Stan Meyer and the Water Powered Car

November 21, 2006 2:40 PM

Stan Meyer invented a water powered car that estimates showed could travel from one US coast to the other on 22 gallons of water. He shows the in car in operation in this old news clip. So what ever happened to him? He died after eating at a restaurant on March 21, 1998. An autopsy report showed the cause of death to be poisoning.
posted by banished (165 comments total)

So let me get this, it just "breaks down water into hydrogen and oxygen", then you use the hydrogen as a fuel, which makes water, which you could just break down again. And again and again, releasing more energy each time.

It's like taking regular motion, and making it go on forever. Why just waste it in beach buggies? We could use that elsewhere, making a boundless supply of endless energy and confounding those fuddy-duddy physicists and evil oil companies, if only Stan hadn't eaten a duff burger. And what more proof could you ask for than a dodgy local TV station buying the story?
posted by imperium at 2:48 PM on November 21, 2006

Couldn't help but notice that your Google Video link had a link back to davidicke.com - perchance, is that the same David Icke who believes the world is being controlled by a sinister cabal of reptilian humanoids?
posted by afx237vi at 2:48 PM on November 21, 2006

Your favorite perpetual motion machine sucks with no apparent energy source.
posted by CynicalKnight at 2:51 PM on November 21, 2006 [1 favorite]

The Google Video link is a clip from "It Runs on Water" narrated by Arthur C. Clarke. No surprise, you can watch the whole documentary on... you guessed it.
posted by banished at 2:52 PM on November 21, 2006

perchance, is that the same David Icke who believes the world is being controlled by a sinister cabal of reptilian humanoids?
posted by afx237vi

Yep, that's exactly the same David Icke.
posted by Reverend Robbie at 2:52 PM on November 21, 2006

needs the batshitinsane tag.
posted by b1tr0t at 2:53 PM on November 21, 2006

I love the idea of big lizards driving around everywhere in their water-powered vehicles.

But can we not talk about David Icke anymore, please? I'm a Green party member and he's still about as popular a topic with us as Mark Foley is with Republicans right now.
posted by imperium at 2:58 PM on November 21, 2006

How many times must we explain:

The damn car is not powered by water!

It is powered by a a BATT-ER-Y!!! SAY IT!! BAT-TE-RY!!! THATS RIGHT AN ELECTRICAL BATTERY THAT WAS CHARGED BY A SMOG SPEWING POWER PLANT!!!

The water is being decomposed into Hydrogen and Oxygen by a BATTERY! The gases are sparked, which causes an explosion, which makes car go forward, and water comes out exhaust pipe... and the whole process very INEFFICIENT!

GODDAMNIT, PEOPLE!!! STOP POSTING THIS WATER POWERED CAR BULLSHIT!

posted by StarForce5 at 3:02 PM on November 21, 2006 [2 favorites]

Two clarifications. David Icke has nothing to do with the production of the first clip. Also, the video notes that there is virtually no current consumed by the device, less than half an amp. Allegedly it is not a perpetual motion machine, but rather, a low-powered method of extracting hydrogen for use as fuel. I'm not adding these clarifications because I believe the device is real, but if you want to attack the post, at least do so on the merits.
posted by banished at 3:03 PM on November 21, 2006

Petrol cars aren't powered by petrol, they're powered by the sun shining on prehistoric foliage...
posted by Artw at 3:04 PM on November 21, 2006 [2 favorites]

Spoilsport. I shall pray in your resonant frequency and soothe your mind.
posted by CynicalKnight at 3:04 PM on November 21, 2006 [1 favorite]

a low-powered method of extracting hydrogen for use as fuel.

Take that laws of thermodynamics!
posted by Artw at 3:05 PM on November 21, 2006

The Google Video link is a clip from "It Runs on Water" narrated by Arthur C. Clarke.

So the info on the film clip, that it comes from BBC's science series Horizon, or from the side of the clip claiming it came from 60 Minutes are just plain old pork pies?

Of course, nobody in the clip besides Myers actually claims it works. Everyone else just talks about 'if'.

Me, I'd have taken the billion dollars from the arabs, but then, unlike Stan, I don't believe in the power of angels.

The power of giant lizards, on the other hand, is there for everyone to behold. Just look at our Royal Family, for example.
posted by PeterMcDermott at 3:06 PM on November 21, 2006

This reminds me, I heard of a case where a guy was suing the patent office because when they returned his model of a perpetual motion machine it was broken.
posted by exogenous at 3:07 PM on November 21, 2006 [1 favorite]

imperium writes "So let me get this, it just 'breaks down water into hydrogen and oxygen', then you use the hydrogen as a fuel, which makes water, which you could just break down again. And again and again, releasing more energy each time."

Yeah, I know. I wanna be all like, "Excuse me, sir. Allow me to introduce you to my friend, the Second Law of Thermodynamics..."



Seriously, though, I invented this water powered car when I was like 12. I remember it clearly. I was riding my bike home from soccer practice, I think, and I was thinking, "well, if you could have a car that burns hydrogen, and you'd make the hydrogen by electrolyzing water, and then the only waste would be water....I'll be a millionaire!" Then I took a high school chemistry class. Damn.
posted by mr_roboto at 3:09 PM on November 21, 2006

David Icke has nothing to do with the production of the first clip.

Perhaps not, but the fact that it's one of his supporters posting it to the net automatically sets off the 'batshitinsane' tag in our heads.
posted by PeterMcDermott at 3:09 PM on November 21, 2006

I'd love to see that autopsy report. It probably says food poisoning.
posted by dhartung at 3:10 PM on November 21, 2006

ugh!

its. its. its.
posted by PeterMcDermott at 3:11 PM on November 21, 2006

He was probably killed by his investors.
posted by stbalbach at 3:11 PM on November 21, 2006

I was not familiar with this Icke guy, but he may have the best wikipedia entry section titles ever:

Early life
Contact with the spirit world
Conspiracy writings
Reptilian humanoids
Alleged relationship with the far right
Allegations of anti-Semitism
Protests in Canada

Someone should do a version of wikipedia that is just the section headings.
posted by snofoam at 3:12 PM on November 21, 2006 [2 favorites]

Fave fact: apparently the Patent Office classify perpetual motion machines according to which law of thermodynamics they break. Normally the first, of course.
posted by imperium at 3:13 PM on November 21, 2006

Perhaps the FPP should have also said something about the fact that he was convicted of defrauding investors who ploughed their money into this hare-brained scheme.

Shame he couldn't have paid them off with the Arab billions.
posted by PeterMcDermott at 3:23 PM on November 21, 2006

ugh!

its. its. its.

No, you were right the first time. But it's comforting to know that you care.
posted by Brak at 3:27 PM on November 21, 2006

This thread needs some dramatic music to make it more conspirational. I heard the Duh, duh DUHHHHHH music when I read to the poisoning (which, by the way, is a link to the Wiki on the water fuel cell and, as far as I could tell, had nothing to do with Meyer's death).

Is it safe to say that The Water Engine is based on this story? Because that was a pretty decent little made for teevee movie.
posted by fenriq at 3:46 PM on November 21, 2006

I have recently had an insight into a perpetual motion machine, inspired by recent media coverage of space elevators. The idea is that the space elevator has a hollow straw in the middle of it that connects sea level air pressure to the vacuum of space.

It works through air rushing up the straw due to the differential in air pressure which drives a turbine that generates electricity, or powers a climber on the space elevator itself. The air then goes shooting out into space and is then slowly drawn back into the atmosphere by the use of gravity.
posted by Samuel Farrow at 3:46 PM on November 21, 2006

Samuel Farrow writes "It works through air rushing up the straw due to the differential in air pressure which drives a turbine that generates electricity, or powers a climber on the space elevator itself."

I'm pretty sure that the mass of the column of air would keep if from just rushing out into the vacuum of space. It would equilibrate to a static column of atmospheric pressure at the bottom and decreasing pressure as you go up. Just like the atmosphere, which doesn't rush out into space because of the difference in pressure. It's held in place by gravity.
posted by mr_roboto at 3:52 PM on November 21, 2006

From their website:
"There are three known different forces/fields. They are gravity, magnetism, and voltage."

Uh, er... In my universe we have gravity, strong nuclear, weak nuclear and electro-magnetic.

Then he goes on....

"A Point to Ponder: How can there be an arc, if there are no electrons to leak?"

Indeed. So all you need is electron free matter with very high static charges. Gah! Just typing that hurt my brain!

There's more but you see where I'm going. In the end of his description of the process we get two hydrogen ions hanging around at our negative electron free anode. Where do they get the two electrons they need to to create the hydrogen molecule that we're going to want for combustion? How much energy is there in a hydrogen hydrogen bond and where will it come from?

The whole thing reads like a bad tribute to Alan Sokal.
posted by Kid Charlemagne at 3:53 PM on November 21, 2006

It works through air rushing up the straw due to the differential in air pressure

Why wait for a Space Elevator - put a long tube into deep water, and use the pressure difference with sea level to drive a turbine! My god, how can we have missed this so long! THIS IS HOW THEY BUILT ATLANTIS!
posted by freebird at 3:54 PM on November 21, 2006

freebird - I am happy you see the potential, unlike some out there whose vision and imagination are so restricted and confined by the laws of physics.

Btw I am looking for investors.
posted by Samuel Farrow at 4:03 PM on November 21, 2006

IANAE, I would however like to see this technology's research continued. By far not the most "batshit-insane" idea ever. I would have found a sassy link for that bat-shit insane quip, but I've got one foot out the door. I'm on my way to see Queensryche Operation Mindcrime 1 AND 2!. HOB Nola. Goodnight Mefites!
posted by winks007 at 4:13 PM on November 21, 2006

Wow. His machine had a little bone, huh?
posted by Twang at 4:21 PM on November 21, 2006

what the fuck is this, conspiracy week on mefi?
posted by spiderwire at 4:32 PM on November 21, 2006

So when can we expect a link to the interview with the CIA operative who admits to "picking up a little takeout" at the restaurant where Meyer was enjoying his last meal? [cue dramatic music]
posted by FelliniBlank at 4:38 PM on November 21, 2006

It's actually the forces of gravity, electro-weak, and strong nuclear these days, Kid (the weak nuclear and electromagnetism are aspects of the same force, , although they seem quite separate at the kind of energies we encounter regularly).

But yeah, no "voltage" as a fundamental force. He probably meant electrical forces, but a huckster can't be expected to study physics.
posted by teece at 4:39 PM on November 21, 2006

I also had an idea for a perpetual motion machine. And it also involved space. Basically I wanted to build a giant alternator where the piece that held the magnets did not physically touch the piece that held the induction wire. I figure in the frictionless vacuum of space, you could start the thing spinning and it would just go on forever. If you put the magnets side close enough to the wire side, you would get a small amount of current, but since it didn't require any maintenance, you could just let the thing forever spin and build up power.

The only problem is that there wouldn't be any way to get the electricity back to earth.
posted by quin at 4:47 PM on November 21, 2006

<sub>I have recently had an insight into a perpetual motion machine, inspired by recent media coverage of space elevators. The idea is that the space elevator has a hollow straw in the middle of it that connects sea level air pressure to the vacuum of space.

It works through air rushing up the straw due to the differential in air pressure which drives a turbine that generates electricity, or powers a climber on the space elevator itself. The air then goes shooting out into space and is then slowly drawn back into the atmosphere by the use of gravity.</sub>

That's a very dumb idea. The weight of the air would keep it from 'rushing' out into space inside the tube, just as the weight of the air keeps it from rushing out into space outside of the tube.
posted by delmoi at 4:49 PM on November 21, 2006

Quick, who do we bomb in our H2O powered aircraft so we can control the water supply? Oh, yea, the reptilian humaniods at the oil companies.
posted by BillyElmore at 4:51 PM on November 21, 2006

I also had an idea for a perpetual motion machine. And it also involved space. Basically I wanted to build a giant alternator where the piece that held the magnets did not physically touch the piece that held the induction wire. I figure in the frictionless vacuum of space, you could start the thing spinning and it would just go on forever.

