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Chinese tech makes desalinating seawater cheaper than producing bottled water

Solar-powered innovation has exhibited year-long stability with zero utility energy costs, thanks to a new type of photothermal material

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Dannie Pengin BeijingPublished: 1:00pm, 29 Jun 2026

Desalination has always been an energy-hungry way of turning saltwater into freshwater, making it largely the preserve of wealthy countries with abundant fossil fuel reserves.

Yet, an outdoor demonstration prototype in China has managed to exhibit year-long stability with zero utility energy costs, thanks to a new type of photothermal material.

The researchers developed an innovative method to weave nanoparticles into a three-dimensional photothermal evaporation material, significantly boosting the efficiency of converting solar energy to drive desalination.

Experiments showed that the structure achieved a solar absorption rate of as much as 90.2 per cent, while cutting the energy needed to evaporate the same volume of seawater by 45.7 per cent.

At a small trial site, the device was successfully used for desalination, helping to irrigate five square metres (nearly 54 square feet) of farmland for a full growth cycle using only natural sunlight and requiring no external power grid infrastructure.

Based on a projected two years of operation, the team noted that the cost of producing water would fall below that of bottled water and that the economic advantage “would become even more pronounced if the system were scaled up or used over the long term”.

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