How to Turn Sea Water Into Fresh Water Without Pollution

In January 2021, Saudi Crown Prince Mohammed Bin Salman released a video announcing bold plans for the future. It was a keynote that seemed all too familiar, much like the late Steve Jobs announcing a new era of smartphones. However, instead of big tech, it's about futuristic urban development and utopian nation-building. The plans are ambitious. A linear city of 170 kilometers without roads, without cars and without

pollution

. This so-called revolution of civilization will house more than a million people. But there is an important point that was not addressed in the speech. A city this size needs

water

, a lot of it.

And we are talking about one of the driest places on earth. Water scarcity is omnipresent in the Middle East. In fact, while a global

water

crisis looms over many countries, it is affecting this region more than most. Exponential population increases and environmental impacts have led to the complicated situation of increasing demand for an increasingly scarce resource. To mitigate the problematic consequences, countries in the region have predominantly

turn

ed to an expensive and highly controversial measure: desalination. The principle of the artificial desalination process is simple. Water is extracted from the ocean, separated from its salt, and

fresh

water is delivered where it is needed, primarily for human consumption or irrigation.

Until now, there have been two main ways of doing this: Thermal desalination is the more traditional method which involves heating salt water and then cooling the steam to produce

fresh

water. The other technology, more sophisticated and dominant on the market, is called reverse osmosis. Using high pressure, salt water is pushed through a semi-permeable membrane to separate the salt. Reverse osmosis membrane systems typically use less energy than thermal desalination. However, both methods still have an enormous cost, both economically and environmentally. The economic costs arise from the high energy demands of desalination, which in

turn

were linked to an overall environmental cost, which depended on how the energy was produced.

In the Middle East, this mainly refers to fossil fuels. Desalination plants are responsible for a combined production of 76 million tons of CO2 per year. A figure that is expected to be almost three times higher by 2040. On a local scale, the main problem is the byproduct of desalination: hypersaline brine. After extracting fresh water, the brain is usually pumped back to the ocean. Because it is much denser than seawater, it sinks to the bottom, where it can harm ecosystems by increasing salt content and causing oxygen levels to plummet. All of this means that countries traditionally only turn to desalination if there are simply no alternatives available or if they need to become independent of a regionally disputed water source.

Egypt, for example, is betting heavily on expanding its desalination industry due to rapid population growth and growing fears of Nile droughts. Desalination is intended to ease tensions with Ethiopia upstream over the massive GERD dam project and fill the existing void. Across the border in Israel, drought and over-pumping have driven the biblical Sea of ​​Galilee to an extremely low level. The Inland Sea is Israel's largest reserve of fresh water, and its low level is now depriving the Jordan River and the Dead Sea downstream. Prime Minister Benjamin Netanyahu's government sees the solution in desalination. The intention is to pump desalinated water from the Mediterranean to the Sea of ​​Galilee and simply refill it.

Desalination is booming. The number of seawater desalination plants in operation around the world has more than doubled since the early 2000s. Today, more than 300 million people around the world obtain water thanks to this technology. A total of 173 countries have desalination plants, but the leader of the pack is undoubtedly Saudi Arabia, by far the largest of the few countries in the world without a single river. Its coasts are densely populated with desalination plants. Together, they produce more fresh water than any nation. A fifth of the world total. In Al Jubail, the world's largest desalination plant produces more than 1.4 million cubic meters of water per day and supplies fresh water to the country's capital.

With very little fresh water at its disposal, but awash in oil money, Saudi Arabia uses fossil fuels to generate the vast amount of electricity needed. The country also has to deal with huge amounts of waste from this energy-intensive industry. According to current standards of reverse osmosis technology, it takes two gallons of seawater to produce one gallon of fresh water. The remaining gallon is brine that is pumped back to the ocean. But all this is supposed to change. NEOM is Saudi Arabia's ambitious flagship gigaproject, a $500 billion investment in a country within a country located in the sparsely populated northwest along the shores of the Red Sea.

Among its key concepts are sustainability and environmental responsibility. But what is the substance behind these fancy slogans when it comes to meeting the huge demand for a scarce resource like fresh water in the desert? The solution should be an innovative technology that looks like this: a sphere made up of a glass and steel dome rising 25 meters into the air and covering a cauldron of approximately the same size. The so-called "solar dome" was developed by the UK-based company Solar Water in partnership with Cranfield University. The theory behind this is quite simple. Seawater is channeled through a glass-enclosed aqueduct system, which feeds the water with sunlight as it travels toward the dome.

A series of parabolic mirrors concentrates solar radiation on the dome. This superheated the seawater in the cauldron where it evaporated. As a result, highly pressurized steam is released and condensed into fresh water, which is then conveyed to reservoirs and irrigation canals. The solar dome should produce 30,000 cubic meters per hour at an extremely low cost of 34 cents per cubic meter. All 100 percent carbon neutral. But there is still the question of the hypersaline brain. The desalination process at NEOM supposedly reduces the total amount of brine created during water extraction, helping to prevent harm caused to marine life by not discharging brine into the sea.

However, until now, the question of what really happens to concentrated brine remains unanswered. Solar Water claims it can be extracted and sold commercially. The brine contains substances that can be used in other industrial processes. It remains to be seen if this actually works and if the plan to create commercially viable resource extraction for other industries will be successful. The first solar dome is currently being built to be tested on an industrial scale. The NEOM solar desalination project will serve as a test case for other water-scarce countries that are struggling to generate environmentally safe and sustainable freshwater sources.

Solar Water's vision is bold: carbon-neutral agriculture and reforestation in the middle of the desert. It is difficult to predict how much of this vision will prove true. NEOM will certainly put it to the test with the first solar dome desalination plant scheduled for completion in 2021. Desalination, for all its problems, is not going anywhere. As water becomes cheaper and scarcity becomes more and more threatening, the industry will continue to grow. And the countries of the Middle East will depend totally on it. It is up to all of us to manage the valuable resource of fresh water in a thrifty and sustainable way and it is up to science and innovation to find the most ecological and least harmful way to provide it.