The magnetic forces would stop the magnet from spinning. Even in a "frictionless" system, the energy that comes out of the magnet's kinetic energy.

Think about it, if friction was the only thing keeping motors from running forever, you could power the whole US with a small generator on a low-friction surface.

As far as getting the energy back to earth, you just have to use a laser.
posted by delmoi at 4:56 PM on November 21, 2006

Quin, unfortunately electromagnetic induction requires energy to drive it. Your alternator would stop moving eventually.

Every force in nature satisfies conservation of energy, all of them are subject to the laws of thermodynamics. It's impossible to build some clever machine that gets around this fact. You can build a clever machine that's so complicated that you don't understand what you built. You can build a clever machine that tricks your investors into thinking that you've done it. But you can't actually do it. Converting forms of energy can at most transfer energy in an 100% efficient fashion. In practice, it's always much less than 100%. This car converts mechanical energy to electrical (alternator), electrical to chemical (alternator charges battery), chemical back to electrical (battery runs electrolyzer device) electrical back to chemical (electrolyzer uses current to seperate water), chemical to heat (burn hydrogen), and heat back to mechanical (heat drives car engine). It's absurd on the face of it. The only thing this car is lacking is a stage that involves motivating a hamster to run in a wheel by holding cheese in front of it. You can much more easily accomplish the same thing by making sure that a piece of the wheel well rubs against the tire, or by poking a tiny hole in the gas tank. Both will also sap energy from the system. They won't get many investors though.
posted by Humanzee at 5:09 PM on November 21, 2006

All I want to know is, this car is gonna fly, right? It's a flying car?

If you're gonna violate the laws of physics with a perpetual motion machine, you'd better make the damn thing fly, dammit!

Maybe this should be hooked up with the BLP folks! I bet Hydrino fractional-orbital energy can boost this even further! Wow! Take that, nature!! :D

Ah, the credulous. So entertaining.
posted by zoogleplex at 5:24 PM on November 21, 2006

You could also get the energy back to earth using microwaves.
posted by MythMaker at 5:25 PM on November 21, 2006

The magnetic forces would stop the magnet from spinning. Even in a "frictionless" system, the energy that comes out of the magnet's kinetic energy.

I knew that there would be resistance, I had just hoped if we built it massive enough, the loss would be negligible. But you are right, it's not perpetual motion.

As far as getting the energy back to earth, you just have to use a laser.

I've seen that movie: It's the one where something minor goes horribly wrong and the laser vaporizes a city.

That was a movie right? Because if not, I've got a really screwed up imagination.

Still, it's a pity it wouldn't work. It always struck me as something that would be neat to see: huge torus' spinning silently producing power for our vast space armada.
posted by quin at 5:28 PM on November 21, 2006

It works through air rushing up the straw due to the differential in air pressure which drives a turbine that generates electricity, or powers a climber on the space elevator itself. The air then goes shooting out into space and is then slowly drawn back into the atmosphere by the use of gravity.
posted by Samuel Farrow

Something like this?

http://www.solarmissiontechnologies.com/FAQs.htm
posted by Jumpin Jack Flash at 5:46 PM on November 21, 2006

quin: Actually, it's a short story by Asimov, about a robot on an orbiting power station that is so intelligent it convinces itself that it could not have possibly been built by its owner.
posted by tehloki at 5:46 PM on November 21, 2006

Oh yeah, it's called [checks...] Reason. And I just read that not too long ago too, I should have remembered it.
posted by quin at 5:51 PM on November 21, 2006

Weirdly, here's something that might actually be possible: boost a big steam turbogenerator with a specially-designed closed-loop water/steam system up into space, use a parabolic reflector to concentrate the sun's rays onto a big tank of water, generate steam to drive the turbine and crank out a crapload of megawatts that way - with which you'd power the microwave laser (maser) to beam power downwards.

Sounds crazy, right? But it's doable with only a few engineering problems to solve. Why don't we do stuff like that? Because turbogenerators are pretty heavy, which means they'd cost a lot to get to orbit. There are other basic considerations like dealing with torque and gyroscopic effects in free-fall, sure. Of course, SF writers have been talking for decades about boosting solar panel arrays sized in kilometers up into space to beam down power, which represents one hell of a lot of mass to boost. We use solar panels on current stuff because they're light, but we'd need to make 10 times the amount of solar panels (a very energy intensive manufacturing process, not to mention environmentally dirty if considering our standard silicon panels) than have ever been made in order to make one huge solar array.

How about we engineer some super-lightweight turbogenerators/alternators with systems that can fly in space, and see if we can test out that whole process (including power beaming by microwave) with some known technology? If we can put up a few hundred tons of space station, we ought to be able to put up a couple tens of tons of turbine/alternator/steam loop with water, eh?

I mean, it's crazy, but what the hell? Sure makes more sense than any lunatic's water-powered car or perpetual motion machine...

JJFlash: That might be what he's thinking of, but that runs on air pressure differential caused by a heat gradient. Just like all the wind and weather on earth. Actually it's an interesting idea, just might be viable.
posted by zoogleplex at 5:55 PM on November 21, 2006

zoogleplex, that's a fine idea, but wouldn't it be easier to put it on earth instead? No one's really using New Mexico.
posted by pinespree at 6:14 PM on November 21, 2006

which represents one hell of a lot of mass to boost. We use solar panels on current stuff because they're light, but we'd need to make 10 times the amount of solar panels (a very energy intensive manufacturing process, not to mention environmentally dirty if considering our standard silicon panels) than have ever been made in order to make one huge solar array.

As long as we're talking pie-in-the-sky, why not just throw a handful of nano-bots up on the moon with a few instruction sets: 1) self-replicate, using the plentiful ores of the moon as source material, until you hit a critical number, 2) manufacture panels to cover a sizable area on the surface of the moon that faces the sun consistently. That way, you get over the boost problems.

The only thing you have to worry about, then, is the nanobots developing self awareness and using the maser to fry up the populace on the planet.
posted by thanotopsis at 6:19 PM on November 21, 2006

wait! i got it! it's a game where the section headers from biographical entries in wikipedia are read and the players have to guess who the entry is about! and some dork always starts yelling out names as soon as the reader says "early life"

maybe the game could be called early life.
posted by snofoam at 6:26 PM on November 21, 2006 [3 favorites]

No argument from me, pinespree. It's a lot cheaper if we don't have to boost it to orbit! The problem with that, though, is the transmission over power lines. There are major losses attached to that, at least with AC, that limit the distance you can send electricity effectively. We can't run the whole North American grid from stations in the desert southwest...

However, the advantage to being in orbit is that you can place yourself where the sun shines at all times, and the sunlight is unfiltered and most powerful. Also, you're not taking up anyone's real estate. There is that pesky problem of solar flares and coronal mass ejections though... probably not so good for any electrical generation system up there.

I'm only actually thinking of this wild-ass idea as a testbed for the microwave thing, and maybe as practical generation for orbital stations etc. It's probably not something that would scale for day to day use down here... but neither is kilometers-long-and-wide photovoltaic panels, eh?

thanatopsis: Hey, that sounds great! we can build the nanobots with the Three Laws, can't we? :D

Actually, I don't think any of the moon faces the sun consistently. Plus, if we're that good with nanobots, we can have them build a mass-driver and shoot all them silicon panels up to L5!

I grew up reading a lot of that SF and science-prediction that thought we'd get up there to space and start living there permanently. I still think we have the potential to do it, but we'd have to stop wasting energy and materiel blowing each other up and get everyone fed, first, most likely. Colonization and industrialization would require the efforts of pretty much everyone on earth for a good few centuries. I don't think we're gonna make it, we can't even agree about completely imaginary sky gods. (Sorry, Larry, Jerry and Fred...)
posted by zoogleplex at 6:30 PM on November 21, 2006

quin,

I knew that there would be resistance, I had just hoped if we built it massive enough, the loss would be negligible.

It's more than that, really. It's not friction that stops your alternator -- your space alternator, to a first approximation, could spin well-near forever once you spun it up, as long as you didn't hook it up to anything.

As soon as you close the circuit the energy bound up in the spinning rotor gets sucked out to run the light bulb/joy buzzer/whatever your load is. And you can never get more energy out of the device than you put into spinning up the rotor, even if your bearings are completely frictionless.

It's hard to picture without understanding that an alternator really just transforms energy from one form (mechanical -- the work put into spinning the rotor) into another (electrical). It's too bad, really, or else the self-powered car I invented would have made a mint and I'd be buying us all frosty chocolate milkshakes.
posted by Opposite George at 6:33 PM on November 21, 2006

The only thing you have to worry about, then, is the nanobots developing self awareness and using the maser to fry up the populace on the planet.

IM ON UR MOON COOKIN UR DOODZ
posted by Opposite George at 6:36 PM on November 21, 2006

Actually, Opposite George, that sparks another ideer in me skull... another wild one, too.

How about a "paddle wheel," just like an old water wheel, except it runs on solar wind? Solar wind turbine. 10 kilometer mylar film wings. Free-floating in space. Gotta figure out how to keep it from blowing away, but what the hey!

Yep, I'm crazy, yep.
posted by zoogleplex at 6:39 PM on November 21, 2006

zoogleplex,

It's so crazy it might just work. You aren't breaking any laws of thermodynamics, anyway.

I fully expect a milkshake out of this, btw.
posted by Opposite George at 6:43 PM on November 21, 2006

I'll whip up some of those awesome Shamrock Shakes!

Actually, there was an actual experiment where they lowered a length of cable from, I believe, the Space Shuttle, to see if they could generate a current simply by the motion of an orbital object thru the earth's magnetic field. As I recall it worked too well - so much current was generated that the wire burned up from the overload. I don't have time to google it, I have to go home, so go diggin'...

If we're going to try anything crazy, that actually seems more promising to me. Turn the orbital object into a free-falling rotor with Earth as stator. Then the challenge is to hold the microwave beam from the LEO generator to a GEO "accumulator," and thence beam the power down to earth.
posted by zoogleplex at 6:49 PM on November 21, 2006

Well, the problem is that as soon as you start tapping the energy from the generator its orbit will start to decay. The solar wind thing works b/c you're taking the energy from the Sun, so you don't have to put anything into the wheel.
posted by Opposite George at 6:57 PM on November 21, 2006

The Space Tether Experiment.

I think your problem will be with the microwave power beam. It worked well in G.I. Joe: The Movie, but I'm not aware of any real-life long distanec transmission of power by microwave beam.
posted by b1tr0t at 6:57 PM on November 21, 2006

Aha! zoogleplex, I have it!

What we do is put folding wings on your rotor and extend them to give it a solar wind kick when it's on the "away from the Sun" part of its orbit, then fold 'em back and let it coast down on the way back. We just need to make sure we get at least as much of a kick as we take out from the tether in each cycle.

We will be rolling in milkshakes* yet. Well, not literally rolling in them, of course. That's just a little too weird for me (not that there's anything wrong with that.)

[/Mad?!? Mad you say?!?]
posted by Opposite George at 7:12 PM on November 21, 2006

This is what separates MetaFilter from crazy perpetual motion inventors. Specifically, step 3:

1: Alice: "I have an idea. We could do X."
2: Bob: "No, that wouldn't work because of Y."
3: Alice: "Oh, you're right."
4: Alice: "What about, instead of X, Z?"
5: GOTO 2
posted by Bugbread at 7:18 PM on November 21, 2006

fenriq, if you read the whole wikipedia entry, you'll see they mention his death by poisoning under the "Meyer's water-fueled car" section.
posted by banished at 7:42 PM on November 21, 2006

The solar wind/paddlewheel idea is simlar to the radiometer, of which millions have been made. However, this would not work in a vaccuum; some air molecules are necessary for the thermal behavior involved in the rotation.

