as a viable solution to water scarcity, especially in coastal regions where seawater is easy to obtain. A conclusion is drawn that, given the trends to address the waste byproducts of desalinization, it is a feasible solution to global water demands, given the improvements are implemented in a responsible manner.
Introduction
“Worldwide, some 700 million people don’t have access to enough clean water. In 10 years the number is expected to explode to 1.8 billion. In many places, squeezing fresh water from the ocean might be the only viable way to increase the supply.”
Desalinization might be an option for solving this water crisis – but at what cost? This paper intends to show that desalinization has the potential to be the world’s answer to water scarcity. First, the two major techniques currently in use for desalinization around the world will be reviewed, along with their associated social, economic, and environmental costs. Then, emerging technologies in desalinization are presented, with their benefits and costs. Finally, an overview of the future projections of desalinization efforts is presented before conclusions are drawn regarding the future viability and need for desalinization as a primary source of water around the globe.
The Need – Water Scarcity
“Water scarcity is an abstract concept to many and a stark reality for others. It is the result of myriad environmental, political, economic, and social forces.”
While the exact figures vary from source to source on the total available freshwater on the planet, the figures all agree it is a small fraction of the total available water on Earth. 70% of the planet is covered with water, however, only 2.5-3% of it is freshwater, with the remaining 97.5% available as ocean or saltwater, too salty to be potable. Of the 2.5-3% of total water available as freshwater, most of it is inaccessible to humans. It is frozen in ice caps and glaciers, stored in the atmosphere or soil, too polluted to be useful, or too far beneath the surface to be extracted. That leaves humans with less than 1% of the total water on earth (some sources say as low as 0.007%) available as fresh drinking water ready for consumption with minimal effort.
Making matters more complicated, “geography, climate, engineering, regulation, and competition for resources” have made water availability a social justice issue as well, with “some regions seeming relatively flush with freshwater, while others face drought and debilitating pollution.” And, humans have not been efficient with water usage, either. By growing water-intensive crops in arid climates, or by creating water-intensive food products, the scarcity and social injustice is exacerbated. There is, without a doubt, a water scarcity issue for much of the developing world already, and with the world’s population continuing to grow, the scarcity will also grow without a sustainable (both in environmental and supply terms) source of clean water.
The topic at hand for this paper is whether desalinization is a feasible answer to this water scarcity. The hydrology cycle gives us drinking water primarily through the ground. Without other feasible alternatives to obtain water from the ground supply, and in order to shortcut the hydrology cycle to obtain a drinking water product directly from seawater, we must remove the salt from it. One potential answer to the problem of water scarcity is desalinization.
What is Desalinization?
Desalinization, briefly, is removing the salt from seawater to make a product with low enough salt content that it is safe for drinking. The full desalinization process to create a viable final drinking water product also includes various water treatment processes meeting other criteria, such as softness, safe microbial content through various means, disinfection, fluoride content, etc. However, those processes are not the primary topic of this paper, and will largely be ignored. This paper will focus primarily on the process of salt removal from the water itself, and its associated energy, chemical, and other material inputs and outputs.
Distillation
In its simplest form, desalinization was first accomplished through distillation, which is boiling water, capturing the steam, and condensing it back to water. However, distillation is energy-intensive, and not feasible for a large-scale operation. A more modern version of distillation, known as multi-stage “flash” evaporation (MSF) is in use today. In MSF, seawater is distilled through the use of heat to boil it while at the same time reducing the pressure by a applying a vacuum to the heating chambers. The water passes through a series of chambers (stages) that have progressively higher temperatures and lower pressures, vaporizing some amount of water as it moves through the process. The water vapor is removed from the chambers and then further treated to make it potable. The leftover salt brine from the process is typically pumped back into the sea.
