The Rockfeller Foundation supported Cities‘ Ruth Michaelson wrote from Riyadh, Saudi Arabia on Tue 6 Aug 2019 the following article that elaborates on water increasing scarcity in Saudi Arabia and how despite that, life carries on somehow unaffected.
As Riyadh continues to build skyscrapers at a dizzying rate, an invisible emergency threatens the desert kingdom’s existence
Bottles of water twirl on the conveyor belts of the Berain water factory in Riyadh, as a puddle of water collects on the concrete floor. In a second warehouse, tanks emit a low hum as water brought in from precious underground aquifers passes through a six-stage purification process before bottling.
“In Saudi Arabia, there are only two sources of water: the sea and deep wells,” says Ahmed Safar Al Asmari, who manages one of Berain’s two factories in Riyadh. “We’re in the central region, so there are only deep wells here.”
Most water withdrawn comes from fossil deep aquifers and predictions suggest these may not last more than 25 years: UN
Perhaps not surprising for someone who makes a living selling water, Asmari professes to be untroubled about the future of Saudi Arabia’s water supply. “Studies show water in some reserves can stand consumption for another 150 years,” he says. “In Saudi Arabia, we have many reserves – we have no problems in this area.”
His confident predictions are out of sync with the facts. One Saudi groundwater expert at King Faisal University predicted in 2016 that the kingdom only had another 13 years’ worth of groundwater reserves left.
“Groundwater resources of Saudi Arabia are being depleted at a very fast rate,” declared the UN Food and Agriculture Organisation as far back as 2008. “Most water withdrawn comes from fossil deep aquifers, and some predictions suggest that these resources may not last more than about 25 years.”
In a country that rarely sees rain, the habit of draining groundwater, like the Berain factory does, could prove perilous: groundwater makes up an estimated 98% of naturally occurring fresh water in Saudi Arabia.
Indeed, oil may have built the modern Saudi state, but a lack of water could destroy it if drastic solutions aren’t found soon.
The emergency seems invisible in Riyadh, which is undergoing a construction boom as more buildings creep upwards to join a collection of towering skyscrapers.
It’s the desert. Obviously, water is a natural constraint by Dr Rebecca Keller
Although everyone knows this city in the desert owes its existence to the discovery of oil in 1938, fewer realise water was just as important. Decades of efforts to make the desert bloom to feed the city’s population have resulted in agricultural projects to grow water-intensive crops such as wheat, on farmland meted out to figures favoured by the royal family.
While many questions the accuracy of the kingdom’s optimistic estimates of its own oil reserves, the looming threat of a lack of water could prove to be an even bigger problem. Saudi Arabia consumes double the world average of water per person, 263 litres per capita each day and rising, amid a changing climate that will strain water reserves.
In March, the Kingdom launched the Qatrah programme to demand citizens drastically cut their water use. Its aim is to ration water to 200 litres per person per day by 2020 and 150 litres by 2030.
It has also tried to reform the water-hungry agriculture industry, reducing government incentives for cereal production. The overall amount of irrigated farmland still hasn’t declined, though, as producers switch to more profitable crops that still require large amounts of water. Almarai, a major food producer, has begun buying up deserted land in the US, on plots near Los Angeles and in Arizona, and in Argentina, in order to grow water-rich alfalfa to feed its dairy cows.
The Saudi Arabian National Transformation Plan, also known as Vision 2020 – a subset of the Vision 2030 initiative intended to diversify the Kingdom’s economy away from oil – aims to reduce the amount of water pulled from underground aquifers for use in agriculture. It seeks to employ 191% of these water resources for farming, down from the current estimates of 416% of water available.
“This means that Saudi Arabia is using more than four times the water that renews on average – and that’s in Vision 2020,” says Dr Rebecca Keller from Stratfor – a private intelligence and geopolitical analysis firm – who says she was shocked after learning about the country’s water use. “Technically they’re using fossil water, which renews at a really, really slow rate. The sheer volume of overuse stood out to me.”
Desalinating sea water has long been seen as a silver bullet against the growing threat of water shortages across the Middle East. Saudi Arabia leads the world in the volume of desalinated water it produces and now operates 31 desalination plants. Desalinated water, as distinct from naturally occurring fresh water, makes up 50% of water consumed in Saudi Arabia. The remaining 50% is pulled from groundwater.
