If you’re ever lost in a desert, finding a water supply is key to your survival. Understandably, this is difficult in a desert as there is neither enough rainfall nor open-water sources, such as rivers or lakes, to reliably support the people inhabiting these areas. What many desert regions do have, however, are coastlines with access to plenty of salty seawater.

Enter desalination.

Desalination is a brilliant way to make fresh water. Seventy percent of the world is covered with water, but only 1 percent of that is potable. The solution? Take the salt out of the sea.

In the United Arab Emirates, even the groundwater is saline, in some cases up to eight times as salty as the surrounding seawater. Although this brackish groundwater can be used in irrigating salt-tolerant plants like date palms, everything else needs that water to be desalinated.

IMAGE: Anas Albounni, KUST Review

A harsh legacy of waste

“Historically, water availability has always been considered fundamental for human civilizations to evolve and flourish, from the early Mesopotamian age to the current rapidly growing cities in the Middle East. Read more›››

“Over time, wasteful water use, mismanagement and significant environmental challenges have triggered severe depletion and degradation of the available freshwater resources, with adverse effects on human health, living conditions, and social and economic prosperity.”

Tom Pankratz, Global Water Intelligence‹‹‹ Read less

In many ways, the Middle East is on the cutting edge of sustainability because the governments there were forced to confront water scarcity from the get-go. The evolution of water conservation and sustainability in this region is a result of a multi-pronged approach, involving rethinking city planning, efficient water use and innovative solutions to providing clean water.

A PERFECT FIT

Desalination plants are found in abundance in the Middle East: The U.S. Geological Survey says 70 percent of the world’s desalination plants are located in this area, found mostly in Saudi Arabia, the UAE, Kuwait and Bahrain. This makes sense: These countries are water-strapped but oil-rich. An energy-intensive clean-water-production technique is a perfect fit.

This oil won’t last forever, though. And the world is already feeling the effects of global warming and climate change thanks to rampant use of fossil fuels in applications including desalinating water for desert populations. The solution? “Renewabilize” it. And luckily, the Middle East also has plenty of renewable energy to spare: sunshine.

RELATED: Desalination has social benefits – and costs, too

But first, how does desalination work?

The most popular method is reverse osmosis, where large quantities of seawater are pushed through a semipermeable membrane to remove the salt from the water. Think of this membrane as a very fine sieve that catches salt and other impurities.

Although this is an effective means to desalinate seawater, it is driven by very high hydraulic pressure and requires robust pumping and expensive pretreatment. In Saudi Arabia’s Eastern Region, for example, the seawater first needs to be filtered for oils, greases and jellyfish.

IMAGE: Shutterstock

What to do
with the brine?

Brine is a high-concentration solution of salt in water and is a byproduct of many industrial processes, including desalination. The simplest way to dispose of brine is to return it to the ocean, but high localized brine concentrations raise seawater salinity and alkalinity, creating an environmental risk. Read more›››

Another common way to dispose of brine is to use evaporation ponds, where the water is evaporated and the salt is collected for use in other processes. Unfortunately, neither method is a fully environmentally friendly approach, and untreated brine can be corrosive and toxic if disposed of improperly.

A collaborative work between King Abdullah University of Science and Technology, Saudi Arabia, and Khalifa University of Science and Technology, UAE, saw the design of a solar crystallizer that uses solar energy as the main energy source to heat and evaporate the brine. This follows the same concept as an evaporation pond, except the condensate from the evaporated brine is collected as fresh water.

This sounds like an obvious solution to reducing the water loss, but the amount of salt in the water can affect the performance of the materials in the crystallizer, so the team needed to design a new device in which the water-evaporation surface and the light-absorption surface are separated by an aluminum sheet with high thermal conductivity. The bottom and inner walls absorb the solar energy, while the outer wall performs the evaporation and crystallization parts of the process.

The research team says the high thermal conductivity of the aluminum separator conducts the heat generated at the bottom of the device to the walls for water evaporation, resulting in a “high solar-to-vapor performance.” They believe this is a simple but promising strategy to provide a low-cost and sustainable solution for treating industrial brine, especially in small- to medium-size applications.‹‹‹ Read less

SEAWATER: SEE WATER

Desalination is an energy-hungry process. According to Richard Muller, professor of physics at the University of California, Berkeley, it will always take one kilowatt hour or more of energy to desalinate a cubic meter of seawater.

