Using wind to get water

Canberra Times
Monday 19/3/2007 Page: 6

A WIND-DRIVEN device could provide an unlimited water supply by harvesting water from the air, says its Australian inventor. But critics are asking if it's too good to be true. Dr Max Whisson, a retired medical specialist turned inventor, says he has designed a highly efficient wind turbine that can run a refrigeration system to cool air and condense moisture from it.

The wind carries in the water and [provides] the power required to separate that water from the wind," Whisson, who is based in Perth, says. He says there is a huge amount of water in the atmosphere that is replaced every few hours. This means the whole world could just use water from the air without disrupting the environment. Whisson says the system would even harvest significant amounts of water in areas with low humidity. He says a 4sqm device could extract an average 75001 of water a day.

In his design, moisture laden air enters the system and is cooled by a drop in pressure behind the wind turbine blades, says Whisson. The air then flows into a chamber containing refrigerated metal plates covered by a non-wettable surface that causes water droplets to run off immediately into a collection point. Full technical details of the design are not available but at least one mechanical engineer is sceptical.

"I have found in general that inventors tend to enormously overstate the capacities of their devices. They just have a very rosy outlook on what their devices will do," mechanical engineer Professor John Reizes, an adjunct professor at the University of New South Wales, says. "It's not until you've made one that you discover all the problems." Reizes, who specialises in heat transfer, says he is sceptical because of the huge amount of energy that is needed to condense water.

Whisson says he is well aware that a large amount of energy is required to do the job. "It's like boiling a kettle in reverse." But he is confident his wind turbine, still subject to patent applications and yet to be independently tested, is efficient enough. The wind turbine is a surprisingly good development. I'm surprised because it performs so well," Whisson says. And he says the power generating part of the wind turbine can simply be increased to collect the wind power required for the condensation process.

See www.abc.net.au/science