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In the most literal sense, a new ‘fog harp’ is able to generate potable water out of thin air, three times more than other designs.
As the effects of climate change take further hold on our planet, our water supply is expected to drop sharply in the decades to come, with some estimates predicting that nations such as India will experience a 40pc water deficit by 2030.
Nowhere has this crisis been more apparent than in the South African city of Cape Town where citizens are terrified about talk of ‘Day Zero’ – the day the water taps are expected to run dry some time in the months ahead.
This has led researchers to turn to drastic methods of water collection, including installing giant fog nets along hillsides and mountaintops to catch water out of thin air.
While it sounds more like an act of desperation, there is proven science behind it. Now, a team of researchers from Virginia Tech in the US has unveiled a new design that offers greater hope for the future by improving their yield threefold.
The basic concept allows for wind to move fog’s microscopic droplets through the nets. The droplets then get caught on the wires, gather in large amounts and drop to a collection point.
The problem is that if the holes in the mesh are too large, water droplets pass through without catching on the net’s wires. If the mesh is too fine, the nets catch more water, but the droplets clog up the mesh without running down into the trough, and wind no longer moves through the nets.
Study co-author Josh Tulkoff constructs a large prototype of the fog harp, which consists of a vertical array of 700 wires. Image: Virginia Tech
The special ingredient
In a paper published to ACS Applied Materials & Interfaces, the team’s research demonstrates how a vertical array of parallel wires may bring substantial benefits to fog harvesters.
Calling it the ‘fog harp’, the team said that these vertical wires shed tiny water droplets faster and more efficiently than the traditional mesh netting used in fog nets.
The team’s solution sounds rather simple as the researchers decided to just remove the horizontal wires to relieve some of the clogging. With some model testing, a working fog harp prototype was created.
Consisting of a vertical array of 700 wires that measure one metre by one metre, the design allows for greater amounts of water to be collected, but without the clogging.
“From a design point of view, I’ve always found it somewhat magical that you can essentially use something that looks like screen door mesh to translate fog into drinking water,” said Brook Kennedy, one of the study’s co-authors. “But these parallel wire arrays are really the fog harp’s special ingredient.”