If you could put the object in partial shadow, by for example anchoring it to an asteroid such that the returning vanes were shaded by the asteroid body, it would work. The asteroid would have to be nonrotating -- or more accurately, tidally locked to keep the same face to the sun, which means it would rotate once per orbit.
posted by George_Spiggott at 8:08 PM on November 21, 2006

George_Spiggott,

The Crookes Radiometer is isolated from interaction with the solar wind. BTW, the solar wind is plasma, not photons, and we've all seen sailboats run downwind so I don't see the problem.

Changing the object's solarwindodynamic profile serves the same purpose as shadowing the vanes turning towards the sun. For the radial alternator, you could extend or rotate those vanes so as to present almost no surface to the solar wind. For the tether orbiting the earth, you'd do the same for the whole thing on the upwind leg.

But even if there was no solar wind, there's no reason to believe photons couldn't push an object around. It just wouldn't work like a Crookes Radiometer (and there's nothing wrong with that.)
posted by Opposite George at 8:42 PM on November 21, 2006

s/those vanes/the vanes on the upwind leg/
posted by Opposite George at 8:44 PM on November 21, 2006

Also, you're not taking up anyone's real estate.

Except, I wonder, now-blocked bits of the night sky? How much visual real estate would solar panels take up?

And besides New Mexico being a good place for solar panels, there's big chunks of W. Texas where ain't nothing happening. Except the Marfa lights.
posted by emjaybee at 9:57 PM on November 21, 2006

Opposite George, if you're dead set on extracting power from the solar wind, why not skip the multi-step solar wind to mechanical to electrical process an instead use an "inverse" ion thruster to directly convert the stream of charged particles to electricity?

Of course there are a number of practical complications to overcome. :-)
posted by RichardP at 10:20 PM on November 21, 2006

RichardP, no strong preference for using the solar wind, just riffing on zoogleplex's idea. But that reverse ion thruster thing sounds good too.

I hope whatever's best starts cranking soon. I'm going to need the energy to perfect my race of atomic supermen which will conquer the world.
posted by Opposite George at 10:57 PM on November 21, 2006

But yeah, a really big pipe w/suitably situated magnetic loops/electrodes oughta do it. Getting the power back to earth is left as an exercise for the reader (I'm the big-picture guy on this project, see?)

We'll put the powerplant downstream of Earth so as not to affect the northern/southern lights. On second thought, my supermen come first so fuck the aurorae. We're totally parking our bad boy @ L₁
posted by Opposite George at 11:16 PM on November 21, 2006

RichardP : Opposite George, if you're dead set on extracting power from the solar wind, why not skip the multi-step solar wind to mechanical to electrical process an instead use an "inverse" ion thruster to directly convert the stream of charged particles to electricity?

Yeah, it probably wouldn't work, but this is why I love the MeFi, RichardP, the deep-geek in me is developing a sort of nerd-crush on you.

I know nothing of math or science, but when I finally commit my low budget sci-fi script to paper, I will look to you to make this shit work. Because that statement needs to be in a film script. Even if you are a total lunatic, it sounds good.
posted by quin at 11:50 PM on November 21, 2006

"...put a long tube into deep water, and use the pressure difference with sea level to drive a turbine..."

Not exactly the same, but you should look at this. If you and delmoi and others were right that in principle something like what was mentioned couldn't work, then piped lake degassing wouldn't work. My guess is that you could get some kind of chimney action self-perpetuating using unheated ground-level air as long as the chimney crosses a thermocline and you initiate the process. That's just an intuitive guess meant to illustrate the general idea that what we're talking about is a sort of a siphon.
posted by Ethereal Bligh at 11:57 PM on November 21, 2006

Your favorite perpetual motion machine sucks with no apparent energy source.

Young man, as long as you live under my roof, you will obey the laws of thermodynamics!
posted by jonp72 at 1:11 AM on November 22, 2006

We use solar panels on current stuff because they're light...

True, zoogleplex, but there is another reason: They don't work by thermal gradient (unlike steam generators) so they don't need an enormous heatsink to keep from reaching thermal equilibrium.
Earth-bound steam generators used for power generation can use air and/or water for cooling (that's what those huge cooling towers are for). Can't do that in space. The only way to get rid of excess heat is to radiate it.

The weight of the steam generator would be the least of your problems.
posted by spazzm at 2:20 AM on November 22, 2006

Ethereal Bligh:
No, still won't work.
Lake degassing works because of the gases in the deep water.
As the water rises, pressure drops and the gases are released as bubbles - exactly as when you open a soda bottle (it's the same gas, even). The gas bubbles rise to the surface, pulling some water along.

Air is a gas, so the same trick won't work - any precipitate will have to be solid or liquid. Which will fall, not rise.
I'm not sure, but I don't think it's likely seawater contains enough dissolved gases to pull of the same trick.
Then there's the possibility that degassing the oceans would increase the carbon dioxide content of the atmosphere - carbon dioxide is a greenhouse gas.
posted by spazzm at 2:30 AM on November 22, 2006

It's fun to watch blind people chasing invisible butterflies. They churn up so much dust! Still, if anyone can catch an invisible butterfly, it is a blind person.
posted by Opus Dark at 3:04 AM on November 22, 2006

StarForce5 is my new best friend.

There is an angle you are all missing here, of course.

Humanoid lizard chauffeurs. Who cares if the car runs on water, when you've got a giant lizard to drive you places?
posted by ewkpates at 5:03 AM on November 22, 2006

Various nut-pages that believe that Stan Meyer actually drove a water-powered car from New York to the planet Venus (or something) allege that he achieved this feat in the company of Dennis Lee.

Dennis Lee is still very much alive, and still accepting as much investment money as he can get from people interested in his own not-a-perpetual-motion-machine. You can read all about him here.
posted by dansdata at 8:49 AM on November 22, 2006

Sorry I'm late to the party but here's my idea:

Building on the straw-in-the-ocean idea and beaming power down from space thing, how about using fiber optics to transmit solar energy down to mile deep ocean water at the bottom of the tube? The solar light would heat the water, which would rise, powering the turbines, &c...

Snark in 3..2...
posted by daHIFI at 9:44 AM on November 22, 2006

"Can't do that in space. The only way to get rid of excess heat is to radiate it."

Ah HA! I knew I'd left something out!!!

grumble back to the drawing board grumble...

Well, it *is* possible to radiate heat away in space, though. Otherwise our astronauts would all burn up fast up there. Spacesuits don't have heating systems, only cooling systems; I'm sure the same is true of the ISS. So, there's probably a way to do it, would just require some radiator-design innovation. You'd have to isolate (shade) the radiator surfaces from the sun. Space is pretty damn cold as long as you're not in direct sunlight.

I hope everyone realizes I'm engaging in hyperbole in all these posts, right? :)

"if you're dead set on extracting power from the solar wind, why not skip the multi-step solar wind to mechanical to electrical process an instead use an "inverse" ion thruster to directly convert the stream of charged particles to electricity?"

That's not a bad idea!

Still, I think attempting some kind of system that uses satellites whirling thru the geomagnetic field might have some promise...

"I think your problem will be with the microwave power beam. It worked well in G.I. Joe: The Movie, but I'm not aware of any real-life long distanec transmission of power by microwave beam."

Well, I don't think it's been tried yet, but at least that's something we could probably actually build and test. We know how to build masers, we know how to build receiving antennae, and we have some expertise with various means of holding two moving objects in proper orientation to each other. Would seem worth some practical experimentation.

I'm sure it wouldn't be too hard to test a static system in a laboratory. Actually, we probably don't need to. Beaming microwaves at an antenna and converting them to current has been done for decades by long-distance TV and data transmission. Remember those big "drums" and "horns" that used to be on buildings all over, and can still be found some places?

To scale it up we'd certainly have to try it with higher energy levels. The idea that some scientists and SF writers advanced involved making the receiving antennae very large, a lattice covering square miles of Arizona or Nevada, under which the microwave flux hitting the ground would be negligible - so as to avoid having an error with a multi-megawatt maser beam vaporising a city... that seemed a bit farfetched because over all those miles there'd be electrical losses over all that wire, yes?

Y'know, we'd probably do ourselves some better service if we just figured out how to cut our total energy use by 50%. I bet that's a hell of a lot easier and cheaper than any wild-ass pie-in-the-sky scheme. Hell, I was able to cut my electric use by more than that back during our "California Energy Crisis brought to you by Enron!" days, just by turning off my "extra" computers (I had like 5 of them running networked 24/7, doh) and replacing all my light bulbs with compact fluorescents, and of course turning off the damn lights when I'm not using them. I'm only just now seeing those bulbs burn out, so they really do last 5 to 6 years.

And not trying to make perpetual motion water powered cars that violate the laws of physics.
posted by zoogleplex at 11:45 AM on November 22, 2006

I just watched the "it runs on water" google video.
It's a ridiculous show - full of misrepresentations.
There are the factual errors, where they claim that the device uses very little energy, only a few milliAmps. Energy isn't measured in Amps - a current of a few milliAmps can carry a lot of energy if the voltage is high enough.

They also represent the laws of thermodynamics as mere stodgy conventions that could easily be circumvented if the scientists (who, apparently, enforce the laws of thermodynamics) weren't so 'bullheaded'.

But the worst misrepresentation is when they give the impression that it is the job of scientist to disprove all these claims despite the inventor's secrecy. If the inventors crave scientific investigation that much, why don't they make their designs public?

These people have all the hallmarks of cranks.
posted by spazzm at 2:47 PM on November 22, 2006

Which reminds me, you should all check out crank.net, especially their perpetual motion section.
posted by spazzm at 3:02 PM on November 22, 2006

daHIFI: sure, that might work. You could also take the equivaltent area of fiber optic cable and just cover that area with solar cells, and almost certainly get better efficiency without the trouble of building a mile-deep ocean power station. All the people trying to get at the energy "stored" in temperature/pressure gradients in the atmosphere should understand that they're in hydrostatic equilibrium. Hydrostatic equilibrium exists precisely so that energy is not gained or lost if material rises or falls. You may be able to exploit these gradients in some sort of power scheme, but you could probably get at that power more efficiently with some other method.

zoogleplex: objects in space radiate energy away like a black body. here's an example describing how planets radiate. The problem is that the efficiency of a steam turbine is at most:
Max Efficiency = 1 - Temp Radiator / Temp Steam
(the temperatures are in Kelvin). On Earth, we can make steam power generators very efficient by making steam super-hot and cooling the waste heat off in a lake. In space, you just have to wait for black body radiation to cool you off, so the temperature of the radiator is likely to be very high, giving terrible efficiency. Combine that with the expensive of servicing all the moving parts of your turbine, and you'd definitely be better off with solar panels.
posted by Humanzee at 3:43 PM on November 22, 2006

Right on. Thanks, very cool, Humanzee!

Uh, or actually not... very cool, as it were. Heh.
posted by zoogleplex at 3:55 PM on November 22, 2006

I just watched the video, and for their comment that there wasn't a lot of power being drawn.....

....the lights in the lab dimmed when he switched things on.

Yeah....cause THAT always happens when there is no drain on the house current....
posted by dwivian at 5:06 PM on November 22, 2006

He may think its a perpetual motion machine, but there is actually a really easy explanation:

Whatever is in the metal pipes is binding with the oxygen instead of hydrogen. The electricity is just a catalyst, hydrogen is freed and something (aluminum oxide) precipitates out the bottom.

The part of the equation that balances it is the electricity needed to make non-oxadized metal (aluminum), and the downside is that his machine only runs until all the metal is oxidized.