It comes as at a high-energy cost, however. According to the International Energy Agency, in 2016 desalination accounted for 3% of the Middle East’s water supply but 5% of its overall energy cost. Researchers at King Abdelaziz University in Jeddah estimate that the demand for desalinated water increases by roughly 14% each year, but add that “desalination is a very costly process and is not sustainable”. Desalination plants also harm the surrounding environment, pumping pollutants into the air and endangering marine ecosystems with their run-off.
A recent push towards using solar power rather than fossil fuels to desalinate means that the first commercial plant is expected to be up and running at 2021 at the earliest, although it reportedly remains behind schedule.
Keller says Saudi Arabia’s evolving use of desalination technology could also alter their relationship with other countries in the region, in particular, Israel. “They’re producing the most cutting-edge technology for desalination, especially at scale,” she said. “As we see [both countries] having more geopolitical things in common in terms of their attitude to Iran, there’s more room for this relationship to grow, and the Saudi water sector is something that could benefit from this cooperation.”
The toughest challenge of all remains switching consumption habits to avoid an impending water emergency. The kingdom is pressing ahead with its Red Sea Project, a tourism haven the size of Belgium that aims to attract a million visitors annually to its unspoiled beaches and 50 new hotels. Such mammoth construction means growing water use, with current estimates that the string of resorts will use 56,000 cubic metres of water per day.
“It’s the desert,” said Keller. “Obviously water is a natural constraint.”
This article is significant news in the MENA region; the most water-scarce region in the world, where desalination plants are for some time now ‘run of the mill’ urban furniture. An improvement in the filtering membrane would have a financial impact on the running costs of these plants. It could encourage the inception of more especially in those other and remote areas with limited finances. A new filter turning saltwater into freshwater upgrade would undoubtedly impact not only this water industry but also all those linked with the region’s agriculture and food production.
“Making the material smoother prevents it from getting gunked upquickly”, as per Maria Temming, author of this article posted on August 16, 2018, by ScienceNews would certainly not fall in deaf ears whether from these last referred to countries but from all of the MENA region. The only snag would be that of whether sea water rising could suffice to feed all those prospective plants.
SMOOTH MOVE Hundreds of millions of people rely on desalinated water from plants like this one in Dubai. A new-and-improved salt-filtering material could help make freshwater production more affordable. Stanislav71/Shutterstock
Smoothing out the rough patches of a material widely used to filter saltwater could make producing freshwater more affordable, researchers report in the Aug. 17 Science.
Desalination plants around the world typically strain salt out of seawater by pumping it through films made of polyamide — a synthetic polymer riddled with tiny pores that allow water molecules to squeeze through, but not sodium ions. But organic matter, along with some other waterborne particles like calcium sulfate, can accumulate in the pockmarked surfaces of those films, preventing water from passing through the pores (SN: 8/20/16, p. 22). Plant operators must replace the membranes frequently or install expensive equipment to remove these contaminants before they reach the filters.
Now researchers have made a super smooth version without the divots that trap troublesome particles. That could cut costs for producing freshwater, making desalination more broadly accessible. Hundreds of millions of people already rely on desalinated water for drinking, cooking and watering crops, and the need for freshwater is only increasing (SN: 8/18/18, p. 14).
Manufacturers normally create salt-filtering films by dipping porous plastic sheets into chemical baths that contain the molecular ingredients of polyamide. These molecules glom onto the sheet, building up a thin polymer membrane. But that technique doesn’t allow much control over the membrane’s texture, says Jeffrey McCutcheon, a chemical engineer at the University of Connecticut in Storrs.
McCutcheon and colleagues made their version by spraying the polyamide building blocks, molecular layer by layer, onto sheets of aluminium foil. These polyamide films can be up to 40 times smoother than their commercial counterparts.
Such ultra-smooth surfaces should reduce the amount of gunk that accumulates on the films, McCutcheon says, though his team has yet to test exactly how clean its films stay over time.
Typical polyamide films for filtering saltwater (shown in the scanning electron microscopy image to the left) have rugged, pockmarked surfaces that trap organic material and other particles, clogging the filter. New, ultrasmooth polyamide membranes (right) could avoid that problem.
