Great emphasis on the lo-tech easily maintained and repaired solution.

Unlike this popularized concept: http://starwars.wikia.com/wiki/GX-8_water_vaporator

There have been other products, including some on the market for using solar power to run refrigeration systems to condense water from air. The two factors of efficiency--amount of water produced--vs. price and simplicity of maintenance mean there could be several niches for water harvesters depending on the economy and investment climate of the community in question.

I hope this method is as promising as he feels it is. It is worth bearing in mind that when a new and improved solar cell is developed, it should not only be judged on whether it will be economical for solar cell farms attached to the grid but also on whether it can provide more power at less cost to off-grid systems and devices like these.

It would also be usful to pair this with a subsurface moisture barrier beneath the irrigation since deserts often lose more water downwards that through evaporation.

I can see this working in hot humid conditions assuming the ground temperature doesn't rise too high but what about hot dry conditions?

It would only work until the surrounding soil heated up, and the vapour ceased to condense.

Places like the New York and London underground railways were originally cool, but they have become hot and sweltering as the years pass, as energy is pumped in from bodies and trains.

http://www.thisislondon.co.uk/news/article-19451133-tube-is-hotter-than-miami.do

I imagine the efficiency of the Airdrop would quickly fall with use.

What an excellent idea! This reminds me of the water harvesters in Star Wars that the young Luke Skywalker had to tend for his family.

This has been done already a long time ago by uncle Owen and Aunt Beru in a galaxy far far way.

How much copper or aluminum will be needed per acre for the heat exchangers?

Am I the only one that sees that removing water from the air increases the area of the rain shadow.

lets just hope he changes from copper...because thats one expensive solution with coppers prices. theres a reason why wires are stolen from railway lines....

this is brilliant and low tech. I want one for the back yard.

This is brilliant but could I suggest constructing the reservoir so it is the same diameter as the rest of the tube?

Then the whole tube could be simply lowered into a hole dug by a post hole auger instead of the present design that requires a much larger diameter 2 meter deep hole

Would this work on Mars?

Calcium Chloride has been used for centuries to pull water out of the air. It facilitates extraction at low relative humidity. There is a known relationship between RH, temperature, and the rate at which CaCl2 pulls water out of the air. CaCl2 can be used to extract water in desert areas, and solar energy can be used to distill the water from the CaCl2, which will absorb more water the next cycle. Using temperature fluctuations in the desert (midday to near dawn), approximately 1 liter per sq meter of insolation is readily achievable.

I'd like to see a hybrid system using the referenced design and CaCl2.

This will be a great idea, as long as people don't have to make the trip to Toshi Station for replacement parts. ;)

seems to me that as long as the plastics are food safe this could be used to produce water for drinking as well. could you construct a giant one capable of servicing a family or even a village? for areas where a conventional well isn't possible.

This is a very good idea ,that is only if you are in the right climate zone for it to work.

What happens to the device when it is in a climate that freezes either seasonally or even at night ?

Would it still work?

In winter time once the frost is in the ground ,I would think that it would just freeze up and stop working unless the device is planted much deeper below the frost level.

In winter time the air is also much drier and therefore less moisture to be had until the relative humidity comes up and the temperature gets above freezing.

What about dry arid places like deserts ?

The moisture content of the air in arid places is even less than in the frozen winter time of other climates.

I suppose that if it ran long enough and the ground temperature was cool enough at ???? depth then it could extract water.

What about pairing the solar power panel with a rechargeable battery within the unit ??

It could run through the night in arid climates when the ambient air temperature drops and the relative humidity typically goes up so it would work faster and collect more without the competition of the sun's heat.

Will serve in emergency situations.

Paul Harrison-

I also wonder if a device like this or others (www.airwater.com.au) could work on Mars. I know that it has an atmosphere to make the idea possible, but as also posted above, what happens to these devices if it freezes?

In 1966, D.S. Halacy, Jr. wrote a book entitled "The Water Crisis". In the fifth century before Christ, the ancient city of Theodosia precipitated an estimated 800,000 gallons of water per day, using a number of "aerial wells"--about 80 feet by 100 feet, and about 30 feet high. The cross-section was pyramid shaped, made of rocks. The sides were covered with soil and sod to keep the rocks cool during the day. The ends were open and oriented away from the sun. At night, moisture-laden air circulated through the pyramids, condensing water.

Better use can be made of irrigation water these days by underground watering--watering plant roots only, a system I invented in the 1960s.

Origo1