Solar device makes 20L drinking water a day from seawater with 93% efficiency

Researchers at the University of Waterloo have developed an energy-efficient desalination device that uses the sun’s power to produce clean drinking water from seawater.

This innovative approach could provide a sustainable solution to the global water crisis, especially for coastal and island nations where fresh water is scarce.

The new technology, which mimics nature’s water cycle, could revolutionize desalination by offering a cost-effective and eco-friendly alternative to traditional methods.

Tackling global water scarcity with solar energy

The need for fresh water is more urgent than ever, with approximately 2.2 billion people worldwide lacking access to clean drinking water. Rapid population growth and increasing water consumption are adding to the pressure on coastal and island nations, where desalination has become a vital process.

According to the UN World Water Development Report 2024 , the demand for new technologies that can efficiently generate fresh water has never been higher.

Traditional desalination systems, which rely on pushing seawater through membranes to separate salt, are energy-intensive and prone to operational issues. Salt buildup on the device’s surface often clogs the system, requiring frequent maintenance and disrupting continuous operation.

Researchers at the University of Waterloo, however, have found an innovative solution. Inspired by nature, they developed a solar-powered desalination device that mimics the way trees naturally transport water from their roots to their leaves.

“Our inspiration comes from observing how nature sustains itself and the way water evaporates and condenses in the environment,” explains Dr Michael Tam, a professor in Waterloo’s Department of Chemical Engineering.

The new device efficiently evaporates and condenses water in a closed system, eliminating salt buildup and significantly improving the process’s sustainability. Unlike traditional systems that need constant cleaning, this new technology ensures continuous desalination without interruptions.

Solar power: The key to energy efficiency

What makes the Waterloo device particularly impressive is its reliance on solar energy. Utilizing advanced materials, the system can convert 93 percent of sunlight into usable energy, a significant improvement over current desalination technologies.

This high efficiency allows the device to produce around 20 liters of fresh water per square meter every day, meeting the World Health Organization’s recommended daily water requirement per person.

At the heart of the system is a combination of innovative materials. PhD students Eva Wang and Weinan Zhao, who are part of the research team, designed the device using nickel foam coated with a conductive polymer and thermoresponsive pollen particles.

These materials absorb sunlight across the solar spectrum, converting it into heat. A thin layer of seawater on the surface of the polymer heats up and moves upward, similar to the capillary action found in trees.

As the water evaporates, the salt is carried down to the bottom layer of the device, effectively preventing blockages. This self-cleaning mechanism is reminiscent of a swimming pool’s backwash system, allowing the device to run continuously without maintenance.

“The system we’ve engineered induces water to evaporate, transports it to the surface, and condenses it in a closed cycle, effectively preventing the accumulation of salt that reduces the efficiency of the device,” Dr Tam elaborates in the press release.

Portable solution for remote areas

In addition to its energy efficiency, the device is also portable, making it an ideal solution for regions where fresh water is scarce. “This new device is not only efficient but also portable, making it ideal for use in remote regions where access to fresh water is limited,” says Dr Yuning Li, another professor from Waterloo’s Department of Chemical Engineering, in the press release.

Li contributed to the development by generating solar energy for the project and testing the device’s light-harvesting capabilities using a solar tester.

The device’s portability and ability to operate in remote locations make it an attractive option for coastal communities, where desalination is often a necessity. The researchers believe their system could be a game-changer for areas with limited infrastructure and resources to access fresh water.

In the future, they plan to build a larger prototype to test the technology at sea and evaluate its potential for scaling up. “If the test is proven successful, the technology can sustainably supply fresh water to coastal communities and advance UN Sustainable Development goals three, six, 10, and 12,” adds Dr Tam, in the press release.

The study’s findings were recently published in Nature Communications .