Million people around the world currently lack easy access to clean water and electricity at the flick of a switch. Perhaps even more importantly, there’s the Catch-22 relationship between clean water and electricity.
Fields of solar panels can bring electricity to populations in remote, dry places. But hosing them down with water is a good way to keep them clear of dust, which is not easily done in such arid locations.
Researchers realized they could solve both problems by creating a photovoltaic cell that uses sunlight as both a means to generate electricity and distil water. A compact device that uses waste heat shed by solar cells to purify water
A US-based start-up called Zero Mass Water uses solar energy to condense liquid water absorbed straight out of atmosphere, for instance.
The engineers of this latest device designed their cell with efficiency in mind, folding the components for distillation under a fairly standard silicon photovoltaic cell in a way that doesn’t impact on the cell’s energy output.
Just over 10 percent of the sunlight collected by their photovoltaic cell on a clear day goes towards generating an electrical current, an efficiency that isn’t too far behind conventional solar technology.
That heat is instead absorbed by a pancake-like stack of hydrophobic membranes shuffled between materials selected to assist evaporation and condensation.
By stacking the membranes this way, the researchers found they could improve on conventional solar stills, potentially producing about five times the amount of clean water.
Just a single square metre of this multi-stage membrane distillation device was shown to distil more than 1.6 litres of seawater per hour, all without compromising the amount of electricity being produced by the photovoltaic cell on top.
The next step for the research team is to investigate ways to push the boundaries on the device’s efficiency and affordability.
The interdependence between energy and water wages a heavy price on technologies that can potentially solve the problems of communities in need.