Tuesday, February 06, 2007

Whisson's windmill

Cheap, unlimited water extracted from thin air?

Was listening to the Phillip Adams' "Late Night Live" programme repeat this afternoon and heard an amazing interview with a character named Max Whisson. As always, while everybody is looking in one direction (recycle, de-sal, more dams), somebody thinks laterally and comes up with an elegant, simple solution to a very vexing problem. Rain not necessary.

Click the title for the podcast of the interview (or transcript if available). The following is an extract from an article previously written by Phillip in "The Australian".
Haven't really thought much about what I can say about all this, just wanted to get it into circulation. Apparently this guy has designed a super efficient turbine system that works on wind-power, draws air in and extracts the moisture within. If Whisson's Windmill works as well as they say it does .. well .. somebody is going to be a very, very rich man. My only hope is that they get the patents sorted. Far too many brilliant Aussie ideas and inventions have been pinched by the Y(w)anks and sold back to us at great expense.


Link said...

I did hear that and I also read in the Ostrayian a week or so ago. Sounds almost too good to be true, but it wouldn't surprise me at all if it worked. Haven't quite got an image of how high up the windmills need to be, probably wasn't paying attention, radio reception here is pretty crappy. Fingers crossed, the man IS a genius. The only troubling line is the oceans would immediately replace it. I guess the oceans are pretty big eh? Full of the stuff.

Davo said...

Radio reception?? just click the title .. listen now or download.

Apparently ya can sit one on the ground or top of the roof (though need a biggish roof). Wouldn't worry too much about the oceans drying up (just yet), they're merrily being filled by Arctic meltwater .. heh.

JahTeh said...

Something else was done in the Canary Islands, I think but they used plastic stretched between poles to catch the morning mist which then ran down the plastic into containers. New Scientist had the story but when I need it I can never find the right issue.

GreenSmile said...

If you are going to generate the massive ammounts of electricity it will take to run an AC unit that was big enough to distill enough water for a tiny garden by burning fuels in a generator, you'd better rescue the H2O that condenses from the exhaust while you are at it.

the economics of this sort of thing are just rediculous but the energetics of it are even worse.

We have to start thinking about closed systems.

GreenSmile said...

I am not sure anything I just commented made sense to a non physicist but let me try again:

The gas it would take to condense X liters of water out of the air in a normally dry climate would probably be enough to truck in 10 X liters from a remote source where surface water was more plentiful.

Davo said...

Apparently he's been getting a lot of flack, along the lines of what you just said Greensmile. There isn't enough tech. detail in the interview, or on his website (link on the RN page) for me to comment much. I did say "if" it works. One of the interesting things, though, is the design of the turbine, which apparently starts whizzing in the slightest of breezes, and is extraordinarily silent. Wider applications for that, at least.

Have also seen a very cheap, efficient, evaporative distillation system for treatment of effluent in remote areas - on the local ABC's "New Inventors", but will have to try to track that down.

There is also a system similar to what Jahteh mentioned, up in the Andes, where large areas of what is essentially "shade-cloth" is stretched across the path of the mist. The water just naturally condenses and trickles in an endless stream down to the villages.

There are plenty of ideas like these around, but once "big business" gets involved, most of these "odd" little ideas get shoved aside.

"Who killed the electric car?"

BBC said...

Ah, water, the next thing to fight over. Oil we can learn to live without, but not water.

You can bet that the capitalists are working all the angles as I speak. I've followed this for a few years now.

Whatever, I moved here after a dream. I have plenty of water, and no water bill. Not even a well. :-)

Davo said...

Am a little surprised, and disappointed, by those comments, Greensmile. Was under the impression that you had a rather more open mind, than one enclosed in an engineers iron-clad box :-).

It doesn't, actually, take very much energy at all to run a refrigerator. On the farm we had one that ran on kerosene, and one powered by a 12V car battery, on the Campervan. Freezer and all.

If his turbine can produce 12 volts, or not even necessarily that, why wouldn't it work?

GreenSmile said...

Davo, you and i agree on lots of things and if my mind were any more open, cats would crawl in bed down there, but the core of the argument is nothing more substantial than Philip Adams saying:

The secret of Max’s design is how his windmills, whirring away in the merest hint of a wind, cool the air as it passes by. Like many a great idea, it couldn’t be simpler – or more obvious. But nobody thought of it before.