The biggest drawback of MSF, not surprisingly, is “the energy required for MSF systems is ~90 kWh/kgal and is nearly all in the form of heat.” One of the only practical ways to deploy MSF is by co-locating an MSF plant with a power generation plant, drawing on the power plants’ heat production for the heat needed for the MSF process, while also providing any power needed to complete the process. MSF could also be deployed near an industrial facility generating a great amount of waste heat, such as foundries, glass operations, etc.
Another thermal desalinization process is called multiple-effect distillation. This process consists of multiple stages (or effects), wherein the feed water (seawater) is heated by steam in tubes, usually by spraying the seawater onto the hot tubes. When sprayed, some of the seawater evaporates immediately, and the steam flows into the next stage (effect), heating and evaporating more water. Since each stage reuses the energy from the previous stage, with progressively lower temperatures and pressures, the process is also more efficient than distillation.
Reverse Osmosis
A second, more recent method of desalinization is called reverse osmosis (RO). In order to explain reverse osmosis, it is best to describe osmosis. Osmosis is separating a solvent (seawater) from a solute (salt) by passing the liquid through a permeable membrane. The membrane is porous enough to allow the size of water molecules to pass through it, but will not allow the larger molecules of the salt through it. Because both the solvent and solute seek to balance their concentrations, an “osmotic pressure gradient” is generated in which only the solvent (fresh water) can pass through the membrane into the less pure solute as the concentrations try to equalize. So, in reverse osmosis, a pressure of at least the osmotic pressure of water (~350 psi) is applied to the seawater to reverse the normal flow across the membrane.
In the course of processing, commercial systems first filter the seawater to remove any solids. Then, the pH of the water is adjusted, and anti-scaling additives are used to prolong the life of the membranes. Then, the seawater is pressurized to pressures of 800-1000 psi to enact the reverse osmotic flow through the membrane. This pressure varies with the total dissolved solids (TDS), or salt concentration, of the water. The higher the TDS, the higher the pressure required to enact the RO process, thereby directly linking the salinity of the water with the energy input required. Large RO plants are in use today. In 2005, an RO plant with a capacity of ~29 million gallons per day was put into service in Singapore. Another plant in Israel, the Ashkelon plant has a peak capacity of ~86 millions gallons per day.
While RO has been a viable water treatment technology for over 50 years, there are more recent developments meant to make RO more efficient, mainly through the advancement of the membrane themselves. Membranes have been increasingly more productive by yielding more fresh water per membrane element. By increasing membrane density, each RO membrane has a higher surface area, without an increased diameter. There has also been work on fouling reduction inside the membranes, optimizing feedwater temperatures, and more.
The Challenges of Current Desalinization Efforts
Having looked at the two most basic technologies in desalinization, this section of the paper will illuminate the most common drawbacks of desalinization operations and the concerns they raise as the future of the world’s water supply.
Chemical Waste Disposal
As with all man-made processes, desalinization has byproducts that must be addressed. One of the current drawbacks to the process is the requirement of pre-treatment and cleaning, accomplished by adding caustic chemicals to the water before the desalinization process begins to make treatment more efficient and productive. The chemicals most prevalent in use are chlorine, hydrochloric acid, and hydrogen peroxide. All of these chemicals can be re-used, but not indefinitely. Over time, they lose their efficacy, and become a waste product requiring disposal. Some critics of desalinization and its waste products note the chemicals find their way into the plant discharge stream and into the ocean, where they harm plant and animal life. For desalinization to be viable, this waste stream must be addressed more fully.
Brine As a Waste Byproduct
Another one of the challenges of desalinization is the scale of the salt in seawater, compared to the levels of salt safe and desirable in drinking water. In this paper, the term “seawater” refers to water with an average salt concentration of approximately 34,000 parts per million (ppm) by weight of salt. Salt concentrations can vary widely around the world in different seas, with a range of 10,000 to 45,000 ppm. Meanwhile, fresh water will have a concentration of less than 500 ppm. With salt concentrations this high in seawater, the “problem” of salt in the water can quickly scale. For instance, at a concentration of 35,000 ppm, one million gallons of water (enough water for just 10,000 people for one day by First World usage standards), contains 291,900 pounds of salt. This large scale of salt as a byproduct is one of the largest hurdles to overcome in evaluating the sustainability or feasibility of desalinization.