There was a fellow who made a motorcycle based on this, using aluminum wire. (I can't find the link)

It is not free energy, but it is a nice safe way to haul around a ton of hydrogen, freeing it as you need it. (At the 'gas' station, you add a spool of wire and water, dump aluminum oxide powder)
posted by rubin at 7:17 PM on November 22, 2006

"The gas bubbles rise to the surface, pulling some water along. "

But they don't. Nature doesn't abhor a vacuum. The gas bubbles are pushed up by pressure below just like everything else is. So there's not the qualitative difference there that you think there is. Which was my point.

I've come across a theoretical super-lightweight wind chimney from ground-level to relatively high in the atmosphere that doesn't heat the air at ground level and, once primed, is self-running. It was written by a physicist, I trust it. I don't have the details, I wish I did.

Your view is the one that is intuitively correct to me, but when I look at it very closely then I realize that it denies lake degassing, too. The gas precipitating from water seems like the important thing, and it is, but not in the way it seems. It's important thermodynamically. And my most abstracted intuition tells me that siphoning is a good abstract model for what I think is going on: you can get over a energy hump if you're going to a lower state where there's a mechanism to do so. And I have particular observation in mind, as well: we already know that the atmosphere is not static and that self-perpetuating "pipes" exist in the form of hurricanes and other less distinct phenomena.
posted by Ethereal Bligh at 9:11 PM on November 22, 2006

Ethereal Bligh : Nature doesn't abhor a vacuum.

Clearly you haven't been to my house when the carpets need to be cleaned, my pets freak the fuck out.
posted by quin at 9:18 PM on November 22, 2006

One thing that you're not taking into account is that the lakes that you're talking about are inherently unstable. They degass on their own in massive events, killing people. To prevent this from happening the pipes are inserted to degas the lake slowly and safely.

These lakes are still, with no mixing; and they have CO2 gas being introduced at the bottom. The ocean is a completely different system, because it's well-mixed due to ocean currents.

A system that's simply in hydrostatic equilibrium can't be used to extract power. If the system that you described actually works, it's because (like the degassing lakes) the system has something else going on.
posted by Humanzee at 10:32 PM on November 22, 2006

It was written by a physicist, I trust it. I don't have the details, I wish I did.

Well, that convinced me!
posted by spazzm at 1:01 AM on November 23, 2006

Maybe a wind chimney could work if the top opening was pointing downwind and it was blowing enough. But it would have to be a thicker pipe - it would be at lower pressure than the surrounding air, so air presssure would squeeze it shut if it wasn't thick enough. But then again it would only harness wind power - and there are simpler ways of doing that.

Someone mentioned hurricanes - they're driven by heat, not gravity, thus they have more in common with the aussie solar tower than the chemically-driven lake degassing fountains.

These lakes are still, with no mixing; and they have CO2 gas being introduced at the bottom.

Exactly. The degassing pipes don't run on water pressure - they run on volcanic chemicals.
posted by spazzm at 1:16 AM on November 23, 2006

The air at ground level is under gravitational pressure, but it's also hotter than the air above it. I think that if you get a column of hot ground-level air moving upward it will continue moving upward because it will be warmer than the air surrounding it. An artificial chimney is just something to facilitate a process that happens on its own. You can see this all over the place. The ultimate source of a convection current is the energy pumped into it by a heat source, and that's what's happening to ground-level air and the Sun. Ultimately, the Sun is pumping energy into the system mostly near the ground in water-laden air.

"Exactly. The degassing pipes don't run on water pressure - they run on volcanic chemicals."

Not exactly but close enough for government work. If you thought I was saying a wind chimney would work on pressure alone—it being the only relevant characteristic of the system—then you misunderstood me or I wasn't clear. It's a thermally-driven system utilizing the pressure differential. I mentioned crossing the thermocline in my first comment.

I think my lake degassing example confused much more than it helped. But you're wrong to think that was is happening there is a chemical reaction, it's not. It's just CO2 being liberated from water it was dissolved in under pressure. That system is about the pressure and the thermodynamics of what exactly is different when the CO2 is dissolved and when it's released.

Anyway, I realize I that what I should have said was that an atmospheric convection current that is artificially stabilized and doesn't require an additional heat input (over what is already present at ground-level) is theoretically possible. I don't know how much energy you could extract from it mechanically...probably not much. What it would be good for, and the context in which I encountered this idea, was for moving moist air high into the atmosphere and causing cloud formation.
posted by Ethereal Bligh at 1:41 AM on November 23, 2006

Nature doesn't abhor a vacuum. The gas bubbles are pushed up by pressure below just like everything else is. So there's not the qualitative difference there that you think there is.

That's a valid point, and it took me a while to come up with an explanation that satisfied me:

The CO₂ bubble is, as you correctly state, pushed up by the denser water that surrounds it. As the bubble rises, water is pushed in beneath it. Where does the water come from? Well, it can't come from above - that's where the bubble is. So it must come from the sides and from beneath. Thus, more water flows in from beneath than from above, and the net movement direction is up. Likewise, the water above the bubble is forced away by the bubble - it moves either to the side, or up. Again, the net direction is up.

However, the lake will not be permanently raised by this, so there must be downward movement somewhere. But since that downward movement is going to be mostly outside the tube, the net movement of water (as a result of the rising bubbles) is going to be up.

As the water in the tube rises and sprays out at the top, the pressure inside the tube falls. As the pressure falls, more bubbles are formed - the process is self-sustaining. All it needs is a little help to get started and, crucially, water with lots of dissolved gas.
posted by spazzm at 1:45 AM on November 23, 2006

the net movement of water inside the tube (...) is going to be up.

Sorry.

Now, if there was only a way of generating energy from interminable internet discussions...
posted by spazzm at 1:48 AM on November 23, 2006

Ethereal Bligh, I don't think we're going to reach consensus on this by discussion alone. I suggest you build the type of chimney you mention and test it. If it works, if it can be shown that it's not merely harnessing wind power and if the experiment is repeated by other with the same result, I'll be the first to congratulate you.
posted by spazzm at 1:56 AM on November 23, 2006

That's a good description, except I'd say, of course, that the net movement of the water would be zero. :) That magic here is in the liberation of the CO2 in conjunction with the relative incompressibility of water. That's my guess.

Anyway, I'm just posting again to make clear that it's been me who's been confused—my lake degassing example led me astray into more general thoughts about something that I knew but sort of forgot was really just about convection with regard to the wind chimney, which was the whole point of my comment.

A bit more rumination while I've typed this comment has led me to think that the lake degassing thing happens because of the combination of the fact that water is relatively incompressible and that there's a discontinuity where the degassing CO2 comes out of solution—suddenly, the mixture of CO2 bubbles in the water weighs much less than the water around it. Just as you say.

On Preview: spazzm, a convection machine would obviously work. I don't know why you have a problem with it. If you start warm ground-level air flowing up high enough, it will reach a colder layer and will continue rising on its own accord (so to speak). What happens after that is what happens in your lake degassing description. The energy driving it is the Sun heating the ground. Like I said, if one were to build such a structure to stabilize this and, unlike the solar chimney, didn't rely on a greenhouse to heat the ground level air further, I don't know if you could extract that much energy from the system mechanically. I doubt you could, thus the acres of greenhouse for the proposed solar chimney. But, as I said, a smaller, unheated structure would still transport warm and moist air high into the atmosphere where it will create clouds. Which might be useful.
posted by Ethereal Bligh at 2:07 AM on November 23, 2006

If you start warm ground-level air flowing up high enough, it will reach a colder layer and will continue rising on its own accord (so to speak).

Except, of course, the warm air will be inside the tube and the cold air is outside the tube. The air outside the tube can't force the air inside the tube upwards because they're separated by an impermeable membrane.

But, of course, I might be wrong. It's been a long day and a few glasses of wine. So please; prove me wrong.
posted by spazzm at 2:26 AM on November 23, 2006

Ethereal Bligh, I was wondering if you were talking about solar chimneys. In that case the air at the bottom has been deliberately heated, thus taking it out of equilibrium. My understanding is that all solar chimney designs use a large solar collection area covered essentially by a greenhouse, thus raising the air temperature at ground level above what it otherwise would be.

Wikipedia also has a nice entry on limnic eruption that describes the circumstances of eruptions, as well as how the degassing procedure works.
posted by Humanzee at 9:18 AM on November 23, 2006

Humanzee, you're only skimming what I've written. I'm talking about an "unheated" solar chimney, but that doesn't matter. An unheated solar chimney is still heated. The atmosphere is not in a hydrostatic equilibrium, locally at least. Hotter air is below colder air.

"Except, of course, the warm air will be inside the tube and the cold air is outside the tube. The air outside the tube can't force the air inside the tube upwards because they're separated by an impermeable membrane."

You're misunderstanding buoyancy. The air is pushed from the bottom because of the greater weight outside the tube pushing downward, not from the side. The classic experiment that demonstrates this is submersing (and filling) a long plastic tube in a large bucket of water. Clamp an end of the tube and then lift that end from the water. You'll pull the water up inside the tube until about 32 feet, at which point it stops and won't go any higher no matter how much you continue to raise the tube. That's because a same-diameter column of air, from that starting height to the top of the atmosphere, weighs as much as that ~32 foot column of water. But my point is that the tube doesn't need to be plastic—it's only plastic for the convenience of the experiment. It could be rigid steel. It'll still support a column of water 32 feet high. Buoyancy isn't pressure from the side, no matter what intuition tells you.
posted by Ethereal Bligh at 9:47 AM on November 23, 2006

Ethereal Bligh: Actually I read what you wrote really carefully (several times in fact), but I assumed you were talking about the kind of solar chimney that I'm familiar with, and were just misspeaking. Evidently I was wrong. If you can find any information about the kind of solar chimney you're talking about, I would be very interested.
posted by Humanzee at 10:15 AM on November 23, 2006

"Evidently I was wrong."

Hmm. But I wrote several times something like "unheated ground-level air" and once contrasted what I described with the solar chimney's greenhouse heating, also making the point that the greenhouse heating of the solar chimney is what makes it useful (a lot more energy).

I did a cursory web search on what I have in mind, but didn't find anything. But now that I'm no longer confused, and no longer confusing the issue by talking about lake degassing, I don't see where the controversy is. All I'm describing is a convection current. Whatever it is that sustains the thermocline between the lower, warmer air and the higher, colder air is artificially overcome with a chimney and its priming. After that it's self-sustaining just like any other convection current with a continued heat source.
posted by Ethereal Bligh at 10:34 AM on November 23, 2006

I assumed that by "unheated" you just meant "not heated by humans" (i.e. no burning anything, whatever). In retrospect, I shouldn't have assumed that.

I agree that there are naturally-occurring updrafts all the time. So a chimney like that ought to work for awhile, provided it's put in the right place (after all, there are downdrafts too, and places where the air is pretty still). It's not obvious to me that the chimney wouldn't eventually stop due to winds, pressure fronts, cloud cover, changes from night to day, etc. The solar chimneys I've seen described all have large collection areas (in part) so that they have a really large mass of heated air, and can keep working during extended periods of those sorts of fluctuations. I think that it would be interesting to read about the differences that come from not having a collector like that. I'll keep an eye out for it in the future (and I'll try not to jump to conclusions too).
posted by Humanzee at 11:06 AM on November 23, 2006

You're misunderstanding buoyancy. The air is pushed from the bottom because of the greater weight outside the tube pushing downward, not from the side.

Maybe I am misunderstanding buoyancy.
Explain to me what's wrong with this:
The pressure at the top of the tube must be higher than the pressure of air around it, otherwise air won't leave the tube and there will be no flow. So the pressure at the bottom will have to be equal to the pressure at the top plus the weight of the air in the column. The pressure outside the bottom of the tube will be just the weight of the equivalent column of air - less than the pressure inside the tube. You think you can offset this by introducing hot air into the tube - sure you can, but you'll need an external heat source (like a large greenhouse or furnace) to heat the air.

