Zurich – Researchers working at the Swiss Federal Institute of Technology in Zurich have developed a condenser for use in countries where water is scarce. It is the first zero-energy solution and moreover can also function 24 hours a day. The output it offers is close to the physical maximum.

Image credit: ETH Zürich/Iwan Hächler


A research team at the Swiss Federal Institute of Technology in Zurich (ETH) has developed a technology that could help countries suffering from a lack of water: a condenser that collects water from the ambient air. However, in contrast to the passive technologies already available, water harvesting is possible 24 hours a day, even under the blazing sun, ETH Zurich explains in a press release.

The new device features a cone-​shaped radiation shield connected to a horizontal glass pane at the bottom. Its special coating reflects both solar radiation as well as radiating away its own heat, meaning that the device is in effect self-cooling to as much as 15 degrees Celsius below the ambient temperature. On the underside of this glass pane, water vapor from the air is condensed into water.

As a general rule, other technologies of this ilk tend to require that condensed water is wiped away from a surface, ETH Zurich explains. This is an energy-dependent process. For this reason, the researchers applied a novel superhydrophobic (extremely water-​repellent) coating to the underside of the pane in their water condenser. As a result, up to 0.53 deciliters of water per square meter of pane surface is able to bead up and run off on its own accord on an hourly basis. “In contrast to other technologies, ours can really function without any additional energy, which is a key advantage”, explains Iwan Hächler, doctoral student from the Institute for Thermodynamics at ETH Zurich, in the press release. Moreover, the output is now “close to the theoretical maximum value of 0.6 deciliters per hour, which is physically impossible to exceed”, Hächler adds.

According to ETH Zurich, it is now conceivable that scaled-up versions of the pilot water condenser system installed on the roof of one of the university’s buildings could now be manufactured. Similarly to solar cells, several condensers could also be installed next to each other.

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