Water from the wind

Water shortages and hosepipe bans have been in the news recently and even those of us who live in the wetter parts of the UK were asked to conserve water to avoid environmental droughts.

Of course, the problem is much more acute in other parts of the world, so as well as saving water we should also think about new ways of collecting it.

One possible solution is inspired by the behaviour of a beetle found in the Namib desert in Africa. The Namib is a coastal desert with some of the world’s largest sand dunes. At dawn the stenocara beetles, Stenocara gracilipes, climb the dunes and bow their heads toward the sea. Tiny droplets of water collect between the hydrophilic ridges and hydrophobic furrows on their wing casings and trickle down into their mouths. This vital moisture condenses from the mist generated when the wind over the cold offshore Benguela current meets the warming desert air.

Max Whisson, an Australian physician, has designed a device to capture this potentially huge source of water vapour that is carried in the air even when there is insufficient to fall as rain. The Whisson Windmill employs vertical columns of aero-dynamically-shaped blades rather than the conventional propeller-like blades of a wind turbine. These will turn in the slightest breeze from any direction and the spinning blades are cooled by a refrigerant which causes the water vapour to condense.

Whisson claims that his windmill could, potentially, collect hundreds of litres of water daily and would do so exclusively on wind power, since even the condenser used to cool the refrigerant runs off the power generated by the blades. His critics say this is “an elegant, simple but tricky idea” and reckon his estimate is too high.

The system certainly needs further development but even a few litres of wind-generated water could be life-saving to people who have little clean water available from other sources.