The natural temperature variation is not enough - it is largely a function of the fact that, in a gas, pressure and temperature is linked. As the 'hot' air in the tube rises, the pressure falls and thus the temperature.

The classic experiment that demonstrates this is submersing (and filling) a long plastic tube in a large bucket of water. Clamp an end of the tube and then lift that end from the water. You'll pull the water up inside the tube until about 32 feet, at which point it stops and won't go any higher no matter how much you continue to raise the tube.

Yes, but it's not the force of gravity that lifts the column - it's merely keeping it from falling down. You are lifting the column, by the act of lifting the tube. If you measure the force necessary to to lift the tube when it's full, it is equal to the weight of the tube plus the weight of the water inside. You cannot use this phenomenon to make the water lift itself to a higher level.

Think about this: You have a vertical tube, one end submerged in water. Start the water flowing, so that it flows out the top of the tube, using a pump or similar. When you stop the pump, will the water keep flowing of its own force?

The siphon example is misleading, because it relies on water flowing to a lower level.

What you're proposing sounds like forcing air to move against the force of gravity, powered by nothing but the force of gravity. Which, as the laws of thermodynamics tell us, is impossible.

But, as I've said before: I hope I'm wrong and that you prove this by building a working demonstration and publish the specifications so that others can replicate your experiment. I look forward to reading it.
posted by spazzm at 3:37 PM on November 23, 2006

Another problem with the chimney that we haven't touched on yet is that even if you got a column of air rising, the pressure and therefore temperature of the air would fall as it rose, thus causing precipitation of water vapour. The resulting rain inside the tube would counteract the upward movement of the air.

There's just no way that the chimney would have a self-sustained, permanent (or even long-term) airflow through it.
posted by spazzm at 4:00 PM on November 23, 2006

"You cannot use this phenomenon to make the water lift itself to a higher level."

I didn't mean to imply that it would. My example was to demonstrate why the rigidity doesn't matter and to explain that buoyancy is force from below, and only below.

"You think you can offset this by introducing hot air into the tube - sure you can, but you'll need an external heat source (like a large greenhouse or furnace) to heat the air."

It's really weird that you and humanzee aren't getting this: the Sun is heating the air mostly at ground level. You guys are thinking of this like there's just a pressure gradient due to gravity and that's it. But the air near the Earth's surface is heated both by the Earth (which absorbs more heat than the air does directly from the Sun) and because it is more humid. It gets hot while the air above it doesn't. That's not a stable system—convection currents will arise to mix the layers. All I'm describing is a structure that gets the process started (with fans) and acts to stabilize it (the chimney).

As soon as you displace some hot air upward, then the whole column is shifted upward and the air travels to the top—all along the way it will be hotter but under the same gravitational pressure as the air around it. It will rise. I'm still only describing a common convection current. With a wall around it. As long as the Sun keeps heating the ground air, indirectly and directly, to be hotter than the air above it, the current will continue.
posted by Ethereal Bligh at 9:50 PM on November 23, 2006

In other words, the atmosphere during daylight is (almost) always and everywhere being heated from below, just as in the solar chimney, only not as much.

This is why we have weather.
posted by Ethereal Bligh at 9:54 PM on November 23, 2006

It's really weird that you and humanzee aren't getting this
Please, I've reformed! I made foolish assumptions about what you meant, and I repent! :) I agree that the solar tower as you've described would work, and at this point, I'm just curious how it would handle things like nightfall, large storms, or a series of cloudy days.
posted by Humanzee at 10:26 PM on November 23, 2006

It would probably stall under some conditions. I thought earlier that you could probably paint it black or something similar and that would probably restart it after it stalled. The real solar tower with its greenhouse would probably stall under some rare conditions, too, but restart itself pretty quick.

Just to remind: I encountered this in the context of doing nothing more than lifting hot humid air up into the atmosphere to generate local precipitation. That may not work, either, but it's a modest goal compared to generating power. I mean, actually generating rainfall is a significant energy transfer in itself, so you'd probably need a bunch of these for that. I was wondering, though, if you could use it to change local climate, such as a desert separated from a hot, humid coastline by a mountain range where the prevailing winds in the upper atmosphere most to the desert.
posted by Ethereal Bligh at 10:33 PM on November 23, 2006

Wouldn't "stalling" just mean that tower would equalize in the other direction (down)?
posted by spiderwire at 3:57 PM on November 24, 2006

The first time I read this headline, I thought it said Water Powered Cat.
posted by etoile at 2:17 PM on November 25, 2006

My example was to demonstrate why the rigidity doesn't matter and to explain that buoyancy is force from below, and only below.

This isn't really pertinent to the discussion at hand, but are you suggesting that you could perform the abovementioned water column experiment with a non-rigid tube of, say, flimsy plastic?

This is why we have weather.

Um, weather doesn't need a fan to get started.
Sure, your chimney will transport air if you put it in an updraft, but it won't create an updraft where none already exists. The air in the chimney won't travel faster than the air outside.

So why, exactly, do you need the chimney?
Why not just put a turbine in an updraft and be done with it?

As long as the Sun keeps heating the ground air, indirectly and directly, to be hotter than the air above it, the current will continue.

Yes, yes. Hot air is, all other things being equal, lighter than cool air. But the problem is that all other things are not equal.

This reminds me of when I tried to disabuse a good friend of me of the gambler's fallacy - he maintined that if you tossed a coins 6 times and got tails the first 5 times, the last time would be certain to be heads.
No matter what I said, he always came back to one fact that he considered irrefutable: All other things being equal, the coin should come up heads as often as tails.
What he failed to realize was that, as in this example, all other things are not equal.
posted by spazzm at 5:50 PM on November 25, 2006

spazzm, i'm certainly no expert, but your example sounds inapposite. a "flimsy" tube would equalize the pressure along its length by expanding or contracting; a "rigid" tube is essentially forcing an equalization in pressure between two very distant points; think of it as creating a new path-of-least-resistance, or like a wormhole. as the pressure at one point drops relative to the other, it creates a siphon force through the tube.

eb, is that correct?
posted by spiderwire at 7:07 PM on November 25, 2006

"This isn't really pertinent to the discussion at hand, but are you suggesting that you could perform the abovementioned water column experiment with a non-rigid tube of, say, flimsy plastic?"

If it's not too flimsy. I've done it with typical laboratory tubing.

Um, weather doesn't need a fan to get started. Sure, your chimney will transport air if you put it in an updraft, but it won't create an updraft where none already exists. The air in the chimney won't travel faster than the air outside. So why, exactly, do you need the chimney? Why not just put a turbine in an updraft and be done with it?"

No, but weather needs something to break what otherwise causes that thermocline to exist. It doesn't take much, that's why there's so much weather. That's why it would only take a fan to accomplish the same thing. Once the fan moves hot air to the same altitude where colder air is present, then the hot air will continue to rise. At that point you don't need the fan. You need a chimney structure to constrain the force of the fan upward, and you need it after the process becomes self-sustaining to prevent it from being dissipated by turbulence, crosswinds, whatever.

Spazzm, your gambler's fallacy invocation is interesting because in this case you are your friend, not me. I say that as kindly as possible although you're not making as much effort to avoid being insulting. At this point I don't even know what your objection is—that there's no such thing as convection? That the fact that ground-level air is usually hotter than upper-level air represents a thermodynamic instability? Well, of course not. You know both these things. I come back to the same fact over and over because I'm right.

In fact, and I'll try to phrase this in a way that's less insulting than your probability example and offer my own probability example. :) I wrote and put up on the web back in 1994 the first treatment of the Monty Hall Problem. It still exists, though it gets less traffic than it once did due to me changing hosting and never bothering to inform all the pages which link to its old location. Anyway, over the years I corresponded with many people who were skeptics concerning the (correct) solution I present to the problem. How people are confused about it is a very interesting topic in itself. But one thing that was especially interesting to me is that so many people failed to look to some authorities even though I repeatedly asked them to do so. We'd argue, I'd present my various arguments, each honed through years of use, and when that didn't work, there wasn't anywhere else to go. We disagreed on something that I simply wasn't going to resolve myself. On the other hand, the skeptic could easily email five or ten mathematicians at universities and ask them what the answer is. They don't need to explain it, just tell him so he can find the direction to go. I think that's where you are in this discussion.

You could say the same to me except for two things. One, we were not on equal footing from the outset, as I was relating something that an authority in the subject had already put forward. You don't really have any reason to disbelieve me on that. That's not much, but given that you're just going on your own reasoning, it's something. Two, the other person with whom I was arguing has conceded my assertions. That's not much by itself, either, but it adds further to the asymmetry. So I think the onus is on you to ask someone who knows to settle the matter. Or, alternatively, engage in the discussion with the assumption that you are misunderstanding something and wish to start over from the beginning to correct it.
posted by Ethereal Bligh at 1:02 AM on November 26, 2006

"eb, is that correct?"

I probably already answered this, but yes and no. Depends on the material. But let's assume the material was very elastic. What would happen?

I don't know. This would be a good experiment with something extremely flimsy, like cellophane, that would answer the question clearly. I'm of two minds. On the one hand, I know that, as I said, buoyancy works with pressure from below, not at all the sides. I'm certain that along the length where the column of water exists there will be no constriction of the tube. On the other hand, I just want to say that above the water, where there's a relative near-vacuum, it will compress (or collapse in the case of something very flimsy). And if that is the case, then just conducting the experiment would be difficult with a very flimsy material because I think it'd be easy to get worse and worse kinks if it's not done perfectly.

But I just don't know. I don't know if it makes sense to say that there's pressure independent of the atmospheric pressure due to gravity. I keep thinking that obviously there is. And then I realize that it's the same intuition telling me this that would have denied how buoyancy really works in the first place and would have expected the water to behave other than how it does. So I don't trust it.

I actually spent some time, years ago, discussing the counter-intuitive nature of buoyancy and fluid-dynamics with a couple of physics grad student friends of mine. (If it matters, one astro and one atmospheric. The latter you'd expect to be most qualified.) We ended up going in circles trying to deal with the gas laws in this. We decided that, in the experiment I mention above for example, you'd have stuff happening in the gas law domain near the interface of the water and the tube above it. We started thinking of more abstracted and clean systems and found that we got a bit more confused than we already were. Bottom line was that nature doesn't abhor a vacuum, as a general rule, but that only gets you so far. Other things happen, too. And, of course, being serious students pursuing their academic careers, they had more important things to do, unlike me. :)
posted by Ethereal Bligh at 1:28 AM on November 26, 2006

I wrote and put up on the web back in 1994 the first treatment of the Monty Hall Problem.

No, you did not. The problem (and its solution) has been known since the 19th century, and known under the name "Monty Hall" since at least 1989. Perhaps you meant to say that you were the first to put a treatment of the Monty Hall problem on the web?

Your Monty Hall analogy is apt since, like the Gambler's Fallacy, there are plenty of academic works that can be referenced and experiments that can be carried out to prove which theory is right.

As for your thermodynamic theories, I suggest you prove it by building it, or presenting some equations that that substantiate your claims.

Until then, I remain skeptical.
posted by spazzm at 12:52 AM on November 28, 2006

"Perhaps you meant to say that you were the first to put a treatment of the Monty Hall problem on the web?"

Of course that's what I meant.

Email a fucking physicist. Christ.
posted by Ethereal Bligh at 1:10 AM on November 28, 2006

Email a fucking physicist.

There's no need for that kind of language.

Since you're making the claim here, doesn't the burden of proof rest on you?
posted by spazzm at 3:24 AM on November 28, 2006

I'm certain that along the length where the column of water exists there will be no constriction of the tube.

