A cheap, energy-efficient desalination plant developed
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Three thousand years ago, King Solomon met the Queen of Sheba and told her that ‘nothing on Earth is more precious than water’. Today, with the world population continuing to increase, and with it our insatiable demand for freshwater, those words ring truer than ever. But, could a newly developed desalination system producing freshwater that’s cheaper than tap water mean that Solomon was wrong?
Only a little over half a per cent of the world’s water is fresh, liquid water. All of the rest is either salty or locked away in glaciers and ice. And, according to a report released in August 2023 by the World Resources Institute (WRI), the growing world population and rising world temperatures will lead to strain on the world’s freshwater supplies by 2050.
Many countries – particularly in arid regions such as the Middle East and North Africa – already rely on desalination plants in order to produce enough fresh water for their citizens. But, using current technology, turning sea water into drinkable water is an expensive and energy-intensive process. But that could be about to change.
Working alongside a Chinese team, engineers from the Massachusetts Institute of Technology (MIT) have announced in the journal Joule, the development of a new solar-powered desalination system that takes in seawater and, through heating it with natural sunlight, turns it into clean drinking water.
The system, which requires no electricity to function, works by allowing salty water to circulate in eddies and this circulation, combined with heat from the sun, causes the water to evaporate leaving the salt behind. The resulting water vapour is then condensed and collected as clean, drinkable water. Meanwhile, rather than accumulating in and clogging the desalination device, the leftover salt continues to circulate through and then out of the device. The result, according to the developers, is a desalination system with a higher water-production rate and salt-rejection rate than other passive desalination systems.
The team behind the project believe that if the system were scaled up to the size of a small suitcase, it could produce 4-6 litres of drinking water per hour and last several years. And, according to research scientist at MIT’s Device Research laboratory, Lenan Zhang, this new device can produce water that could be ‘cheaper than tap water’ in the United States.
While the team readily admit that their technology won’t be quickly supplying all the water needs of entire nations, they do believe that by producing scaled-up versions they could produce enough drinking water to meet the daily requirements of a small family. The system could also be used to supply off-grid, coastal communities where seawater is easily at hand.
And that alone could be a game changer because, as we all know, nothing on Earth is more precious than water.
