Whisson Windmill

The Whisson Windmill is a device that extracts clean drinking water from the atmosphere. It does this by drawing air in past a fan, whose blades are cooled by refrigerant. Because the blades are cooler than the air, water in the air condenses into a liquid, which is collected. It was invented by Max Whisson, a retired medical specialist who lives in Australia. Whisson’s invention was spurred by observations of the Stenocara gracilipes beetle of the Namib desert. This insect has a shell adapted to harvesting water from moisture-laden early morning fog. Smaller lumps on the shell are covered with a water repellent, wax-like substance. Larger protrusions are wax free and textured in a way that attracts condensation. To drink, the beetle rises from the sand at sunrise and essentially stands on its head with its carapace in the air. As the bead of moisture forms on its shell, it rolls down and into the insect’s mouth. Whisson claims his machine operates in a similar manner. To view a video illustrating how Whisson’s windmill is said to work, click here: http://www.youtube.com/watch?vGf0krn99Y20&featureplayer_embedded
Specifics as to the particulars of the Whisson Windmill are viewable in the filing made with the European Patent Office at: http://worldwide.espacenet.com/publicationDetails/biblio?CCWO&NR2006017888&KC&FTE&locale=en_EP
The Whisson Windmill has been cited as one possible method of dealing with climate change. Dr Whisson said of the device, "The essential principle is that more wind is used for power than for water supply. In other words, the area of power turbines is greater than the area of turbines leading to water harvest. This is all made much easier by the invention of a new kind of wind turbine or 'windmill'. The amount of water available in the air is for all forseeable practical purposes unlimited. The bottom 1 kilometre (in the atmosphere) alone contains about 1,000,000,000,000,000 litres of water and that is turned over every few hours. The 'Whisson Windmill' or Max Water From Air device will make it possible to get adequate water anywhere at any time, drought or no drought." He also stated, "A special feature may be that installation in drying lakes and wetlands would restore these threatened ecosystems." In addition, he said, "Isolated dry communities of course, where people must carry water in a pot on their heads to survive could be transformed, and our new little company is committed to providing some of the first units to such communities in need."
According to claims from Whisson, a device four meters square could deliver as much as 7500 liters of water per day. Much about the technical operation of Whisson’s device remains shrouded in mystery. Key details have been closely guarded as proprietary information until such time as the Australian patent process is complete and the windmill design has the protection of law.
Since its introduction to the public in 2007, there has been a dearth of new information regarding the Whisson windmill. Most substantive writings occurred between 2007 and 2009. Whisson was at that time seeking private capital to develop and produce his invention. Whether that lack of current news and information is indicative of failure of the concept, of the inventor’s desire to keep particulars about his device away from the eyes of competitors, or something else, is unknown. Other inventors and companies have fielded instruments to extract water from air to varying degrees of success.
Similar Devices
The Whisson windmill is hardly the only such device in existence that uses condensation as a means of generating potable water. Similar machines from other inventors have incorporated the same principle, and utilize some means of condensation capture to the same effect. These other mechanisms use a variety of means to power their work. Chief among them are electricity provided from a ground based grid, solar power, or diesel to run generators that power the devices. Whisson’s unique difference lies in his claim that wind alone is sufficient to power his windmill. In theory, that gives the Whisson invention portability that is unmatched by its commercial rivals. Few if any places on Earth are totally devoid of some degree of air circulation. If Whisson’s windmill is capable of operating even in low wind conditions, it would make it an ideal solution for bringing water to even the most remotely arid places on the planet.
Advantages
Chief among the advantages of Whisson’s approach to water harvesting is its ability to operate independent of other enabling power sources besides the wind itself. As discussed below, there are those who question the ability of Whisson’s windmill to do just that. Their doubts spring from a number of sources, not least among them is the physics of the energy required to do the task as Whisson describes it. What is hard to gainsay is the advantages of water extruded from the air around us. Unlike many existing units powered by diesel, the Whisson machine, as described, does not trade water for another environmental pollutant. Fumes from diesel generators contribute to air pollution and global warming. Devices powered by existing electrical grids are dependent on energy sources that create their own environmental tradeoffs. Solar power is clean, but require a means of storing power for those times when the sun is not readily available. Also, harnessing solar power in quantities sufficient to make significant contributions to the efficient operation of machinery is still a technology in its infancy. If Whisson’s windmill is able, as its inventor claims, to drive its turbines independent of any power source save that of the air’s own movement, it would signify a quantum leap forward in design. Plus, water generated from the air is generally pure of other contaminants associated with water extracted from ground sources or by techniques involving chlorine or even salts.
Criticisms
While other devices that generate water from air already exist, Whisson’s windmill is said to be totally eco-friendly, in that it requires only wind power to drive the refrigerant cooled, nano-engineered blades that cause condensation to form. That seems problematic for a number of critics, who find fault with the physics of Whisson’s device. Their criticisms attack the windmill on several levels:
• Some claim that the energy to generate the amount of water Whisson asserts it is possible to harvest on a daily basis is far in excess of what the inventor declares is needed. Critics with backgrounds in the physics of heat transfer note that current wind turbines are at best only 30% efficient. Complicating the equation even more is the fact that the energy driving them arrives from diffuse sources. Collecting that energy would likely require machinery far too large to be practical. Because of the expense involved in providing that energy, the Whisson windmill would not be cost effective, they say. One such naysayer offers the following equation to illustrate his doubts:
“Max says:
‘At 30 degrees centigrade, with a relative humidity of 60 percent, each cubic meter of air contains about 18 grams of water. If you can cool the air to 5 degrees, the air can only retain about 8 grams/cubic meter of water; the remaining 10 grams per cubic meter will condense as fog or droplets.’
We know:
Specific Heat (Air) = 1.01 kJ per kg per degree C
Mass (Air) = 1.2 kg per cubic metre
So;
To cool 1 cubic metre of air by 25 degrees, we need 1.0 kJ x 1.2 kg x 25 deg C
= 30 kJ
To get 10 mL of water...
To meet Max's modest estimate of 7000 litres per day, we need to collect 80 mL per second, or, cool 8 cubic metres of air by 25 degrees per second, so;
8 cubic metres x 30 kJ per second = 240 kiloWatts.
Unfortunately, the amount of kinetic energy in the same amount of wind is only about 0.1% of that...
KE = 1/2mv^2
mass 8 cubic metres x Mass (Air) 1.2 kg 9.6 kg
velocity^2 8 metres per second x 8 metres per second 64
So,
0.5 x 9.6 x 64 307.2 Watts 0.3 kW”
Others see a fundamental flaw in the math that shows how much water is in the air and available to be harvested by Whisson’s invention. Still other critics, using what they see as more realistic equations to compute the amount of water that can be generated in a single day by a single windmill unit, dispute the value of a system that generates less than a gallon of water per day per person for a village of 1,000 people. Yet another writer has noted that large-scale wind farms have impacted weather patterns in places where they are used by disrupting the atmosphere’s ability to form cloud masses that generate rain, and questions whether the Whisson windmill might have similar consequences.

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