The salt byproduct typically remains as a highly concentrated salty water product called “brine.” As such, there are currently eight primary methods for handling brine disposal. Most common for facilities near the ocean, the brine may be discharged back into ocean as effluent. This may be the case for inland facilities, too, if the facility is allowed to discharge the effluent as part of their National Pollutant Discharge Elimination System permits. However, most ocean species cannot tolerate the immediate rise in local salinity caused by the discharge of brine back into the area. This highly concentrated brine decreases oxygen levels, essentially suffocating the animals and plants in the area around desalinization plant discharge. Secondarily, the brine effluent could be discharged into rivers, lakes, or reservoirs. This would depend in large part on the tolerance of the ecosystem to handle the salt effluent in a brackish or even fresh water starting condition.
A third disposal options might be an evaporation pond, which is an impoundment area where the brine can accumulate for purposes of evaporating the water out of the brine, where the salt may be used for other purposes afterward. This type of disposal requires no federal permitting, but may required state monitoring. A fourth disposal technique is to use the brine as irrigation water, but this largely depends on the effluent salt concentration and the crop’s tolerance to it. This option is limited in its application.
A fifth typical disposal technique of brine is to inject it into porous rock. This option, called “deep well injection” requires drilling the rock, maintaining the well, permitting, and monitoring, all of which make it relatively expensive as a disposal option. Sixth, sewer discharge can be an option in locations where the water treatment facility can handle the concentration of the effluent. Seventh, brine can be used as a dust control agent on roadways or fields in dry or arid climates. Finally, the brine can be used as a de-icing agent on winter roads, particularly in higher concentrations. Of course, all of the brine disposal methods listed above must be evaluated for their feasibility and cost based on locality, permitting issues, brine concentrations, etc. Not all environmental or social conditions will tolerate or accept each of these disposal options, leaving the desalinization process with a large quantity of salt or brine to handle properly.
Power Consumption
A White Paper from the Desalinization Committee at WateReuse Association, a trade association dedicated to finding acceptance of recycled water in more applications, seeks to debunk what they consider to be a widely conceived misunderstanding of extreme energy use in the desalinization process. A table from their paper is shown below for various water treatment alternatives. Interestingly, the table shows (and the paper lays out more details to defend the data in the table) that large desalinization plants located near their source use about the same energy to treat water as do inland water treatment plants, when considering the large energy use for delivering the water from their sources (inland lakes and rivers) to the treatment facilities. The Committee’s conclusion from their findings is that the relative energy consumption for the desalinization process is not “excessive” when compared to other sources of potable water after all is considered. They go on to argue the energy consumption for desalinization for a family of four is about the same as that of their household refrigerator. In summary, they argue,
“Saltwater Reverse Osmosis energy consumption can be relatively high compared to many other water treatment methods. However, when considering the total water/energy equation, including intake source, location, distance, and quality, the power numbers can become quite competitive and perhaps even attractive.”
Table 1:
Source: https://watereuse.org/wp-content/uploads/2015/10/Power_consumption_white_paper.pdf, pg 15.