RELATED: Khalifa University is a hub for desalination research

But Corrado Sommariva, founder and CEO of the Middle-East-based Sustainable Water and Power Consultants, says the desalination sector has been experiencing a revolution in the past five years and believes the process can be powered by renewable energy, particularly solar.

The cost of desalination from reverse osmosis has fallen dramatically in recent years, with much of this decrease in price stemming from streamlining processes and cheaper electricity, he notes, and as solar power looks set to become the cheapest form of electricity, moving to a renewable-power supply seems inevitable.

Tom Pankratz, editor of the US Water Desalination Report, confirms: “Desalination is more energy-intensive than other water-treatment processes, so there’s a growing interest in using renewable energy to reduce a plant’s operating costs and its environmental footprint. In many places, especially in the Middle East where desalination is the primary source of water, renewable energy is often much less expensive – even with the abundance of fossil fuels in the region.

”In theory,” he says, “any form of renewable energy could power desalination, but solar power is generating the most attention. Helpfully, the arid regions that need desalination the most are also the ones blessed with abundant sunshine.

IMAGE: Anas Albounni, KUST Review

Solar stills:
A classic solution

Sometimes the old ways are the best ways. Read more›››

The oldest desalination technology is the solar still, a simple device that uses sunlight to purify water.

Salt water is placed in the still and an angled piece of glass or plastic is placed above. The sunshine evaporates the water, which then condenses on the surface above before running down the surface to collect in a separate trough.

The impurities and salt remain in the bottom of the still and the water in the trough is clean, pure drinking water.

If you do find yourself lost without a clean water supply, you can make a solar still from a sheet of plastic lining a hole in the ground, a mug to collect the clean water, and another plastic sheet on top anchored with a rock to create the angled surface.‹‹‹ Read less

“Solar farms are sprouting up in more and more areas in the Middle East, and their power generation gets priority to feed into the grid,” Sommariva says. “For at least six hours a day, power tariffs as low as 1 U.S. cent per kilowatt hour are available to utilities from photovoltaic plants as the amount of electricity being generated by these plants will shortly outstrip grid demand during certain hours of the day. Photovoltaic power offers the chance to both operate desalination plants as potable-water generators and grid-energy absorbers and buffers.”

A TOUGH BALANCE

The journey of electricity from the power plant to our homes and businesses is not always a smooth one. Grid operators are faced with the complex task of balancing the amount of electricity fed into the grid against the amount of electricity consumed to keep the power system stable. But as more intermittent renewable-energy sources of electricity, like solar and wind, are fed into the grid, this balancing act becomes even more challenging.

Pankratz notes that it’s no coincidence renewable-energy desalination plants are being implemented in Saudi Arabia and the UAE, where some of the largest solar photovoltaic power plants are also being built.

“For larger plants, it is often infeasible to locate a large wind- or solar-energy power plant near a coastal seawater desalination plant. In these cases, it is usually more practical and cost-effective to build the wind or power plant farther inland, and feed the energy into an electrical grid that can be distributed to the desalination plant and other facilities,” Pankratz says.

“This approach not only ensures that the desalination plant and energy plants are located where they are most cost-effective, but it also eliminates, or lessens, the need for large batteries to store the energy during the night or low-wind conditions.”

AN INGENIOUS BATTERY

Sommariva believes solar-power-driven desalination plants could also act as an electricity-storage system, using the excess electricity produced by photovoltaic plants, rather than continuously running fossil-fuel plants, to desalinate water. Connecting the desalination plant to the renewable-power grid could be the solution to two problems facing the region: renewable-energy storage and drinking-water shortage.

Additionally, producing water when excess power is available from solar power and curtailing production when the grid is in peak mode does not require any dramatic changes to infrastructure, except an increase in storage capacity for the resultant potable water. As Sommariva points out, additional water-storage capacity is part of the strategic development in the region anyway.

“If the industry could simply move away from the traditional concept of steady water generation mainly dictated by a lack of storage, we could imagine a desalination plant able to operate in a sustainable and flexible manner: producing when excess power is available in the grid from photovoltaic production and curtailing desalination when the grid is in peak mode,” Sommariva says. Additionally, producing water when excess power is available from solar power and curtailing production when the grid is in peak mode does not require any dramatic changes to infrastructure, except an increase in storage capacity for the resultant potable water. As Sommariva points out, additional water-storage capacity is part of the strategic development in the region anyway.