Okay, I want this to be crystal clear:
Let's say I did the following:
1. Create a tube, 30 cm (12 inches) in length, 5 cm (2 inches) in diameter, from a thin, flexible plastic - same thickness and flexibility as supermarket shopping bags.
2. Submerege the tube vertically in a basin of ordinary water at STP so that only the top 5 cm (2 inches) are above water.
3. Seal the top end of the tube.
4. Raise the tube up so that only the bottom 5 cm (2 inches) are submerged.

Are you claiming that I would see a column of water inside the tube, roughly 5 cm (2 inches) in diameter, extending over the surface of the rest of the basin?
posted by spazzm at 5:03 AM on November 28, 2006

I've sworn off metafilter for awhile (I need to get some work done!) but I wanted to come back and make a quick explanation of the solar chimney, because it seems that there's still argument going on.

Firstly, it's impractical to build a flexible structure on the scale that's being considered for solar chimneys. But let's suppose we could do it. Imagine a tube that's flexible enough that the pressure inside the tube is the same as the pressure outside the tube. Note that this can't actually be guaranteed (especially considering as we're imagining flow along the tube), but it seems like a scenario worth considering. Now we get the chimney started by sucking warm air up from the ground, until the whole tube has air that's warmer than the surrounding air at its level. The only job of the tube is to keep this warm air from dispersing, maintaining a column.

The ideal gas law can be written as:
Pressure = Boltzmann's constant x Density x Temperature.
Since at any given height the pressures are equal and the temperature inside is greater than the temperature outside; it follows that the density inside is less than the density outside. Thus, the column of air inside the tube has less mass (and weighs less) than an equivalent column outside the tube. The system will move to a lower energy state if the warm, light air inside the tube rises and is replaced by colder, surrounding air at the base. As long as the ground can warm the air at the base fast enough, the process will continue.

This system would definitely work in principle. There are several towers of this nature being constructed, except for the addition of a large collector area at the base ---which provides more, warmer air and makes the system more stable and practical. One thing that I find interesting is that if there's no collector on the base of the tower, I can't think of any reason why the chimney wouldn't be just as effective as a downdraft tower (i.e. start it by sucking cold air down, and it will maintain a state where the tower holds colder, heavier air which sinks).
posted by Humanzee at 10:40 AM on November 28, 2006

"...extending over the surface of the rest of the basin?"

"Over" makes me wonder what you're describing, "above" would be correct. And the answer is "yes", but the flimsier the material, the more carefully you'd have to be about pulling the column of water upward.

And a [snip] on preview because Humanzee's comment should close the matter.
posted by Ethereal Bligh at 10:53 AM on November 28, 2006

Humanzee, don't you think that the hydrostatic pressure of the atmosphere is the dominant force here? It doesn't seem to me that the walls of the chimney need to be flexible for the chimney to work—I think they could be completely rigid. Imagine the state of the chimney if you've filled it from below entirely with the warm air. At every height above the thermocline, it will be under slightly less hydrostatic pressure than the atmosphere outside the chimney because, being warmer, it is less dense. The entire column of air inside the chimney will be under less pressure than the air outside it. Thus air from outside the chimney will be forced into it. Because the air isn't trapped and leaves the chimney, then the pressure difference remains the same, air continues to be forced into the bottom and to rise up the chimney, and so on.
posted by Ethereal Bligh at 11:07 AM on November 28, 2006

"Over" makes me wonder what you're describing, "above" would be correct. And the answer is "yes", but the flimsier the material, the more carefully you'd have to be about pulling the column of water upward.

If you really believe that, there's nothing I can do to help you. I invite you to try it - I think you will find that the plastic tube collapses, no matter how careful you are.

Since at any given height the pressures are equal...

The pressure inside the top must be greater than the pressure outside the top, otherwise no air will flow out. Likewise the pressure inside the bottom must be lower than the pressure outside the bottom, or no air will flow in.

I'm not disputing the fact that warm air rises - I'm skeptical that the tube is necessary to start or maintain the process, and that the tube could start the process where there isn't already a natural updraft.

At every height above the thermocline, it will be under slightly less hydrostatic pressure than the atmosphere outside the chimney because, being warmer, it is less dense.

Have you ever considered what it is that creates a thermocline? There are other factors than temperature that specifies the density of air - moisture content for example.

A thermocline can exist between moist, warm air at the bottom and dry, cool air at the top because the moist air is denser than the dry air, despite the temperature difference.

As soon as the lower air is less dense than the top air, it will rise - with or without a tube.
posted by spazzm at 12:44 PM on November 28, 2006

Sadly there's a gaping hole in my knowledge of physics where fluid flow ought to be (somehow, I never wound up taking a class that addressed it in detail). Therefore, I can't claim to know exactly what the equations governing a real solar chimney would be: I was just pointing out that even if internal and external pressure was essentially equal along the length of the chimney, it would still work. To be realistic, in treating this problem, you'd have to describe radiative heat loss, interaction of the air flow with the chimney walls, the tendancy for the air to expand as it rises and decreases in pressure, the interaction with the air temperature and the ground, and all sorts of other stuff. My gut feeling is that buoyancy (due to differences in density) drives the system, and pressure differentials would be used to extract energy from it for human use. That's just a gut reaction though, I haven't worked through any equations to make sure.

I do know that the actual mechanics would be complicated. To give a for instance: if the tower was really super tall, the pressure at the top inside would actually be greater than the pressure outside. You'd be taking high-pressure ground air and raising it up quickly high into the atmosphere where the ambient pressure is lower. Not only that, but the whole point of this system is to stick a turbine on the tower and extract power ---so there's a huge pressure differential across the turbine (which I think would have to be at the top). I'm guessing that the pressure at the bottom would be roughly equal ---but again, that's just a guess.
posted by Humanzee at 12:50 PM on November 28, 2006

There are several towers of this nature being constructed, except for the addition of a large collector area at the base ---which provides more, warmer air and makes the system more stable and practical.

The "collector" is actually greenhouse, designed to heat the air inside more than the surrounding air, thereby creating a temperature difference that forces the air under the collector to rise relative to the unheated air.

Ethereal Bligh is proposing to utilize hydrostatic pressure and thermoclines without a temperature difference at ground level - a different principle.
posted by spazzm at 12:57 PM on November 28, 2006

...if the tower was really super tall...

Is that a customary super tall or a metric super tall?

Seriously, though:

You'd be taking high-pressure ground air and raising it up quickly high into the atmosphere where the ambient pressure is lower.

Ground air is at high pressure because the atmosphere is on top of it. If you take it up to a higher altitude (without confining it to an airtight container) you'll discover that it is no longer at high pressure. You'll also discover that you've expended work by raising the air against the force of gravity.
posted by spazzm at 1:34 PM on November 28, 2006

Ugh.

I initially thought that was what he meant too, but I'm now convinced that isn't true. He's talking about the ground heating up the air at ground level, resulting in convection.

Assuming constant temperature gas, the pressure gradient has a characteristic length scale of:
boltzmann's constant x temperature in Kelvin / (acceleration of gravity x mass of molecule).
By characteristic length, I mean an e-folding length:
Pressure = P_ground * exp(- height / characteristic length)

Assuming the ideal gas is pure diatomic nitrogen at 100 degrees F, the pressure has a characteristic length of just over nine kilometers. For a 400 m tall tower, that means the gas at the top will decrease in pressure by about 4% from ground level pressure ---neglecting any compression from the boyant force pushing the gas into a turbine. So that's what I meant by "super" tall: a significan fraction of the characteristic length associated with the pressure gradient; which happens to be much taller than most man-made structures.

One can look at the above formula and see that the pressure at the top of a uniform column of hot gas is greater than the pressure at the top of a uniform column of cold gas, even if they're both stationary. If the temparature varies along the length of the column, the pressure will be intermediate. If the hot gas is being pushed up from below, it may not have time to equilibrate, and may be at an even higher pressure than the static case (although again, I am not familiar enough with fluid flow to work through equations for this case). Crunching numbers seems to indicate that the pressure difference would be small on the top of static columns of gas, and that therefore buoyancy has to be what drives the system.
posted by Humanzee at 2:33 PM on November 28, 2006

So are we talking about a solar updraft tower or EB's tower?

I still don't see why the thermodynamic explanation (furnace -> condenser) doesn't work.
posted by spiderwire at 2:59 PM on November 28, 2006

Humanzee, I came upon the Wikipedia "Solar Updraft Tower" independently and immediately went to the talk page -- did you guys see this? They even had to take it to mediation.

Surely there is a conspiracy afoot.
posted by spiderwire at 3:09 PM on November 28, 2006

He's talking about the ground heating up the air at ground level, resulting in convection.

Again, I completely agree that when ground-level air is heated it will rise.

What I'm skeptical about is that the tube is the only necessary part to maintain the process - after all, convection happens all the time. If convection is happening, what role does the tube play? How is the tube creating and maintaining convection that would not happen anyway?
posted by spazzm at 3:22 PM on November 28, 2006

OK, upon further consideration: EB is correct, spazz, you are, unfortunately, wrong. Your argument would be true if the atmosphere were in thermodynamic equilibrium, which it's not. What EB is proposing is essentially a bridging of two thermoclines, taking advantage of the fact that an inversion generally keep them separate.

Assuming constant temperature gas, the pressure gradient

Ding! The atmospheric pressure gradient isn't constant.
posted by spiderwire at 3:25 PM on November 28, 2006

*keeps
posted by spiderwire at 3:25 PM on November 28, 2006

spazzm: capping inversion
posted by spiderwire at 3:27 PM on November 28, 2006

Actually, the wikipedia inversion article may make more sense:

A warmer air mass moving over a cooler one can "shut off" any convection which may be present in the cooler air mass. This is known as a capping inversion. However, if this cap is broken, either by extreme convection overcoming the cap, or by the lifting effect of a front or a mountain range, the sudden release of bottled-up convective energy---like the bursting of a balloon---can result in severe thunderstorms. Such capping inversions typically precede the development of tornadoes in the midwestern United States. In this instance, the "cooler" layer is actually quite warm, but is still more dense and usually cooler than the lower part of the inversion layer capping it.

posted by spiderwire at 3:29 PM on November 28, 2006

Your argument would be true if the atmosphere were in thermodynamic equilibrium, which it's not.

I'm not saying air won't flow through the tube, I'm saying it won't flow faster or longer than outside the tube.

In this instance, the "cooler" layer is actually quite warm, but is still more dense and usually cooler than the lower part of the inversion layer capping it.

So you have dense air at the bottom, and less dense air above it. The 'capping' is not a cap in the sense of a bottle cap, but an end to the rise of convection in the lower, cold layer. It stops rising because it encounters a layer of less dense air, and buoyancy no longer forces it upwards.
Putting a tube through such an inversion layer won't change that fact.
posted by spazzm at 3:53 PM on November 28, 2006

It's called an inversion because it's a reversal of the expected temperature gradient.

Not only is there no macro-level equilibrium (that's why there's inversion layers which can be 'popped,' releasing violent thunderstorms), there's even less micro-level equilibrium (hence the existence of, e.g., microbursts).

That's why we have weather in the first place. The atmosphere is naturally unstable, meaning that displaced air tends to accelerate as it tries to return to equilibrium. We measure the potential for severe weather directly in terms of potential energy created by instability. (seriously, read that link)

To specifically address the topic at hand, the theory, as I understand it, is that you'd create a stable convection between two points -- depending the degree to which you're about to stabilize the convection tube. The reason this would be more useful in a vertical tube, I would suppose, is that there's much more vertical instability in the atmosphere than there is horizontal.
posted by spiderwire at 4:25 PM on November 28, 2006

That's why we have weather in the first place.

I don't dispute that at all.

I'm disputing the claim that the tube would create or increase the rate of convection.

Let's try a thought experiment:
There is an inversion layer at 400 meters.
Below the layer the air is cool and dense. The air above the layer is warmer but, and this is crucial, less dense, according to the WP article. No up or down drafts are present through the inversion layer.