While the data above is provided by the water treatment industry to show desalinization as a viable cost alternative to pumping large quantities of water through inland systems, there are critics of desalinization who assign more grim financial costs to the desalinization process. According to a late 2017 Forbes article, the cost of electricity in the US was about $0.15 per kWh retail, and $0.05 wholesale. Together with these electricity costs and the claim that farmers in California can currently buy fresh water at $4 per acre foot if they are near the aqueduct, the following list is provided for
“the costs of fresh water today for an acre-foot of fresh water in California:
- $4 (river water from aqueduct)
- $50 (desalinated water, physics limit, wholesale electricity, not yet achieved)
- $150 (desalinated water, at physics limit, retail electricity, not yet achieved)
- $1100 (desalinated water at Santa Barbara California, using best desalination technology available when it was built in the 1980s)”
Of course, the California Aquaduct, part of the California State Water Project, is one of the largest public water utilities in the world. So, it may not be completely fair or accurate to compare all desalinization costs only to the cost of water provided near one 444-mile stretch of water in one state in one country of the world.
With the competing interests of those presenting the costs of desalinization, it is difficult to fully appreciate how desalinization ranks among the options for water treatment. However, energy alone must not be the only means by which to evaluate water treatment options because of the ethical dilemma present in the water scarcity problem. If some people could reduce their power consumption (without undue hardship) so others could have water, should not they do it?
Carbon emissions
The WaterReuse Committee uses an arguably misguided example to defend the carbon emissions related to the desalinization process. They state in a White Paper on energy consumption “the amount of carbon dioxide generated from 3-4 minutes of moderate exercise (e.g., taking the stairs instead of the elevator) is equivalent to the CO2 emissions from a SWRO facility producing one gallon of water for an individual to drink throughout the day.” This comparison is not only misleading, but also is not helpful. It seems to conclude we have a choice to either (a) take the stairs and go thirsty, or (b) never take the stairs and have one gallon of water. That being stated, the carbon emission of the desalinization process (outside the carbon emissions for energy production) is not a hot topic among the critics of desalination. The brine, chemicals, and energy consumption are far more pressing concerns directly related to desalinization, mostly because emissions are a byproduct of the energy production, not the desalinization itself.
Total Financial Cost of Desalinization
In general, the cost of current desalinization efforts has been reported to be in the range of $2.46 – $3.06 per thousand gallons. Though the full analysis of these costs is difficult to perform because the costs are often reported in their best light, and without all the parameters of costing data reported. There are typically large subsidies involved in the costs structure. Additionally, the costs rely heavily on the influent Total Dissolved Solids (TDS). The lower costs reported tend to be in more brackish influent water, which requires lower pressures to treat in an RO facility, and lower energy requirements in a thermal process.
Table 2:
Source:
The Future of Desalinization – Emerging Technologies
In order to more fully examine the feasibility of desalinization as a possible solution to current and future global water demand, it is necessary to not only review the current desalinization processes available, with their associated drawbacks and concerns. The future of desalinization technologies must also be considered, including current research work, and its application to the desalinization processes. The feasibility assessment conclusion drawn will, in the end, include the current state of desalinization and its growth, along with projected reductions in waste, energy consumption, and overall cost.
To that end, below, several technological advancements are reviewed, along with their known benefits and drawbacks. It is difficult to evaluate in this work the full viability of each technology because most things considered are not yet deployed on a full scale. However, the work below will give an indication as to the relative timeline for the implementation for waste and cost cutting measures, given the volume and direction the research efforts are headed.
Reducing Salt Effluents
Farid Benyahia, a chemical engineer at Qatar University, has developed a method of recycling the brine byproduct from desalinization. Farid and his team,
Retooled the 150-year-old chemical conversion method widely used to produce sodium carbonate for industrial applications, simplifying it from seven steps down to just two. Benyahia found that pure carbon dioxide, when mixed with the brine byproduct of desalination in the presence of ammonia, results in solid sodium bicarbonate (baking soda) and ammonium chloride solution. Additional steps break the solution down into calcium chloride solution and ammonia gas, enabling the ammonia to be recycled to start the process all over again.
By simplifying the process, the team has found a way to eliminate the need to put the super salty brine effluent back into the sea, a large volume waste byproduct, and a known drawback of both the thermal and RO processes. While the discovery is currently more expensive than other methods, the team hopes the infrastructure will be developed soon to make the process suitable for better economies of scale. Besides the issue of this process being more expensive, it is not clear from the research available what options are available for dealing with different waste byproducts from this process – calcium chloride and ammonia gas. Those, too, must be disposed of responsibly and sustainably.