A microscopic image of two polyamide films for filtering saltwater M.R. CHOWDHURY ET AL/SCIENCE 2018
Mark Zeitoun, Professor of Water Security, University of East Anglia andGhassan Abu Sitta , Founder, Conflict Medicine Program, American University of Beirut are the authors of this article that we republished here with our compliments.
Gaza has often been invaded for its water. Every army leaving or entering the Sinai desert, whether Babylonians, Alexander the Great, the Ottomans, or the British, has sought relief there. But today the water of Gaza highlights a toxic situation that is spiralling out of control.
A combination of repeated Israeli attacks and the sealing of its borders by Israel and Egypt, have left the territory unable to process its water or waste. Every drop of water swallowed in Gaza, like every toilet flushed or antibiotic imbibed, returns to the environment in a degraded state.
When a hospital toilet is flushed, for instance, it seeps untreated through the sand into the aquifer. There it joins water laced with pesticides from farms, heavy metals from industry, and salt from the ocean. It is then pumped back up by municipal or private wells, joined with a small fraction of freshwater purchased from Israel, and cycled back into people’s taps. This results in widespread contamination and undrinkable drinking water, about 90% of which exceeds the World Health Organisation (WHO) guidelines for salinity and chloride.
Incredibly, conditions are getting worse, thanks to the emergence of “superbugs”. These multi-drug resistant organisms have developed thanks to an over-prescription of antibiotics by doctors desperate to treat the victims of the seemingly endless assaults. The more injury there is, the more chance there is of re-injury. Less regular access to clean water means infections will spread faster, bugs will be stronger, more antibiotics will be prescribed – and the victims will be ever-more weakened.
The result is what has been termed a toxic ecology or “biosphere of war”, of which the noxious water cycle is just one part. A biosphere refers to the interaction of all living things with the natural resources that sustain them. The point is that sanctions, blockades and a permanent state of war affects everything that humans might require in order to thrive, as water becomes contaminated, air is polluted, soil loses its fertility and livestock succumb to diseases. People in Gaza who may have evaded bombs or sniper fire have no escape from the biosphere.
It’s not as if there is no fresh water nearby to alleviate the situation in Gaza. Just a few hundred metres from the border are Israeli farms that use freshwater pumped from Lake Tiberias (the Sea of Galilee) to grow herbs destined for European supermarkets. As the lake is around 200km to the north and lies 200 metres below sea level, a massive amount of energy is used to pump all that water. The lake water is also fiercely contested by Lebanon, Jordan, Syria and Palestinians in the West Bank, each of which is seeking their legal entitlement of the Jordan River basin.
Meanwhile, Israel desalinates so much seawater these days that its municipalities are turning it down. Excess desalinated water is being used to irrigate crops, and the country’s water authority is even planning to use it to refill Tiberias itself – a bizarre and irrational cycle, considering the lake water continues to be pumped the other direction into the desert. There is now so much manufactured water that some Israeli engineers can declare that “today, no one in Israel experiences water scarcity”.
But the same cannot be said for Palestinians, especially not those in Gaza. People there have resorted to various ingenious filters, boilers, or under-the-sink or neighbourhood-level desalination units to treat their water. But these sources are unregulated, often full of germs, and just another reason children are prescribed antibiotics – thus continuing the pattern of injury and re-injury. Doctors, nurses, and water maintenance crews meanwhile try to do the impossible with the minimal medical equipment at their disposal.
Right now raw sewage is flowing into the Mediterranean Sea amid the Gaza Strip’s electricity crisis. #unrwalive
The implications for all those who invest in Gaza’s repeatedly destroyed water and health projects are clear. Providing more ambulances or water tankers – the “truck and chuck” strategy – might work when conflicts are at their most acute, but they are never more than a band aid. Yes, things will get better in the short term, but soon enough Gaza will be onto the next generation of antibiotics, and dealing with teflon-coated superbugs.
Donors must instead design programmes suited to the all-pervasive and incessant biosphere of war. This means training many more doctors and nurses, providing more medicines, and infrastructure support for health and water services. More importantly, donors should build-in political “cover” to protect their investments (if not the local children), perhaps by calling for those who destroy the infrastructure to foot the bill for repairs.
And there is an even bigger message for the rest of us. Our research shows that war is more than simply armies and geopolitics – it extends across entire ecosystems. If the dehumanising ideology behind the conflict was confronted, and if excess water was diverted to people rather than to lakes, then the easily avoidable repeated injuries suffered by people in Gaza would become a thing of the past. Palestinians would soon find their biosphere a whole lot healthier.