Now you put a 500 meter long tube vertically in the atmosphere. The bottom end is in the cool, dense air below the inversion layer and the top end is in the warm, thin air above the inversion layer.

Will air automatically flow through the tube?
I think we all agree that the answer is no.

So the next step in the experiment is to blow (or suck) the warm, dense air from the bottom to the top, filling the tube.

Will that start a flow of air?

I say no, because:
The crucial component in buoyancy is density, not temperature. The warm air in the tube has a higher density than the surrounding, cool air (despite the temperature difference). Therefore the column of air in the tube will weigh more than an equivalent column outside the tube, and the air in the tube will actually sink, not rise - undoing the work done in order to get it up there in the first place.

To summarise my point:
Warm air can, under the right conditions, be denser (and thus heavier) than cool air. When this is the case, warm air won't be forced up by buoyancy.
posted by spazzm at 4:50 PM on November 28, 2006

spazzm, you should really read that link. although it may seem counterintuitive to think of the atmosphere as differentiated, it is the case. consider that an inversion layer is "capped" only at the bottom, or that you could conceivably has multiple inversion layers piled on top of one another.

or, alternatively, think of how thunderstorms "break." the reason why the instability index is defined in terms of potential energy, as i understand it, is that two pockets of air are in disequilibrium -- a storm is essentially a violent equalization between the two pockets, and the violence of the storm is directly related to potential-energy difference between them.

or, consider why there would be two separate "layers" of atmospheric density in the first place -- clearly, there must be something in the system creating discontinuities in the pressure gradient.

i'd concede that there's an open question of whether a "tube" creating a stable convection would pierce the inversion cap and create a stable equalization, but your objection is still inapposite. the question is merely whether you could create a sufficiently stable (non-entropic) bridge, and i'd imagine (based on my limited knowledge of meteorology and fluid dynamics) that the relevant questions would be moisture, insulation, and the rigidity of the tube.
posted by spiderwire at 5:10 PM on November 28, 2006

also, warm air is denser than cool air.
posted by spiderwire at 5:11 PM on November 28, 2006

or rather, in an atmosphere, it is. adiabatic cooling.
posted by spiderwire at 5:12 PM on November 28, 2006

also, warm air is denser than cool air.

Temperature is not the only thing that determines density, especially in an atmosphere.
posted by spazzm at 6:13 PM on November 28, 2006

or, consider why there would be two separate "layers" of atmospheric density in the first place -- clearly, there must be something in the system creating discontinuities in the pressure gradient.

Yeah - moisture.
posted by spazzm at 6:19 PM on November 28, 2006

Temperature is not the only thing that determines density, especially in an atmosphere.

perhaps you should read the comment directly beneath that one.

regardless, you said:

Warm air can, under the right conditions, be denser (and thus heavier) than cool air.

which is nonsense. in fact, this is the very thing that causes convection to happen in the first place. i just wanted to clarify that i wasn't talking about the ideal gas law -- which appears to be exactly what you assumed -- but apparently you decided to comment before reading.

Yeah - moisture.

wrong again. like i said, i'm not an expert in fluid dynamics, but clearly, neither are you. if you were, not only would you have actually defended all the crap you spouted upthread, you wouldn't give such an asinine answer to what's an extraordinarily difficult question.

properly stated, the question is not 'moisture' but viscosity, which in the atmosphere is the product of not just humidity, but the heat conductivity of air, the terrain beneath it, and even gravity. regardless, the issue is still whether the entropy (turbulence) could or couldn't be overcome by a "tube" creating laminar flow between the two pockets. (in other words, there is a reason why boundaries are treated specially in fluid dynamics.) that's what a proper response to EB's hypothesis would discuss.

you, however, clearly have no idea what you're talking about, which means you should have dropped the topic long ago. whether you're oversimplifying meteorology with regards to pressure, moisture, or whatever else, you probably won't get away with patronizing the rest of us with facially ridiculous 'thought experiments.'

i'm done.
posted by spiderwire at 7:34 PM on November 28, 2006

amazingly, EB's first comment close to what i just said, except for the bit about the thermoclines, but that's at least pointing in the right direction.

i don't know how this thread has gone on so long with so little in dispute (and after such a ridiculous derail), but at least i learned some interesting things about fluid dynamics. it's sad that spazzm couldn't be encouraged to do the same rather than look like a nitwit.
posted by spiderwire at 7:49 PM on November 28, 2006

which is nonsense.*

* gah. nonsense in that warm air being denser is the rule, not the exception: increased pressure = increased temperature, blah blah. regardless, wasn't relevant to begin with.
posted by spiderwire at 7:51 PM on November 28, 2006

it's sad that spazzm couldn't be encouraged to do the same rather than look like a nitwit.

I don't see the need for nastiness.

nonsense in that warm air being denser is the rule, not the exception

I implied no such thing.
The statement that warm air is denser is from the WP article you linked.
posted by spazzm at 8:32 PM on November 28, 2006

And applies when there is an inversion layer.
posted by spazzm at 8:33 PM on November 28, 2006

The statement that warm air is denser is from the WP article you linked.

i misread your parenthetical. that was my bad.

see how easy that was? hence, what follows:

I don't see the need for nastiness.

frankly, dude, i came into this thread after you did and had to spend a while catching up on my physics before it became painfully apparent that you were wrong.

but (1) i did my reading in less time than it took you to make a strawman objection to EB ("build your own tower"?), so it's not asking a lot of you, (2) from the very start EB's been on-point and you haven't, and (3) he labored to explain everything to you, yet you've been nonresponsive. i even gave you links.

sadly for you, 'nastiness' in response to intellectual laziness is fair play.

if you're content to needlessly snipe at people, you shouldn't be surprised when they mock you for not doing the remedial reading. if you can't be bothered to admit when you're wrong, cut your losses, take your toys, and go home.
posted by spiderwire at 9:23 PM on November 28, 2006

sadly for you, 'nastiness' in response to intellectual laziness is fair play.

I've outlined a repeatable experiment to test EB's chimney theory.
If you think that is intellectual laziness, fine, but as I've said before - if you're making a claim, the burden of proof is on you.
posted by spazzm at 9:40 PM on November 28, 2006

Or to put it another way:
Calling me a twit won't change the laws of physics.
posted by spazzm at 9:52 PM on November 28, 2006

"If you really believe that, there's nothing I can do to help you. I invite you to try it - I think you will find that the plastic tube collapses, no matter how careful you are."

No. This is an example, among others, of where you think your intuitive understanding of the physics involved is correct when, in fact, you badly misunderstand it. I don't know why I bother, but: with hydrostatic pressure, the only two variables which matter are the diameter of the opening and the height of the liquid above that opening. The force is downward. You can raise a tube of liquid as we've described using a flimsy material and it won't "collapse" because there's no hydrostatic pressure acting on its sides. That's how hydrostatic pressure works. It's counterintuitive, but basic physics. If you can't get this right, we shouldn't even be attempting to converse about this kind of stuff.
posted by Ethereal Bligh at 10:46 PM on November 28, 2006

I've outlined a repeatable experiment to test EB's chimney theory.
If you think that is intellectual laziness, fine, but as I've said before - if you're making a claim, the burden of proof is on you.

He's proposing a 10km tall tower built from some material that can withstand the shearforce yet remain sufficiently rigid to create the necessary flow conditions. And you tell him "dur, go build it." That's not a response, that's a strawman. And such a transparently dumb strawman that it's pretty insulting considering that EB was responding to you respectfully.

EB explained to you all the reasons why it might work and your only substantive responses were high school physics -- and mostly wrong high school physics at that. You still have yet to make a substantive argument. I bothered to go out and try to explain to you the meterological and fluid-dynamics issues here as I understand them, and yet you still can't wrap your head around what an inversion layer is.

I already have a whole page of responses prepped to EB's argument that i'm ready with if he's interested -- apparently you don't care. If so, bow out.

Or to put it another way:
Calling me a twit won't change the laws of physics.

I didn't want to change the laws of physics, I wanted you to consider, you know, learning them. Go read EB's first post. Start there. He did it like 3 or four times and you still haven't wrapped your head around it. When you get back and you have the first clue what you're talking about, we can discuss the problems with constructing a rigid tube to create a self-sustaining laminar flow cycle between two atmospheric pressure cells.

Seriously man, learn when to cut your losses.
posted by spiderwire at 10:48 PM on November 28, 2006

actually, EB, I think that problem in your theory is that there would be problems with condensation and with turbulence disrupting the constant airflow you'd need to get a sustainable cycle. also, a flexible tower might shed too much of the potential energy, while the tensile strength required for a rigid tower would be astronomical. however if there was a way to heat/cool the air uniformly and remove the moisture, maybe by wicking, using metal 'whiskers' with high heat conductivity to pull water out of the inside air and let it drip down the sides of the tube. who knows.

it seems to me that, if you managed all that, you would create a sufficiently fluid conduit (given the fluid laws near boundaries) between the two air pockets that you would be able to create a relatively stable laminar flow. if the vicosity couldn't be removed from the system, i imagine that it would either stall, burp (build up pressure and explode), or not be sufficiently contained, by insulation or rigidity or temperature, and merely radiate off its potential energy that way.
posted by spiderwire at 10:56 PM on November 28, 2006

"The "collector" is actually greenhouse, designed to heat the air inside more than the surrounding air, thereby creating a temperature difference that forces the air under the collector to rise relative to the unheated air.

Ethereal Bligh is proposing to utilize hydrostatic pressure and thermoclines without a temperature difference at ground level - a different principle."

All the collector does is magnify the effect tremendously. If you accept the principle behind what is happening, then you should note that both the case with the collector and in my case, the ground level air is warmer than the air surrounding the top of the tower. The reason one works is the reason the other would work. The reason my collector-less tower needs a fan to start is it needs to first overcome that energy barrier, not unlike a siphon.

Spiderwire: with all due respect, I'm pretty fatigued with this discussion. Not only is it a digression from the thread, but it really isn't that pertinent to the point I was initially making! But on preview: I have no idea what would happen in actual practice. As you point out, there's lots more variables that complicate things. This was always intended to be a gedankenexperiment, not a blueprint. :)
posted by Ethereal Bligh at 11:02 PM on November 28, 2006

I don't know why I bother, but: with hydrostatic pressure, the only two variables which matter are the diameter of the opening and the height of the liquid above that opening. The force is downward. You can raise a tube of liquid as we've described using a flimsy material and it won't "collapse" because there's no hydrostatic pressure acting on its sides.

Did you try it?
Obviously not, or you would discover that the tube is collapsed by the air pressure over the surface of the water in the basin.


He's proposing a 10km tall tower built from some material that can withstand the shearforce yet remain sufficiently rigid to create the necessary flow conditions. And you tell him "dur, go build it." That's not a response, that's a strawman

No, that's not a strawman - that's how science is done: By checking the facts. The facts, in the case of physics, is physical reality. If your theory can't be checked by an experiment, it's not a very good theory.

Which is why I'm skeptical.

I guess considering skepticism an insult is perfectly acceptable for some.

If you accept the principle behind what is happening, then you should note that both the case with the collector and in my case, the ground level air is warmer than the air surrounding the top of the tower.

Yes. That is why it rises - with or without the tube - provided it is less dense than the air above it.
If it is denser than the air above it, it will not rise.

Buoyancy relies on differences in density, not temperature.
This is why ice floats - it is less dense than liquid water, despite being colder. The same principle holds for gases.
posted by spazzm at 1:48 AM on November 29, 2006

All the collector does is magnify the effect tremendously.

Actually, the "collector" heats the air in the same way as a greenhouse - heating the air underneath it by reducing the amount of heat reflected away.
The heated air expands, becomse less dense and rises (buoyancy). Where can it go when it rises? Only up the chimney, of course.

Your chimney, on the other hand, contains no mechanism for making the air directly under the pipe less dense than the air next to it, so buoyancy won't force it upwards.
So if there already is an updraft, it will pass equally through the tube and around it.

