UniSA creates floating sea farm to address water and food shortages

UniSA researchers have designed a self-sustaining solar-driven system that evaporates seawater and recycles it into freshwater.

In what is believed to be a world first, University of South Australia (UniSA) researchers have designed a self-sustaining solar-driven system that evaporates seawater and recycles it into freshwater, growing crops without any human involvement.

It could help address looming global shortages of freshwater and food in the decades ahead, with the world’s population expected to reach 10 billion by 2050.

Professor Haolan Xu and Dr Gary Owens from UniSA’s Future Industries Institute have developed the vertical sea farm, which can float in the ocean and produce fresh water for drinking and agriculture.

The floating sea farm is made up of two chambers: an upper layer like a glasshouse and a lower water harvest chamber.

“The system works much like a wicking bed that household gardeners might be familiar with,” Owen said.

“However, in this case, clean water is supplied by an array of solar evaporators that soak up the seawater, trap the salts in the evaporator body and, under the sun’s rays, release clean water vapour into the air.

“This vapour is then condensed on water belts and transferred to the upper plant growth chamber.”

The system, which is powered only by solar light, has several advantages over other solar sea farm designs currently being trialled, according to Xu.

“Other designs have installed evaporators inside the growth chamber which takes up valuable space that could otherwise be used for plant growth,” Xu said.

“In our design, the vertical distribution of evaporator and growth chambers decreases the device’s overall footprint, maximising the area for food production.

“It is fully automated, low cost, and extremely easy to operate, using only solar energy and seawater to produce clean water and grow crops.

“It is not inconceivable that, sometime in the future, you might see huge farm biodomes floating on the ocean, or multiple smaller devices deployed over a large sea area.”

UniSA researchers have also shown that the recycled water produced by the floating farm is pure enough to drink and has less salinity than indicated by World Health Guidelines for drinking water.

The United Nations estimates that by 2050, approximately 2.4 billion people are likely to experience water shortages and, in the same period, global supply of water for agricultural irrigation is expected to decline by around 19 per cent.

“Freshwater accounts for just 2.5 per cent of the world’s water and most of this is not accessible because it’s trapped in glaciers, ice caps or is deep underground,” Owens said.

“With 97.5 per cent of the world’s water is in our oceans – and freely available – it is an obvious solution to harness the sea and sun to address growing global shortages of water, food, and agricultural land.”

“Adopting this technology could improve the health and welfare of billions of people globally.”

The design experiment is published in the Chemical Engineering Journal.

UniSA supports industry capabilities and innovation through collaborative research projects with government and organisations.

Leverage UniSA research to enhance your own capabilities by connecting with the UniSA Enterprise Hub: unisa.edu.au/enterprisehub

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