CAPTION: Solar power-driven desalination plants could also act as an electricity-storage system. IMAGE: Anas Albounni, KUST Review

“It is necessary that policy makers start seeing desalination not only as a water producer but also a potential energy buffer and indirect storage system,” he says, adding that all of the desalination plants in the Gulf region and worldwide have the opportunity to smart retrofit and develop a net-zero-energy operational process.

CONTINUED IMPROVEMENTS

The potential use of renewable energy for desalination is hardly a new idea. Reported since the mid-1990s, a few conventional water-treatment plants in the United States have integrated solar power for water treatment, including a Massachusetts plant in 2009.

IMAGE: Anas Albounni, KUST Review

Managing
the resources

Previous poor water management and unsustainable agriculture practices in the Middle East have exacerbated desertification, and water scarcity is becoming severe in countries including Jordan and Yemen. Read more›››

Agriculture, industry, urbanization and population growth are all fueling the demand for more water, while climate change decreases supply day by day.

As the UN Food and Agriculture Organization points out, for every 1 degree Celsius of global warming, 7 percent of the world could see 20 percent of renewable water resources dry up. More frequent and severe droughts, combined with crops needing more water in higher temperatures, will put further pressure on dwindling water supplies.

According to the Water Project, other concerns with the future of desalination plants in the Middle East focus on the improper dependency they will cause, instead of encouraging alternate forms of water and energy to be explored and conservation of fresh water.‹‹‹ Read less

New renewable-energy technologies are becoming available for desalination applications as well. For example, an Australian pilot project utilizing wave-power technology for seawater desalination using submerged buoys began operating in 2015.

Despite the challenges, many researchers are working to improve desalination so it can reach more people and address climate change without contributing to it. The Global Clean Water Desalination Alliance has set a goal for 20 percent of new desalination plants to be powered by renewables between 2020 and 2025. Currently, the global share of renewable energy used in desalination is just 1 percent.

Sommariva does point out that the main challenge in pivoting to renewable-energy-powered desalination is retiring or converting traditional thermal-desalination assets.

“These plants have a residual economic life of several decades,” he explains. “Not to mention they are substantially energy-intensive. But desalination is a technology that is fast developing.”

There haven’t been any major recent breakthroughs in the technology, he adds, but the process is seeing a steady rate of improvements that are fine-tuning the process for ever-increasing efficiency.

A GROWING APPROACH

Already, stakeholders in the desalination industry are beginning to turn to renewables.

Dubai Electricity and Water Authority is planning to power its desalination plants with solar power by 2030, pushing for increased efficiency and large-scale integration of renewable energy in its water-production processes.

CAPTION: The desalination triangle: When the oil runs out, can the sunlight step in to power the process? IMAGE: Anas Albounni, KUST Review

In Port August, Australia, one desalination plant uses solar power to provide potable water for its tomato farm. In fact, in Western Australia, all new desalination plants must use renewable energy.

“All of the large Australian seawater desalination plant operators have contracts with renewable energy providers who supply energy into the local grid in an amount equal to that required by the desalination plant, in a cost-offset arrangement,” Pankratz adds.

Both the King Abdullah Economic City and the King Abdulaziz City for Science and Technology in Saudi Arabia are supplied by solar-powered seawater desalination plants, taking water from the Red Sea. Also in the United Arab Emirates, one Masdar plant in Ghantoot produces desalinated water using a solar-powered solution. The company behind this plant, Mascara Renewable Water, is now developing similar projects in Mauritius, Cape Verde, South Africa, Morocco and Vanuatu.

OTHER PROJECTS

There have also been several small-scale trials across the Middle East, Spain and India bringing together concentrated solar power and seawater desalination. Pankratzs says there are on-going research projects looking into using other forms of renewable energy too, including those from wave power, geothermal and biomass sources, and even from the energy contained within salinity, chemical and pressure gradients.

“There is absolutely a real future for this, and it’s happening now,” he says. “Renewable-powered desalination is proving itself in plants in the GCC and around the world. It’s happening on a local scale too, with hundreds of small, renewable-energy desalination plants under construction in island communities and off-grid locations in developing countries such as Kenya, Madagascar, Mozambique and Nigeria.”

Desalination can provide sufficient quantities of water as and when needed, which can significantly enhance the water security of a nation, while also supporting regional stabilities by evading any conflict over water resources. This also means there are a plethora of opportunities for society to benefit from desalination technologies.

Local employment opportunities during the construction and operation of desalination plants are one such benefit, but easy access to cheap water also means more work and education opportunities for women, who otherwise typically bear the often expensive, time-consuming and physically taxing burden of collecting and carrying water in the poorest communities.