Given the generally arid and dry climate of the Middle East, it is no wonder that water scarcity continues to be a challenge, which the region’s governments grapple with; and one which researchers from the Swiss university ETH Zurich have come up with a zero-energy solution for.
While desalination of sea water through reverse osmosis is popular in the GCC, it is an “energy-intensive process at a time when the world is moving towards renewable energy sources and is concerned about damage to the environment”, said Iwan Hächler, doctoral researcher at ETH Zurich, a public research university in the Swiss city.
“At this point, only 0.5 percent of the water on earth is readily available for human consumption, while 40 percent of the world’s population is affected by water scarcity,” said Hächler.
“While desalination is an option to produce drinking water out of salty saline water, it requires a lot of energy and the impact of this is something to consider if we want to make that shift towards renewable energy,” he continued.
As such, researchers at ETH Zurich have developed a zero-energy condenser for countries where water is in short supply. Their solution harvests water from the atmosphere throughout a 24-hour daily cycle with no energy input, even when under the sun.
“We worked on a system that is completely energy neutral to produce drinking water without any energy or work. You just place it there, let it run and it gives you drinking water,” explained Hächler.
Iwan Hächler, doctoral researcher at ETH Zurich.
The device is made up of a specially coated glass pane, which both reflects solar radiation and radiates away its own heat through the atmosphere to the outer space. It therefore cools itself down to below the ambient temperature. On the pane’s underside, water vapour from the air condenses into water droplets, explained Hächler.
Because the maximum fresh water yield that can be achieved through the device is 1.4 liters per sqm per day, it is not designed to supply water for a whole city, but rather communities in remote area or as a zero-energy supplement to a main water source.
“It cannot compete yield-wise with desalination, but I think it is important to put things in perspective. The cost of desalination, which is basically reverse osmosis, is a lot of energy and while currently we have cheap energy so it is not an issue, you have to think of the future. Our solution has the advantage of being completely energy neutral,” explained Hächler.
Condensed water droplets on selective emitter.
Optimal conditions for the water harvester are a constant 64 percent humidity or higher and blue skies, both abundant factors in the Middle East in general, and the GCC specifically.
Hächler revealed he was contacted by an entity from Oman for the use of the water condenser in their goat farms while water consultants from Saudi Arabia’s Neom and the Red Sea Project have contacted him several times for “knowledge transfer and idea generation. It is preliminary at this stage”, said Hächler.
While the research team behind the device have not done a cost analysis yet, Hächler said the small prototype, which generates 1.2 liters of water per day, costs $20 to produce. The most expensive component is the reflective silver which could be replaced with a special type of white paint, explained Hächler.
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