Somebody the other day in an Investment Website introduced his counselling thus : You’ve got rather used to turning on the tap, and having water come out. You probably think that our water supply is fairly reliable. But you’d be wrong. More specifically in the MENA region, the issue has always been throughout the centuries there. Globally, nowadays, water is in a crisis – and it could affect you far sooner than you think. Let’s get this problem into perspective. Start by listing all the things you use water for. You’ll probably quickly add showering, washing clothes, and drinking. But if you think that’s captured your main use of water, I’m afraid you’re entirely wrong. The vast majority of the water you use isn’t in the home at all – it’s “embedded” in the products you buy. For example, it takes nearly two-and-a-half tonnes of water to make one hamburger. This isn’t all drinking water – but it’s still needed for the farming and manufacturing processes. Surprised?
Seriously, the problem is real and who best to explain to us all those related issues than the following.
The UNDP produced this article in 2006 on Water Scarcity Challenges in the Middle East and North Africa by Stockholm International Water Institute.
Water is scarce in the Middle East and North Africa (MENA) region. As Allan (2002) noted, the region basically “ran out of water in the 70s” and today depends as much on water from outside the region — in the form of its food imports, for example — as on its own renewable water resources.
We also know that using desalination, Saudi Arabia, the largest producer of desalinated water in the world had in 2011 the volume of water supplied by its 27 desalination plants at 17 locations, 3.3 million m3/day (1.2 billion m3/year). 6 plants are located on the East Coast and 21 plants on the Red Sea Coast.
The following article written in June 15th, 2016 by Pilar Buzzetti contributed to this worrisome and omnipresent problem of water supply issue in the MENA region.
Water in the MENA, a source for conflict or a source for peace?
The scarcity of water is not something new for an arid region like the MENA. Despite MENA countries represent 7 percent of the world population, they count on less than 1.5 percent of the world’s freshwater resources. Furthermore, in the light of the population growth in recent years, the shortage of water has become a serious challenge.
The complexities of managing and sharing common water resources are well known to the region. Continued and constant water scarcity is likely to affect the region’s social and economic potential, increasing land vulnerability to desertification and raising the risk for political conflict around the limited available water. Conflicts over water in both intranational and international settings evolve in complex political and hydrological environments. The potential for conflict is increasing in the region because of the highest demographic concentrations found in the region, such as in the Gaza strip.
Water dependency is clearly rather high for many countries in the area. Transboundary water issues are leading to water conflicts. Countries like Syria, Jordan and Palestine rely on water resources that lie beyond their borders; for example, Palestine is almost entirely dependent on water essentially controlled by Israel. The transboundary nature of the water resources in the Middle East makes cooperative management of these resources critical as they have the potential to induce economic and social development and reduce the risks of conflict. Despite significant investment in the water sector, water management still remains a serious economic and environmental problem in MENA countries, affecting public health and agricultural productivity. The environment as well is suffering due to the over-pumping of the aquifers and the deterioration of water quality.
The region is already struggling with other key political challenges, including the Arab-Israeli conflict, Iran’s foreign and regional politics and the results of the social awakenings. Surely, the region is tinkering on the verge of a socio-economic repression due to a mixture of climatic change effects, economic challenges and post-Arab spring political instability. It is clear how potable water shortages together with lack of proper sanitization, represent key daunting challenges. Even more, the region’s consumption of natural resources is more than double of what regional ecosystems can support, putting the region on a brink of “ecosystem bankruptcy.” The issue of water shortage is strictly linked to national security affairs, since water plays a pivotal role across the various sectors and it is obstinately regarded as a determining factor to the region’s economic development and socio-political stability. . . .
Water Security in the Middle East and North Africa
According to the World Resources Institute (WRI), the MENA region is one of the most water insecure regions of the planet and that “roughly two thirds of the Arab World’s surface water supplies originate outside the region” and as put by Amit Pandya, Stimson Centre Fellow and Cipher Brief expert, would require extensive cooperation between regional countries to manage. Water Security in the MENA region should consequently be at the top of the elites’ agendas and second to none.