If there is no updraft, that means the ground level air is denser than the air above it. Raising it by means of a fan won't change that; When the fan stops, the dense air will simply sink back down to ground level.
posted by spazzm at 2:03 AM on November 29, 2006

"Obviously not, or you would discover that the tube is collapsed by the air pressure over the surface of the water in the basin."

You seem to misunderstand this experiment. The tube is submerged at its outset. It is thus filled with water. You hold the tube from its top, where it's sealed, and raise it out of the water. The tube won't collapse—it's filled with water. You can raise that column of water to a height of 33.9 feet, if you do the experiment at sea level, and then it will rise no farther. Above that the tube will be partial vacuum. It doesn't matter whether the sides of the tube are rigid or not. I performed the experiment myself with laboratory polyurethane tubing about 1/8 inch thick, which was quite flexible. A key idea of the principle demonstrated by the experiment is that hydrostatic force acts downward (and an opposing force, therefore, upward) and not at the sides. If there were a force at the sides, then you could keep pulling the water up to the top of the atmosphere. And you can't. There may be some forces acting on the sides that are relevant under some experimental conditions, but the overwhelming force is the hydrostatic pressure of the atmosphere which exerts a downward force.

You haven't even performed the classic experiment, nor even studied hydrostatic pressure at university as far as I can tell and yet you're smugly telling me, who has done these things, how the modified experiment would conclude. If you don't understand the principle involved, then you're not in a position to make predictions.

"If there is no updraft, that means the ground level air is denser than the air above it."

It may be more dense than air directly above it, but it's not more dense than the air at the top of the tower. You seem to be assuming that there is convection everywhere where convection could exist. But you should already know that it simply doesn't work that way. There's almost always one sort of an energy hump or another that a convection current has to overcome to get started. Why does the hot liquid go up where it does and why does the cool liquid fall down where it does and not vice-versa? Why is there a convection current at all and not a slow diffusion of clumps of hot molecules upward and clumps of cold molecules downward?

As mentioned above, part of what makes weather is that we have this system where the Sun is pumping energy into the air at ground level, as well as evaporating surface water into the air, while there's colder air above it. Convection is one of the structures that "want" to exist to put the system into equilibrium, but it doesn't happen everywhere at once. It happens where there are local conditions that are extreme relative to the global conditions. It might be an updraft from a mountain. It might be an updraft from air heated over a city. And it might be an updraft created by a fan. But in all these cases there's a distinction between the energy needed to get it started and the energy needed to sustain it.

It takes more energy to start it than it does to sustain it for obvious reasons (inertia, for one). In the chimney as I've described it you'll have convection acting by itself once the system is started. Once you've displaced the cold air out of the chimney with the fan, replacing it with the warm air from below, then all that warm air will continue flowing upward itself and more warm air from below will replace it. It may not be that great of a flow and the pressure gradient not that steep. Thus the need for the chimney structure to protect it from being disrupted by winds and becoming disorganized.

As far as I can tell, you are under two serious misconceptions. The first is demonstrated in your objections to the classic hydrostatic pressure experiment and a flimsy material. You seem to be thinking that the dominant forces are gas law forces and not hydrostatic pressure. You are then applying this misconception to the chimney argument. The second is that you seem to think that anywhere convection could occur it will occur and thus if there's not already a convection current, the chimney wouldn't create one that is self-sustaining. But you know after just a moment's reflection that there's far more places where a convection current could exist, but don't, than where they do. In a small tub of water heated from below there's places which aren't involved in the current. What makes an upward, convection-driven current appear instead of a downward current? Why one place and not another? The answer: some local extreme variation. It might be that the heating is particularly large locally. Or the cooling above particularly large locally. Or there may be inertial motion favoring one direction. Once the current starts flowing, it is acting as an energy transfer mechanism for the larger system and the local forces which gave rise to it are dwarfed.
posted by Ethereal Bligh at 4:55 AM on November 29, 2006

The tube is submerged at its outset. It is thus filled with water. You hold the tube from its top, where it's sealed, and raise it out of the water. The tube won't collapse—it's filled with water. [...] It doesn't matter whether the sides of the tube are rigid or not. I performed the experiment myself with laboratory polyurethane tubing about 1/8 inch thick, which was quite flexible.

In my outline of the experiment I specified plastic of the "same thickness and flexibility as supermarket shopping bags" and a tube diameter of 5 cm (2 inches). The 1/8 inch (over 3 mm) thick tubing you used is quite thick enough to withstand the difference in atmospheric pressure and the (lower) pressure inside the tube.

I urge you to do the experiment I outlined.

If you don't have a supermarket shopping bag handy, try something else - plastic wrap or a condom should do the trick.

You will find that when the plastic cannot withstand the atmospheric pressure, the tube will collapse and you cannot raise any column of water.

It may be more dense than air directly above it, but it's not more dense than the air at the top of the tower.

If there is dense air at the top of the tower, won't it be denser than the air below it at some point? And then, what's keeping buoyancy from equalizing the density difference?

The forces you suggest that hinder this equalization in the tub would work in the atmosphere, but they would work equally well in the tube as outside it - anything else amounts to special pleading.

Inversion layers, for example, are dense air under less dense air - so they won't help the chimney.

But, again, the ultimate way for you to prove your theory and convince this skeptic is to do the experiment.
posted by spazzm at 1:31 PM on November 29, 2006

You haven't even performed the classic experiment, nor even studied hydrostatic pressure at university as far as I can tell and yet you're smugly telling me, who has done these things, how the modified experiment would conclude.

I have performed both the classic and the modified experiment.
I'm not telling you how it would conclude, I'm telling you how it did conclude, and how it will conclude when you (or anyone else) performs it. If you think that is smug, then fine.

Now, please do the experiment.
posted by spazzm at 1:37 PM on November 29, 2006

The force is downward. You can raise a tube of liquid as we've described using a flimsy material and it won't "collapse" because there's no hydrostatic pressure acting on its sides. That's how hydrostatic pressure works. It's counterintuitive, but basic physics. If you can't get this right, we shouldn't even be attempting to converse about this kind of stuff.


A key idea of the principle demonstrated by the experiment is that hydrostatic force acts downward (and an opposing force, therefore, upward) and not at the sides. If there were a force at the sides, then you could keep pulling the water up to the top of the atmosphere. And you can't. There may be some forces acting on the sides that are relevant under some experimental conditions, but the overwhelming force is the hydrostatic pressure of the atmosphere which exerts a downward force. (emphasis mine)

Maybe I have misunderstood basic physics. Maybe you are right that the hydrostatic pressure only exerts a downward force.
But how do you explain this:

Pressure is not really a vector even though it looks like it in the sketches. The arrows indicate the direction of the force that the pressure would exert on a surface it is contact with.
[...]
Pressure can not exert any force parallel to the surface in which it is contact.

* The pressure at a given depth is independent of direction -- it is the same in all directions. This is another statement of the fact that pressure is not a vector and thus has no direction associated with it when it is not in contact with some surface.

* The pressure on a submerged object is always perpendicular to the surface at each point on the surface.
[...]

posted by spazzm at 2:05 PM on November 29, 2006

But, again, the ultimate way for you to prove your theory and convince this skeptic is to do the experiment.

because i have not in fact tested special relativity, i do not believe that it exists.

Inversion layers, for example, are dense air under less dense air - so they won't help the chimney.

brrrzzzt. wrong. exactly the opposite, in fact.

Maybe I have misunderstood basic physics. Maybe you are right that the hydrostatic pressure only exerts a downward force.

yes and yes.

it seems apparent from your tone and argument selection that you're on some level aware of how badly EB just owned you. so there is hope.
posted by spiderwire at 3:08 PM on November 29, 2006

also, you may note in that last link that none of the experiments were conducted using condoms, as you propose. there's a reason for that (hint: EB cited it. twice.)

ponder that one for a bit, while i try not to.
posted by spiderwire at 3:11 PM on November 29, 2006

"I have performed both the classic and the modified experiment.
I'm not telling you how it would conclude, I'm telling you how it did conclude, and how it will conclude when you (or anyone else) performs it. If you think that is smug, then fine.

Now, please do the experiment."

In that case I'll withdraw my assertion and perform the experiment myself when I have the materials.

This is still incidental to the chimney and you remain the only person among several who is skeptical.
posted by Ethereal Bligh at 10:37 PM on November 29, 2006

because i have not in fact tested special relativity, i do not believe that it exists.

Relativity has been tested numerous times, by numerous independent experimenters and each time it has been passed. I can't see how that is similar to an untested idea proposed in an internet forum.

>>Inversion layers, for example, are dense air under less dense air - so they won't help the chimney.

brrrzzzt. wrong. exactly the opposite, in fact.

From the WP page you yourself quoted earlier (emphasis mine):

In this instance, the "cooler" layer is actually quite warm, but is still more dense and usually cooler than the lower part of the inversion layer capping it.


Ethereal Bligh:
In that case I'll withdraw my assertion and perform the experiment myself when I have the materials.

Thank you. You are, unlike some I could mention, showing a true scientific mindset.


This is still incidental to the chimney and you remain the only person among several who is skeptical.

Maybe it is incidental, but it will at least test our understanding of pressure and dynamics, which is what this debate is about.

While it is true that I'm the only skeptic still left in the thread, science is not determined by democratic process.
posted by spazzm at 11:21 PM on November 29, 2006

"While it is true that I'm the only skeptic still left in the thread, science is not determined by democratic process."

Actually, to an important degree, it is. Peer review plays as important a role as the scientific method.
posted by Ethereal Bligh at 4:17 AM on November 30, 2006

In this instance, the "cooler" layer is actually quite warm, but is still more dense and usually cooler than the lower part of the inversion layer capping it.

That excerpt is talking about the botton of a capping inversion, not the difference between the inversion and the boundary layer.
posted by spiderwire at 6:19 AM on November 30, 2006

Actually, to an important degree, it is. Peer review plays as important a role as the scientific method.

I should have been more specific: The laws of nature are not decided by majority vote.

>>Inversion layers, for example, are dense air under less dense air - so they won't help the chimney.

brrrzzzt. wrong. exactly the opposite, in fact

From the inversion link you also posted earlier:
Under certain conditions, the normal vertical temperature gradient is inverted such that the air is colder near the surface of the Earth. This can occur when, for example, a warmer, less dense air mass moves over a cooler, more dense air mass. (emphasis mine)
posted by spazzm at 11:49 AM on November 30, 2006

The laws of nature are not decided by majority vote.

nor by sticking your fingers in your air and singing.

From the inversion link you also posted earlier:

ok, look. read this really slowly, over and over, until you get it.

you said: inversion layers are dense under cool air. this is wrong. that is a possible form of a climactic inversion. (note how the sentence you cite says "for example".) i posted you a link to the National Weather Service that should help you understand the concept. in fact, i've posted it three time now, so i can only assume you're wilfully ignoring it, or you're just a twit.

you even cite language referring to a capping inversion, which is essentially the opposite of what you describe. an inversion is a variation in the expected pressure gradient in an otherwise homeostatic atmosphere like the one you (incorrectly) imagine exists. this misconception is critical to your inability to understand what the hell EB is talking about, and i'm frankly baffled as to how his explanation hasn't sunk in yet.

at any rate, since the these variations in the expected gradient are, in fact, critical to the operation of the chimney EB describes (in that they represent imbalances in the weather system that the hypothetical tube would take advantage of), then your assertion is not only "wrong" but "exactly the opposite."

seriously, you have no clue what you're talking about. drop. the. subject.
posted by spiderwire at 2:22 PM on November 30, 2006

dense under cool air this is wrong.

*less dense warm air under more dense cool air. this is wrong.

i totally mucked up that sentence
posted by spiderwire at 2:26 PM on November 30, 2006