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hudsonderek

wind tunnels producing elecricity?

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my understanding of how wind tunnels work is pretty limited, but I was thinking, if they don't recirculate the air, and simple vent it out the top, why not throw some wind generators aft of the air exhaust and produce some electricity for lighting the place and other electric items in the building itself? better yet, why not make the wind tunnels be powered by electric engines and create some form of perpetual motion;) I know that wouldn't really work with the technology we have today. but hell we have all this good energy going to waste.

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my understanding of how wind tunnels work is pretty limited, but I was thinking, if they don't recirculate the air, and simple vent it out the top, why not throw some wind generators aft of the air exhaust and produce some electricity for lighting the place and other electric items in the building itself? better yet, why not make the wind tunnels be powered by electric engines and create some form of perpetual motion;) I know that wouldn't really work with the technology we have today. but hell we have all this good energy going to waste.


You answered it yourself with you perpetual motion comment. Conservation of energy says it can't be more efficient than just getting juice from the grid. Since the fans are grid powered, and the generator is powered by the output of the fans, all you are really doing is adding a complicated and inefficient conversion step. For every watt you draw from your generator, the fans will have to draw more than one watt to maintain the same airspeed.

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The idea is not totally stupid. The perpetual motion bit is silly, and so is the comment about using electric motors, since pretty much all the well-known tunnels *are* electric. On the other hand, citing conservation of energy isn't going to answer everything, either, because in an open flow tunnel like SkyVenture Arizona, the exhaust out the top of the tunnel is still carrying quite a bit of kinetic energy that is essentially being lost into the atmosphere. The trick is harnessing this lost energy in such a way that it won't mess with the airflow through the flight chamber. If you just stick a couple of turbines attached to electric generators on the top, this will impede the airflow through the tunnel and require you to run the fans a lot harder to get the same airspeed, and due to friction and other losses, the extra energy into those fans will always be greater than the energy you can extract from those generators.

I suspect that the best way to make use of the kinetic energy in the exhaust wind would be to build some kind of aerodynamically efficient ducting to redirect the air back down around the side and into the bottom of the flight chamber again. Hang on... [:D]

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that's why I thought if you put the wind generators aft of the air exhaust then it would be fine, if you had it right a the top of the exhaust, it would build up back pressure and cause the engines to work harder, but if you put it far enough away from the exhaust tip, then any pressure build up could be released out of the side area between the exhaust tip and the wind generator, I know some wind generators function best at certain speeds and require governers as to not over speed, maybe the wind generated would be to fast. I agree running an alternator, or generator of some sort directly off of the engine which produces the air flow for the wind tunnel would be counter productive. but the airflow going out of the tunnel is pretty much being wasted.

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ok...how about this:

1) Set up a wind tunnel in Fort Collins, Colorado
2) Just west of Town. Dig a huge hole (reservoir) ...some farm property. Run a Large pipe up to Horsetooth reservoir .
3) place a generator inline with the pipe
4) Flow Water down the pipe durring the day (high demand for electricity) sell the electricity to the grid.
5) Nights, pump the water back up to the reservoir. (when one can buy electrity cheap durring non demand hours)
6) take the profits to reduce the cost of a recirculating tunnel.

Chuck

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Yes - I realize that the further away from the wind tunnel you place the turbine, the less impact you're likely to have on the airflow in the flight chamber, however, you're also capturing much less of the exhaust wind and therefore much less of the waste energy. I think that by the time you've moved the turbines far enough away, the energy yield from the turbines will be negligible. You're also talking about some very expensive plant. Let's assume that you do generate enough power to run your lighting and video equipment, POS terminal and such. At worst, this is going to save you perhaps a few hundred dollars per year. These turbines and generators you want to install are likely to add millions to the capital costs for construction of the system. If you spend a million dollars to save less than $1000 per year, it's going to take you at least 1000 years for the installation to pay for itself. I just can't see the wind tunnel lasting that long, and we haven't even considered the maintenance cost of the plant, yet, which I'm also fairly sure would outpace the power saving you might get.

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ok...how about this:

1) Set up a wind tunnel in Fort Collins, Colorado
2) Just west of Town. Dig a huge hole (reservoir) ...some farm property. Run a Large pipe up to Horsetooth reservoir .
3) place a generator inline with the pipe
4) Flow Water down the pipe durring the day (high demand for electricity) sell the electricity to the grid.
5) Nights, pump the water back up to the reservoir. (when one can buy electrity cheap durring non demand hours)
6) take the profits to reduce the cost of a recirculating tunnel.

Chuck



To what business are you trying to attract investors? A pumped storage hydro-electric generator or a sports related amusement? If you have many millions of dollars to spend, then by all means go ahead, but if you don't you're going to have to convince someone else to give you the money. The lack of focus will make it harder to attract investors in the first place. Those same investors will also ask the question of why they should be giving the power they generate to the wind tunnel on the cheap or even for free when they could sell it on the open market for a better price. Investors aren't likely to give you money to build something that doesn't give them a return on their investment. Those profits from the pumped storage hydro-electric generator belong to the investors and they're not likely to be interested in using them to subsidize your playing in the wind tunnel.

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Hey..

I have got an even better idea!... hows about this one....

We take a big bucket to the bottom of the ocean - then convert water to hydrogen/oxygen using electricity and use those gasses to lift the bucket to the surface... add a mechanism so that as the bucket rises we generate electricity to fuel this conversion process - and then use that electricity to generate more hydrogen etc... the byproduct gas we can then use to generate more electricity by burning it at the surface and bingo! - no problems!

B|


Bodyflight Bedford
www.bodyflight.co.uk

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Hey..

I have got an even better idea!... hows about this one....

We take a big bucket to the bottom of the ocean - then convert water to hydrogen/oxygen using electricity and use those gasses to lift the bucket to the surface... add a mechanism so that as the bucket rises we generate electricity to fuel this conversion process - and then use that electricity to generate more hydrogen etc... the byproduct gas we can then use to generate more electricity by burning it at the surface and bingo! - no problems!

B|


Ok but what if the bucket has a hole?:S

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dont like the idea (buy cheap...sell high) ? even to produce electricity ?



I don't have a problem with that concept at all. A great many people make their living by selling things for a higher price than that at which they acquired them, however I don't see the relevance of your comment.

My point is, if you want to build a power generation plant, then build one. If you want to build a vertical wind tunnel, go right ahead, but they're two separate businesses.

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Hey..

I have got an even better idea!... hows about this one....

We take a big bucket to the bottom of the ocean - then convert water to hydrogen/oxygen using electricity and use those gasses to lift the bucket to the surface... add a mechanism so that as the bucket rises we generate electricity to fuel this conversion process - and then use that electricity to generate more hydrogen etc... the byproduct gas we can then use to generate more electricity by burning it at the surface and bingo! - no problems!

B|



Okay, so the net gain from the hydrogen/oxygen production is going to be a very negitive #. I'd have to go put the numbers together, but I suspect that the ammount of power provided by the lift of the gasses would be a lot less than the power needed to break up all of that water.

I'm assuming that your going to use fuel cells at the surface to recombine the H2 and O2 to increase efficency,

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What if you just built a massive room/plenum chamber downstream from a hydro-electric dam and set the wind-tunnel on top of it.
You could drain the room at night.
As it filled with air during the day, it would force air out through the wind tunnel.
When you paused for lunch, you could drain the plenum chamber and repeat the process in the afternoon.
Nothing that a few hundred thousand tons of concrete couldn't solve!

Oh!
And you just might want to build it beside a fast-flowing major river.

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