Nothing at all obvious here.
Something entirely missing from this article is going to have to do the convincing. The only other thing I have to go on is 4 years of physics taken long ago. Efficient turbines with blades in free air can not do much more than slow the air mass ever so slightly and set a bit of turbulence in theri wake. The cooling in a moving air colum traveling in a captive way, in some sort of channel or tube will come about when the channel abruptly widens. It is an effect related to venturis..only extreme or extremely abrupt preasure drops can force water vapor to precipiate. An airfoil in free air can only achieve a stable form of this pressure drop as a wake vortex.
Here is a study of such vortices in water but wing tip vortexes such as seen at airports are similar and do become visible because of waterdroplets, a tiny fog, that form in the vacuum. But any structure imposed to capture the droplets would destroy the vortex and its vacuum. Forgive me old pal but I must remain skeptical. Simply put, the energy and the intensity of the wingtip vortex of a commercial jet requires enormous force to produce. Unless Whisson has found some different principle of physics, I don't see where a blade moved by the breezes is operating in a pressure drop regime that could extract water. High speed airflow over the blades without power being applied to the blades or some kind of wind concentrator seem unlikely. I will think about it a bit before I call Whisson's honesty or Mr. Adams' judgement in question. A conventional windmill driven well would have to net you more water even if water table was 300 meters under ground.

here is a quick and very rough analysis of a more conventional way to distill water from the air...and because is it realisable with equipment of known performance, it sets a bound on what claims are even possible.

one gallon of gas releases 114100 BTUs when burnt.
The most optimistic numbers for comustion engine efficiency are well below 50%
Many pages of info on EER and COP but this page puts together all the realistic options for
heatpumps. the upper [yellow] graphs apply whre you have a ground water heatsink for the
heatpump Since the question here is how to use a heat pump to get water where none is otherwise
to be had, use the lower[green] curves and geneously take the very lowest temp-difference end of
the chart....get COP of 8. ie you put in one BTU of applied energy, you get to remove 8 BTUs from
whatever you are cooling.

So, one gallon of gas in an engine that drives the compressor of a heat pump will be able
in really ideal circumstances to remove 50% X 114100 X 8 = 456400 BTUs from your damp air.
Suppose you can chill the air enough to condense water but not have a net change of temp
for the air, ie you get your water with out refrigerating the great outdoors. THIS IS A
VERY GENEROUS stipulation and not entirely achievable but just to set an absolute upper bound
on the water you could obtain. One gram of water as vapor must give up 600 calories of latent
heat in order to condense that is 2.382557974 BTUs per gram or cc of water. i.e 2382.6 BTUs
per liter to get water from the air under the most wildly optimal and optimistics conditions.
our gallon of gas will gain us 191.6 liters of water from the air. And it would be free of minerals
for the most part which is more than can be said for water from deep wells in arid places.
A gallon of diesel has a bit more umph than the same volume of gas but no truck now
running gets that wonder 50% fuel efficeincy, a 10000 liter tank truck, loaded, won't do better than
say 2km/ltr...I am just guessing here, please offer a real number if you know it... if trucking
the water from a remote source were to compete with condensing water out of the air, fetching your
10000 liters of water must consume no more than 52 liters of petrol. Under my assumptions of
truck fuel milage, you can be 104km from a water source and still break even.
I leave it as an exercise to the student to compute the energy [MxGxh] needed to drag the water up from a well.

BBC said...

I have a 55 watt solar panel. It's cool. I just wish the prices would go down.

dr.alistair said...

yeah, sometimes the numbers get too much for people.

in the rain forsests water is so heavy inthe air that it condenses freely on your skin in seconds.

out in the desert the humidity is next to zero, so the energy demands of a system to draw what little water there is available into condensation would be large.

it is important to look for innovation but the science has to be right.

Davo said...

Am not a scientist nor engineer, so can't argue the technicalities; or whether it actually works or not. It does, however remind me a bit of Leonardo da Vinci who came up with ideas and designs for machines that were thought to be impossible at the time, the helicopter and "hooka" diving gear among others, which we now take for granted.

Can't really comment on the saturation of desert air, either, but the southern coast of Australia has a very long, flat, coastline facing the southern ocean. Have always wondered what happens to the moisture carried in by the prevailing South westerlies.

Be interesting if we could construct a "virtual" mountain range along there.