Replacing Reverse Osmosis, Finding Lithium
As described above, while reverse osmosis membranes are the most widely used technology in desalinization, the membranes require high pressures to force the seawater through the membranes to active overcome the osmotic pressure of water. The membranes work by being large enough for only the size of a water molecule to pass through, but not the larger sizes of contaminants in the water. Researchers at Monash University, the CSIRO and the University of Texas at Austin have just developed a membrane technology called metal-organic frameworks (MOFs), which are more selective and efficient than RO membranes. “The design was inspired by the ‘ion selectivity’ of biological cell membranes, allowing the MOF material to dehydrate specific ions as they pass through.”
The technology is especially promising because, while seawater is full of lithium salts, the lithium has been difficult to retrieve from seawater. However, MOFs can capture the lithium (and other alkali metal ions) from the seawater. MOFs “boast the largest internal surface area of any known material. Unfolded, a single gram of the material could theoretically cover a football field, and it’s this intricate internal structure that makes MOFs perfect for capturing, storing and releasing molecules (sic).” Other uses for MOFs are being investigated, including using the material carbon emission sponges (essentially absorbing CO2 from the air), or as high-precision chemical sensors, and high volume water filters for urban settings.
MOFs perform this separation of metals from the seawater without the need for large amounts of chemicals or solar ponds, which are expensive and have numerous environmental impacts. Another benefit from MOFs can also be seen in the form of lower pumping power requirements for moving the water through the filter, saving energy. In a sense, MOFs help create energy by providing the lithium ions needed for batteries, and would decrease the need for pulling from land-based lithium reserves. There are no known drawbacks to this technology mentioned in the research. The technology, while promising, is still in a research stage, and the company MOF Technologies is still raising funding to continue their work. This technology may be a major breakthrough in desalinization, but it is too soon to be more certain.
Brackish Water Pools In the Middle East – RE-WRITE
The high costs and the physics limit make it look as if desalination will never be cheap enough for agriculture. But there is a potential loophole: there are cheaper forms of energy than electricity. If you have big ponds of saltwater, you can use solar heating directly. The cost of this approach is not clear, but there are regions in the Middle East where it is being tried with brackish water. They have substituted the cost of maintaining large salt-water pools for the cost of electricity, and it isn’t clear if it can truly be done cheaply enough. Salt water pools have their own problems, including their size, the corrosive power of salt water, and the growth of algae and other plants in the pools.
Solar Desalinization
French technology was deployed in Western Cape (a province of South Africa) in October, 2018 that combines solar technology without a battery with desalinization for the first time. A collaboration of the French and Western Cape governments, the project provides 100 kiloliters of drinking water per day at a cost of R7-8 (~$0.51 – $0.59) per kiloliter. This comes at a cost of far less than the R35-40 ($2.57 – $2.94) per kiloliter provided by the diesel powered desalinization plant in nearby Strandfontein.
Absorption Desalinization (AD)
Adsorption Desalination (AD) may be the most energy efficient desalinization process available now. The technology uses low-grade heat (such as waste heart from a process or solar heat) as its driving force, and it has the added benefit of producing cooling, if needed, for the process. After the seawater is heated slightly, the water vapor adsorbs into a sea of silica until saturated. The bed of silica is then heated using the low grade heat to drive off the desalinated water and condensed into potable water.
The AD process has several advantages over other desalinization processes. The main advantage is, as noted above, the low energy input required to activate the process, particularly if the low-grade heat is heat waste from other processes, such as power plants, manufacturing processes, etc. The system also has few moving parts compared to the high pressure pumping systems RO requires.
