Water from thin air

Scientists at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB have discovered a way of obtaining drinking water from air humidity.

Working alongside German company Logos Innovationen, the scientists have developed a system that uses a saline solution to absorb moisture from the air.

According to the team, this device could be useful in desert environments where there are significant quantities of water stored in the air.

Siegfried Egner, head of department at the IGB, explained: ‘The process we have developed is based exclusively on renewable energy sources such as thermal solar collectors and photovoltaic cells, which makes this method completely energy-autonomous.

‘It will therefore function in regions where there is no electrical infrastructure.’

The system works by running hygroscopic brine down a tower-shaped unit and absorbing water from the air.

It is then sucked into a tank a few metres off the ground, in which a vacuum prevails.

Energy from solar collectors heats up the brine, which is diluted by the water it has absorbed.

Because of the vacuum, the boiling point of the liquid is lower than it would be under normal atmospheric pressure.

The evaporated, non-saline water is condensed and runs down through a completely filled tube.

The gravity of this water column continuously produces the vacuum and so a vacuum pump is not needed.

The re-concentrated brine runs down the tower surface again to absorb moisture from the air.

‘The concept is suitable for various sizes of installation.

‘Single-person units and plants supplying water to entire hotels are conceivable,’ Egner added.

The scientists have already tested prototypes of the system in a laboratory environment and hope to develop a demonstration model in the near future.