A new device has the potential to bring clean water and solar power to the more than 1 billion people around the world who live without electricity, and 844 million people living without access to safe water.
Researchers from King Abdullah University of Science and Technology in Thuwal, Saudi Arabia, shared an alternative to current water purification technologies on July 9, according to the Guardian. They found a strategy to use an integrated solar photovoltaic (PV) panel distillation device to produce fresh water and create electricity at the same time. Unlike similar technologies, their tool wouldn’t use up as much electricity or require infrastructure that communities living in poverty don’t always have access to, the team explained in the journal Nature Communications. But experts say technology alone cannot act as a silver bullet for the global water crisis.
The versatile device can be installed in dry regions, where clean water is needed the most –– 1 to 2 billion people are affected by water scarcity and most of them live in drylands. Or it can be used in backyards and adapted for larger areas. The researchers’ invention can generate clean water that can be used for cleaning solar panels to remove dust particles, according to Professor Peng Wang, co-author of the research. It also has the capability to irrigate plants and crops, and make desert agriculture possible, he said.
“It is an interesting application of the well-known designs of multi-stage evaporation and low-temperature heat recovery from PV panels,” Ashok Gadgil, faculty senior scientist at Lawrence Berkeley National Laboratory, told Global Citizen.
"The waste heat from PV panels has really been ignored, no one has thought about it as a resource." -KAUST lead author Prof Peng Wang. "We use the heat to generate water vapour that gets transported across the membrane then it condenses on the other side." https://t.co/asHaQQdkAL
— KAUST (@KAUST_News) July 10, 2019
While the researchers’ creation is not the first to make use of solar distillation, they say it has the advantage of being compact and combining two types of technology that usually require accessories and a large piece of land for use.
The device can be used to purify seawater contaminated with heavy metals at a higher rate than conventional solar methods to distill water. During testing in perfect weather conditions, the energy efficiency of the solar cell was about 11% according to the researchers, which is higher than previously reported by others working on similar devices.
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So how exactly does the device work? First, saline, brackish, or contaminated surface water is purified by running through silicon solar cells. Then "waste heat" from the solar cell warms the saline water passing beneath it, the water evaporates, passes through a layer, and condenses to deliver clean water. The heat that warms the saline water in the silicon solar cell below it is released as a result, and this process is then repeated for the next solar cell. Finally, the purified water flows out of the device and is collected.
Erik Harvey, WaterAid’s program support unit director, wonders what kind of invesment woud be necessary to use the device to ensure adequate water for human and other domestic uses.
"All technology requires good management," Harvey told Global Citizen, "which in turn requires a political, legislative and financial enabling environment, and this does not exist or is weak in many locations suffering from water stress."
The device's success rate is also contingent on whether there is enough water available in the first place, Harvey said.
Distribution and costs are another concern for both Harvey and Gadgil.
“The ultimate test of this new technology will be the price of desalinated water,” Gadgil said. “Is that water affordable for the population for which it is intended?”
The researcher team has outlined various versions of the device and is still working on scaling up the invention while reducing costs.