Water resources, as aggravated by global climate change, local populations’ explosion, and non-ending regional conflicts, not only continue to outstrip supply but also make it difficult to store and rationally distribute the little of that is available.
Amit Pandya in a write up of August 19th, 2016 that is reproduced below, observed, that perhaps the most important first step will be to “avoid wringing our hands at the impossibility of reversing large scale natural processes and understand water as a resource that is, has been, and should be managed.”
In 2016, the Middle East and North Africa (MENA) region has experienced record-setting high temperatures. This is seen by meteorologists as part of a steady trend that will not abate and has led experts to predict that stress on water endowments and supplies in the region could in turn spur conflict and population displacement in the world’s most water-scarce region. As populations grow, per capita water demand rises and global climate change intensifies. Per capita water availability in the MENA region is projected to halve by mid-century.
Water is, of course, essential to human life. In a region that is the locus of some of the world’s most intense and complex conflicts, water should therefore be placed at the center of security discourse and planning. There has certainly been some attention to the security implications of water and related economic and governance issues. However, immediate political and ideological developments have understandably dominated the mainstream security discourse, particularly among policy makers, and have obscured equally important issues such as water, environmental change, and economic and demographic trends. These have largely remained specialist interests. This must change if adequate and responsive policies are to be developed by the international community and by those powers, such as the United States, with a stake in the region.
Managing water has been fundamental to the development of human societies in the Middle East and North Africa. The role of the Nile in Egyptian civilization, from antiquity to the present, is axiomatic, and the role of water management in the rise of civilization itself is reflected in the legal codes of ancient Mesopotamia, where the Codes of Ur-Nammu and Hammurabi, dating back four millennia, set rules for the proper use and maintenance of common water works.
This suggests that we should avoid wringing our hands at the impossibility of reversing large scale natural processes and understand water as a resource that is, has been, and should be managed. Accordingly, we need to emphasize the importance of water policy, both within and from outside the region.
Meeting the challenge will require enhanced innovation and reform within the water policy communities and economies of the MENA countries, as well as increased cooperation, data sharing, knowledge, and capacity building between them, and a recognition by the international community of its responsibility to support these efforts.
Annual renewable water supplies in MENA are approximately 620 billion cubic meters (BCM), compared to Africa’s almost 4000 BCM, Asia’s 12,000 BCM, and a world total of approximately 43,000 BCM. MENA’s per capita annual water availability is estimated by water experts to be only around two thirds of the amount that is needed to prevent a significant constraint on socio-economic development, making the region the most water stressed in the world. Indeed, many MENA countries suffer from levels as low as 10 percent of the MENA regional figure. The region has approximately seven percent of the world’s population and less than 1.5 percent of the world’s renewable freshwater supply. At the same time, richer states, like members of the Gulf Cooperation Council (GCC), have some of the highest per capita water consumption rates in the world.
This scarcity is compounded by population growth, migration, industrialization, urbanization, pollution, and climate and other environmental change, along with the proliferation of energy-intensive lifestyles. Growing water demand, decreasing water availability, and deteriorating water quality are the result.
Issues of water scarcity and choices about water policies affect farming (crop choice, growing seasons, and pests), fisheries, forestry, livestock, hydropower, and industry, all of which have an impact on agricultural production, food security, and rural and urban livelihoods. Competition among uses, such as irrigation, municipal uses, and energy production, can damage public health and social welfare, thus creating political instability and posing significant internal security risks.
Some MENA countries have low levels of renewable water resources, such as flowing rivers, and must rely on groundwater and desalination for most of their supply. Others get much of their water from river systems they share with other countries. The former group includes Bahrain, the Gaza Strip, Kuwait, Oman, Qatar, Saudi Arabia, the United Arab Emirates (UAE), and Yemen. The latter Egypt, Iraq, Iran, Jordan, Lebanon, the West Bank, Sudan, and Syria.
Much of the MENA region relies upon transboundary water resources. International competition and conflict are inevitable and have, in many cases, already occurred. However, these shared resources can also be occasions for unprecedented cooperation, given the urgent need for water.
Two-thirds of the Arab world’s surface water supplies originate outside the region. Roughly 90 percent of the Euphrates’s annual flow, for instance, and half of the Tigris’s water supply rises in Turkey. More than half of Iraq’s renewable water originates outside the country. Sudan and Syria receive some three quarters of their water from beyond their borders; and Bahrain, Egypt, and Kuwait depend on external sources for more than 95 percent of their renewable freshwater.
