Researchers desalinating greenhouse uses unexplained bubble physics

Researchers at Murdoch University, Australia, have designed a small-scale greenhouse that deploys desalination technology based on an “unexplained” bubble formation phenomenon to bring food production to remote regions with high-salinity groundwater.

The researchers claimed the so-called bubble greenhouse outstrips existing small-scale desalination technologies in its fresh water production capacity.

It uses a novel humidification-dehumidification process powered by solar or wind generation. A regenerative blower pushes air through sinter discs in a six-chamber column evaporator filled with saline water. This creates thousands of fine bubbles that saturate with water to be released in a multi-stage condenser to collect fresh water to humidify the greenhouse.

Research team member, Mario Schmack, said the large air/water interface created by the fine bubble column was enhanced by the use of saline rather than freshwater in the humidification step. He said saline water maintained the air/water interface by inhibiting coalescence of the bubbles by “a still unexplained property.”

The researchers said a 150 m² greenhouse could produce up to 30 kg of crops daily while generating fresh desalinated water overnight.

Schmack said simplicity was at the heart of the design, as desalination technologies such as reverse osmosis have proven untenable in remote areas due to their complicated nature.

“The bubble greenhouse system relies on basic technology such as regenerative blowers and technically undemanding water pumps, so it’s easy to implement and easy to maintain and repair by local people with limited technical means,” Schmack said.

The project was poised for scaling-up with industry partners.