The system tends to create less corrosion because the seawater is contained to the first heating area of the process. Finally, the advantage of the cooling effect created by the process cannot be overstated. This would be a great process to co-locate with power plants in particular.
The disadvantage to AD technology at this point is the relative age of the technology. It is not well known and proven yet. However, a full-scale AD / cooling plant is in operation in Riyadh, Saudi Arabia. The plant only produces 100 m3 per day of desalinized water, but is doing so at an energy input of 1.2 kilowatt hour per cubic meter of water produced.
Membrane distillation (MD) – rewrite
Membrane Distillation (MD) is a thermally driven low-energy process that utilizes a hydrophobic, microporous membrane to separate fresh water by liquid-vapor equilibrium. The process is based on the combination of conventional distillation and membrane technologies involving heat and mass transfer.
Preliminary studies have shown that with higher flux hydrophobic membranes can produce good quality water at temperature gradients as low as 10°C between the hot and the cold streams8. However, several major hurdles, including the low permeate flux and low thermal efficiency of MD modules, prevent its mass commercialization. More research is needed to develop novel MD membranes with high throughput to increase the permeate flux and thermal efficiency by using industrial waste-heat or by incorporating the direct use of solar energy.
Forward Osmosis – rewrite
Forward osmosis (FO) processes can be used directly or indirectly to make the desalination process more energy efficient. Indirect FO desalination processes use low salinity feed solution like wastewater to dilute higher salinity seawater and produces partially desalinated water, which can be used for irrigation. Ongoing research shows that the fouling on membrane surfaces is lower while a complete removal of contaminants, such as micropollutants, natural organic matter, trace metals and nutrients from the feed water is possible11 12. However, there are still a number of aspects that need to be explored before the technology can be applied for commercial production in the Middle East. The development of high throughput FO membranes will be a breakthrough towards process scale-up and commercialization.
As the demand for fresh water grows in the Middle East, the future of desalination will depend on combining established and emerging technologies. Researchers need to focus on the hybridisation of forward osmosis (FO), membrane distillation (MD), and adsorption desalination (AD) coupled with and without conventional desalination processes such as thermal desalination and reverse osmosis.
This combination will assist the development of energy efficient and renewable energy-driven desalination technologies. Besides development of energy efficient and environment-friendly desalination technologies, good planning and management of water resources is essential. There is a huge potential in reusable water techniques to improve utilization of treated domestic and industrial wastewater to produce ample fresh water supplies.
Projected Use of Desalinization
Currently, approximately 150 (out of 195 UN recognized) countries rely on desalination to meet their fresh water demands. Around the globe, about 80 million m3 (~ 21 billion gallons) of potable water is produced daily by over 17,000 desalination plants, with 50% of these utilizing seawater as the source (as opposed to brackish). Of these 17,000 plants, about 70% are located in the Middle East. Saudi Arabia alone produces about 20% of the world’s desalinized water. One explanation for the tremendous growth in water demand (and thus, the need for desalinization plants), is the shift in the Middle East and Africa economies from oil and gas industries to tourism and manufacturing. Tourism and manufacturing brings with it the demand for fresh water for construction and industrial activities. The same trend is expected in China and India as their economies develop over the coming decades. Other countries, such as Algeria, Australia, Bangladesh, Belgium, Brazil, and Canada, have already planned construction of desalinization plants as they look ahead to projected economic growth and its association increased water demand.
Regarding the use of desalinization technology, while 70% of thermal process plants have transitioned to RO elsewhere around the world, only 50% of plants in the Middle East are using RO processes. This leaves much room for growth in the way of technological advances to reduce energy and waste. More research is in progress for RO technology for the warm temperatures and saltier water of the Middle East. As of now, the membranes are not yet a mature technology for the area.
Even so, RO has the major stake in desalinization technology, with more than 60% of the market share in 2017, with energy requirements being the primary reason for the preference over thermal processes.
