The Rainmaker

New device uses alternative energy to pull water from the sky.

By Chris Ladd

Nearly all the water we humans use each day is up there in the atmosphere, some 3,100 cubic miles of it. Most of us are prepared to wait for that water to come down in the form of rain, snow, or other precipitation. Max Whisson, a retired Australian physician and inventor, is not that patient.

“The dependence of human beings on rain is the greatest evolutionary anachronism of all time,” Whisson says from his home in Perth. “We can fly to the moon and do all sorts of clever things, and we still have to wait for rain before we can water the crops or have a drink, and this seems absolutely absurd.”

But there is an easy way to get water out of the air: cool that air down. Think of the water that condenses on a cold glass, or drips from an air conditioner. Whisson’s idea was to recreate this effect on a larger scale.

Pulling water out of air could especially benefit people in the developing world who have limited access to fresh water, says Whisson. The U.N. estimates that some 1.1 billion people currently lack access to safe drinking water, a number which is expected to rise as the world's population edges closer to 9 billion by 2050.

“We have air everywhere to breathe, I don’t see why we shouldn’t have water everywhere to drink,” says Whisson.

And so, eight years ago, Whisson set out to solve the world's water problems, and settled on the device now known as the Max Water. The challenge was to engineer a device that cooled air quickly, without using any outside energy. In practice, this takes the form of a sort of mutant windmill. Wind blows through a set of turbines which then power a series of refrigerated plates. As the air passes over these plates, water condenses onto them and drips down into a collection tank, where it can be used for anything from drinking to irrigation. The plates, modeled on the lotus leaf, shed water quickly by forcing it to bead and roll, rather than drip and slide off, clearing the way for more water to condense on the cooled surface.

Completely off the grid, the prototypes of the device also make use of solar panels, which use very small amounts of energy to run the compressor and keep plates cool. Just how much water is collected depends on local conditions—hot air holds more moisture than cold, and windier weather will generate more water than calm conditions, moving more air over the plates and generating more electricity to cool them.

Still, Whisson is confident that a single unit will provide enough water for three or four households, extracting valuable water in even the driest of climates. “What we’re working towards is that a farm or community could buy or lease one of these devices and provide all the water they need,” Whisson says.

With the first large-scale test model recently erected at a farm near Whisson's lab in Perth, his claims are being put to the test. Depending on the results, he expects a final prototype to be available within six months at a cost of around $40,000. His company, Water UN Limited, also plans to donate a percentage of finished units to water-deprived areas in developing countries.

Anne Tihansky, a hydrologist with the US Geological Survey (USGS) in St. Petersburg, Florida, says scientists in her area are constantly looking for new ways to provide fresh water.

“All the traditional sources—groundwater, surface water, storm water—looking at all of those relationships for groups and balancing the needs of the ecology and human consumption, it’s all pretty much accounted for,” she says. “You can’t make water up. There’s only so much of it.” 

Though not familiar with Whisson’s Max Water, Tihansky says she’s seen wilder ideas floated at brainstorming sessions, for the simple reason that there’s just not enough water to meet the world’s demands. “I think that once people realize their supplies are limited, what seems like a crazy scheme will have much more relevance.”