Global warming causes water shortages through droughts and disappearing glaciers. It also causes polluted water sources when there are floods, such as in the aftermath of Hurricane Katrina in New Orleans.

Indeed several reports on the impacts of global warming suggest the possibility of wars between nations over water.

So there is a great and growing need to alleviate water shortages and for clean drinking water.

There are several approaches to harvesting humidity in the air around us. Of course the first is to minimise the effects of global warming through going to the causes. Reducing greenhouse gas emissions, and to "reduce, re-use and recycle" are primary strategies.

Next, there are various technologies that can help. These include

*Desalination through distillation

*Condensation

*Water absorption by salt

Desalination is now widely used but water from air technology is the next trend.

Condensation

Dr Max Whisson has been called the Water And Wind Wizard of Oz. He has patented the "Whisson Windmill", or "Water Harvester", as he prefers to call it. It harvests water from air.

How?

Well, Dr Whisson was inspired by a little African beetle which collects the early morning's condensed water from its own body. From that observation he developed his windmill that produces water from air.

As Dr Whisson has put it: "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."

The water you see collecting on the ground under your car's airconditioner is an example of the same condensation process that Whisson uses.

The Whisson windmill is essentially a wind turbine which is connected to a refrigeration compressor. A refrigerant cools the blades of the wind turbine, after which it is returned to a compressor. The "free" energy from wind drives the cooled blades of the turbine and water is then condensed from the ambient air. This water is then collected.

This remarkable invention is under development with the University of Western Australia.

Similar to Whisson's Windmill water from air principle the Air Water Pty Ltd's Air Water Machines also harvest water from air by using a condensation method. Its units are on the market now, with capacities ranging from 28 litres (7 gallons) per day to 5000 litres per day (1321 gallons).

Water absorption by salt

This approach harvests water from air by forcing air through a liquid lithium chloride salt solution. This compound attracts water from the air, after which it is extracted and filtered through table salt which acts as a natural disinfectant. The final step is to filter this water through a carbon filter, adding taste.

These units can make up to 1200 gallons of drinking water per day and have been purchased by The US FESA for emergency relief purposes.

Water from air ? The Holy Grail?

So you see there are some pretty interesting developments under way that promise clean water. But are these alone the answer to a sustainable future?

We cannot use technology to refreeze disappearing glaciers or the ice caps, refill rivers, remake their entire ecology or stop rising oceans due to global warming.

More than technology is needed for that ? useful as it is. A truly sustainable future will involve love of our home, the Earth, and for each other. Simple as that.