Given that the ocean covers 70% of our planet and accounts for 97% of available water, it’s a shame none is drinkable.
A new device developed by Dr Matthew Margeson at the Dasog Lab at Dalhousie University, Canada, could change that, offering access to clean drinking water in remote or developing areas.
The floating solar still can generate desalinated water and thermoelectricity, using materials as mundane as used car tyres.
Passive solar desalination
Once set up, the device is capable of desalinating water with a simple chemical process powered by the energy of the sun.
Sea water is wicked up from the ocean to the device’s foam surface, where solar-heated plasmonic materials evaporate the water, leaving salt behind as the now clean water condenses on a clear plastic dome before being funnelled to a sealed bag.
Desalination still design.
Refractory plasmonic materials refer to a type of material designed for high-temperature applications, resistant to wear and corrosion, that interact with light on a nanoscale.
“Refractory plasmonic nanomaterials are very good at capturing light and converting that light into heat,” says Dr Mita Dasog, an associate professor of chemistry and Killam Memorial chair whose research group explores potential applications of this technology.
Turning waste into energy
While plasmonic materials are generally expensive – gold and silver are the most commonly used examples – Dr Margerson’s device uses a much cheaper material created from carbon waste.
The waste is turned into pyrolytic char by being heated to high temperature in the absence of oxygen – a paper-thin layer of this char is coated over the desalination device’s surface, maximising heat and protecting it from the ocean water.
Dr Margerson and his team have tested coffee grounds, lobster shells and birch wood residue, with tyre rubber emerging as the best performer.
Tyres are a toxic nuisance that largely end up in landfill, taking hundreds of years to breakdown and decompose – turning them into pyrolytic char would offer a cheap way to reduce waste and produce clean water.
While the device is still being tested, the team intends to conduct a field experiment in South Asia, with the hope it can eventually be commercialised and used widely.
The team believes a portable, cheap water-producing device could offer a lifeline to communities displaced by war, climate change or lack of resources.
“Water is such a basic requirement for survival, so our hope is to be able to help communities like these,” Dr Dasog said.