New solar-powered system makes desalination ecofriendly

System achieves new level of efficiency in harnessing sunlight to make fresh potable water from seawater


A completely passive solar-powered desalination system developed by researchers at Massachusetts Institute of Technology (MIT) and in China could provide more than 1.5 gallons of fresh drinking water per hour for every square metre of solar collecting area. 

Such systems could potentially serve off-grid arid coastal areas to provide an efficient, low-cost water source, said MIT doctoral students in a paper appearing in the journal ‘Energy and Environmental Science’.

The key to the system’s efficiency lies in the way it uses each of the multiple stages to desalinate the water. At each stage, heat released by the previous stage is harnessed instead of wasted. In this way, the team’s demonstration device can achieve an overall efficiency of 385 percent in converting the energy of sunlight into the energy of water evaporation.

During a trial the device managed to generate 5.78 litres of pure water per square metre. This is more than twice the amount produced by other passive solar-powered desalination systems. 

The new solar-powered desalination device could be deployed in arid off-grid coastal areas to provide an efficient, low-cost water source.

With more desalination stages and further optimisation, the new passive solar system could reach efficiency levels of up to 800 percent, according to the researchers. 

The new system could prove vital for sun-drenched countries in the Middle East, such as Saudi Arabia, Kuwait and the United Arab Emirates, which produce well over half of brine on the planet.


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