In addition, underground water resources, including fossil water, are little noticed or discussed by non-specialists. Significant transboundary aquifers in the region include the Nubian Sandstone Aquifer beneath Egypt, Libya, Chad, and Sudan; the Northwestern Sahara Aquifer System underlying Algeria, Libya, and Tunisia; and the Basalt Aquifer shared by Jordan and Saudi Arabia.
Several MENA countries derive one-third or more of their water supplies from underground reservoirs. But many states are depleting their groundwater at an unsustainable rate. Annual withdrawals exceed 108 percent of renewable resources in Iran, 350 percent in Egypt, 800 percent in Libya, and 954 percent in Saudi Arabia. When these water sources cross political boundaries, it is easy to see sources of conflict at such ruinous rates of withdrawal.
As with river systems, countries and other entities will need to better map and assess groundwater resources, and negotiate policies for its extraction, its sustainable management, and its equitable allocation.
Some water strategies that have been adopted in MENA — such as desalinization in the Gulf and dam construction on the major river systems — have side-effects that pose additional environmental, economic, and social stresses. Other strategies, such as Integrated Water Resource Management (IWRM), are models of skillful and successful management, in Oman for example.
A modest but substantive approach by the international community to address these issues might consist of technical assistance and financing for water quality monitoring and improvement, climate change adaptation, community and stakeholder participation, and knowledge sharing.
The last should be focused around cooperation and exchange between institutions within MENA, such as the Arab Integrated Water Resources Management Network (AWARENET), and national and regional scientific institutions, such as the Islamic World Academy of Sciences and the Sahara and Sahel Observatory. However, institutions and governments from outside the region also have much to contribute in this respect.
Amit A. Pandya is a non-resident Fellow at the Stimson Center. He is an international lawyer whose research interests include social, environmental and economic trends in the Arab world and South Asia. He has served as Counsel to Subcommittees on National Security and International Operations in the U.S. House of Representatives, Director of the Humanitarian Assistance Office in the U.S. Department of Defense, Deputy Assistant Administrator for Asia and the Near East at the U.S. Agency for International Development, a member of the Department of State’s Policy Planning Staff and Chief of Staff to the International Labor Affairs Bureau of the U.S. Department of Labor.
An article of POWERMAG written by Kennedy Maize and published on 1 March 2016is about water desalination, and how to go about producing it. Some sort of Clean Water Desalination dilemma is on going.
Excerpts of the article titled Desalination Expands, but Energy Challenges Remain are proposed here below.
Unfortunately like for most good things, desalinated water comes at a fairly high price in terms of amount of energy used usually of the fossil type and its consequent carbon footprint. Ways and methods of alleviating these are being researched throughout the world and this would obviously interest the MENA countries perhaps more than any other countries in the world.
. . . At the ballyhooed Paris climate conference (COP21) last December, a little-noticed event occurred that could lead to important developments for electric generators. At the Paris meeting, some 80 signatories— including national governments, energy and water industries, research groups, universities, and nongovernmental organizations— launched the Global Clean Water Desalination Alliance. The group’s focus, which it calls “H2O minus CO2,” is on how to reduce carbon dioxide emissions from the energy intensive process of turning seawater into a potable product. A press release from Paris announcing the organization’s founding noted that access to clean water is “already a major challenge for as much as one-quarter of the world’s population,” and that some forecasts are “predicting that by 2030, 47% of the global population will face water scarcity.” It’s not that the world is short of water—which covers some 70% of the planet’s surface and is entirely renewable—but that most of it is seawater. . . .
Separating salts and other impurities from H2O is a well-understood process with a long history. Desalination of seawater, brackish water, and recycled water is widely practiced around the world in a variety of ways. Generally, two types of separation technologies—thermal and membrane—dominate, each with about half of the global market (for a more detailed discussion, see “Adding Desalination to Solar Hybrid and Fossil Plants” in the May 2010 issue online at powermag.com).