Presence of small and large desalination plants around coastal areas has resulted in maximum filtration of seawater making it the largest application segment. Seawater desalination is expected to witness the largest growth on account of their vast reserves and easy accessibility. Presence of limited brackish water sources are also expected to play an important role in bolstering the use of seawater.
The global desalination market is highly fragmented in nature with the presence of medium and large scaled companies. Companies such as Doosan Heavy Industries, Veolia Enivronnement, Suez Environnement, and GE are some of the large companies with a global presence, whereas, Fisia Italimpianti, Hyflux, and Aquatech have a region-specific presence. However, each of these companies is moving towards improving their desalination technology in order to reduce the overall production cost, thereby, expanding and strengthening their presence in the global industry.
The global desalination market is likely to expand at a CAGR of 7.8% from 2018 – 2025. Rapid industrialization coupled with increasing population has led to the development of technologies including water desalination equipment that are capable of harnessing ground saline water and seawater, thus making it suitable for human consumption. Over the past few years, desalination has become an integral part of water management strategies including wastewater reuse in several countries across the world.
Israel Leads the Charge
In mid-2018, Israel announced its plans to be fully dependent on desalinization as its source of drinking water processing by 2023. With the nation already producing 600 million cubic meters of water annually (70-80 percent of its water), the goal is far off in the distance. IDE Technologies, an Israeli water company, employs reverse osmosis to process seawater from the Mediterranean Sea, at, what it claims to be, a low cost and a low energy consumption level. The company has built three desalinization plants in Israel, with one of the plants being the highest capacity plant in the world. All told, Israel has five desalinization plants, with plans to build two more plants in the next four to five years to meet its goal.
Another way Israel is leading the charge toward desalinization is by establishing desalinization drinking water standards for the addition of essential minerals back into the water after treatment. The Israeli Drinking Water Committee has recognized the importance of at four minerals vital for human health, including magnesium, iodine, fluorine, and calcium. Currently, only the calcium is added back in the water in Israel. However, as concern rises among the public, the addition of magnesium is being considered.
Cost Reduction Measures
Overall, the cost reduction measures taken over the past 20 years have made desalinization into a financially viable option for many locations already. And, there are expectations future savings will be garnered through advancements in technology in every facet of desalination, e.g. positive displacement pumps replacing less efficient centrifugal pumps as the technology allows for larger throughputs. With so many stakeholders (i.e. plant owners, plant operations, academia, the public consumer, industrial consumers, action groups, nation-states, etc.) in the interest of having clean water available around the world, much effort will be expended on optimizing each input and output to the process to reduce cost, and waste. Most of the effort is more pragmatic than altruistic, yet the result is the same – more clean water at a lower financial, environmental, and social cost.
According to Global Water Intelligence, operating costs of desalinization plants have fallen over the last 20 years, from an average cost per cubic meter of water of $1.50 to less than $0.75. In addition to lowering the operating costs, the capital startup costs have also declined significantly. Specific to energy costs, during the same 20 year period, the energy inputs to the desalinization process have reduced by 80 percent. As noted above, the energy needed to produce fresh waster for a household for one year is now less than the energy required for a refrigerator in the home (~2,000 kWh/yr).
Interestingly, the International Water Association paints a conservative picture for the growth of technological advancements for the next five years. However, over the longer run (20 years+), they expect costs to be at least 60% lower than today. They state:
No major technology breakthroughs are expected to dramatically lower cost of seawater desalination in the next several years. But the steady reduction of production costs, coupled with increasing costs of water treatment driven by more stringent regulatory requirements, are expected to accelerate the current trend of increased reliance on the ocean as a water source. This will further establish ocean water desalination as a reliable, drought-proof alternative for many coastal communities worldwide. Technology advances are expected to reduce the cost of desalinated water by 20% in the next five years, and by up to 60% in the next 20 years (see Table 1), making it a viable and cost-effective competitor for potable water production.
Conclusion
References