A specially designed solar panel placed in contaminated water sources could efficiently use sunlight to create drinking water.
Researchers funded by the US Army believe they have found a way to create an inexpensive device to not only provide clean drinking water to soldiers, but to address the global water crisis in developing nations. Writing in Nature Sustainability, the University of Rochester researchers said their breakthrough is based on laser processing technology that turns regular aluminium pitch black.
This makes it highly absorptive and super-wicking, meaning it can carry water uphill against gravity. It can then be applied towards solar water purification using an aluminium solar panel.
When the solar panel is dipped in water at an angle facing the sun, it draws a thin film of water upwards over the metal’s surface. At the same time, the blackened surface retains almost 100pc of the energy it absorbs from the sun to quickly heat the water. Furthermore, the wicking surface structures change the inter-molecular bonds of the water, increasing the efficiency of the evaporation process even further.
‘Inexpensive way to address global water crisis’
“These three things together enable the technology to operate better than an ideal device at 100pc efficiency,” said Prof Chunlei Guo. “This is a simple, durable, inexpensive way to address the global water crisis, especially in developing nations.”
Lab testing showed the device could reduce the presence of common contaminants such as urine, heavy metals and dyes to safe levels for drinking.
The researchers said that until now, the most common method of solar-based water evaporation is volume heating. This heats large volumes of water, which only evaporates the top layer. Instead, this latest solar panel innovation pulls a thin layer of water out of a reservoir and directly onto the solar absorber surface for heating and evaporation.
“Moreover, because we use an open-grooved surface, it is very easy to clean by simply spraying it,” Chunlei said.
“The biggest advantage is that the angle of the panels can be continuously adjusted to directly face the sun as it rises and then moves across the sky before setting – maximising energy absorption.”