Thermal technologies use heat to vaporize seawater, condensing the steam as pure water. The three approaches used with thermal desalination are multi-stage flash distillation (MFD), multi-effect distillation (MED), and vapor compression distillation (VCD). In MFD, feedwater is heated under high pressure and then flows as a liquid into a successive series of chambers with progressively lower pressures. Because each stage is lower in pressure than the one before, the liquid water continues to flash to steam, which is collected by heat exchange tubing running through each stage. MFD technology dates to the 1950s. MFD plants dominate the thermal sector, and many have been built in the Middle East, where water is scarce but energy resources are cheap and plentiful. MED was first used in the late 1950s and early 1960s. In MED plants, a series of evaporator vessels are held at progressively lower temperatures and pressures. Because the boiling point of water decreases as pressure decreases, the vapor boiled off in one vessel can be used to heat the next, and only the first vessel requires an external source of heat. Three MED plants with combined capacity of 3.5 million gallons (13,250 m3) per day operate in the U.S. Virgin Islands, serving as the principal water supply. VCD uses heat from compression of vapor, rather than an external heat source. Typically, a mechanical compressor is used, often powered by a diesel engine. These desalination units are generally small and can be used at hotels, resorts, and in industrial applications.
Membrane Desalination Membrane technologies separate salts from water using exceptionally fine screens or membranes. The two categories are electro dialysis (ED) and reverse osmosis (RO). ED, introduced in the 1960s, is voltage driven and generally used for treating brackish water. Most salts dissolved in water are negatively or positively charged ions. The technology uses electrodes of opposite charge to attract the ions, with membranes to permit selective passage of either positively charged cations or negatively charged anions. An ED stack consists of several hundred such cells that the feed water is pumped through. RO is the latest technology, commercialized in the 1970s and based on Israeli research and development. It is the most widely used desalination technology in the U.S. This process reverses normal osmosis—in which a solvent moves from zones of low solute concentration to zones of high concentration—by applying pressure to the zone of high concentration. This causes the pure solvent—in this case, purified water—to flow continuously to the low-concentration side of the membrane. RO works for both seawater and brackish water, and removes all impurities, not just salt. ED and RO can be used together, with the ED stack treating both the RO feed water and its brine stream. . . .
That’s where the alliance announced in Paris—led by Masdar, the United Arab Emirates’ (UAE’s) renewable energy company, and the International Desalination Association—comes in. The alliance said its “goal is to seek solutions that will substantially reduce the projected increase in CO2 emissions from the desalination process, as global demand for drinking water continues to grow.” The group said it is seeking “a decrease in emissions from 50 [million tons of CO2] up to as much as 270 [million tons] per year by 2040.”. . .
Government-owned Masdar last November began development on a pilot seawater desalination plant using solar energy, which the company says it will run at small scale for 15 months. “These technologies have never been used on a utility scale anywhere in the world,” said Masdar. Just days after the announcement at the Paris COP21 meeting, the UAE and China signed a deal to work together to combine Masdar’s desalination technology with low-cost solar photovoltaic technology developed in China.
There are currently about 15,000 desalination plants operating around the world, with the largest in Saudi Arabia, the UAE, and Israel. The Saudi Shoaiba complex produces over 232 million gallons (880,000 m3) daily, while the Al Jubail complex produces over 211 million gallons (800,000 m3) per day. The big Saudi plants use a variety of desalination technologies. . . .
What’s Ahead for Desalination ?
Massachusetts Institute of Technology (MIT) researchers are testing a new approach to desalination that relies neither on energy-intense thermal distillation nor RO membrane technology, which can clog and decrease the efficiency of the process. According to a university press release, “Instead, the system uses an electrically-driven shockwave within a stream of flowing water, which pushes salty water to one side of the flow and fresh water to the other, allowing easy separation of the two streams.”
MIT professor Martin Bazant says the approach is “a fundamentally new and different separation system.” It is a continuous process that Bazant claims may be relatively easy to scale up. According to MIT, one of the uses for the technology could be to clean up the large amounts of wastewater generated by hydraulic fracking for gas and oil.
More conventionally, researchers at Egypt’s Alexandria University are looking at a combination of low-tech filtration and evaporation, which could lower desalination power requirements. In a paper in the September edition of the journal Water Science & Technology, the researchers describe a filtration technique known as “pervaporation,” which passes saline water through a fairly simple membrane to remove large molecules and then vaporizes the filtered water. The technology is now used in wastewater treatment to separate organic solvents from the water stream.”
Further reading and details are at http://www.powermag.com/desalination-expands-energy-challenges-remain/