wind generator?

[92sEgg]

Hello, im sure i'm not the first to think of this but i dont often see the idea being discussed. how does the idea of a fan(vertical/tower type) being used to build electricity up? I suppose theres a great deal of difference between aerodynamically efficient and not being so aerodynamically efficient.

depending on where its placed and how its designed of coarse, might this unit have the potential to power/charge anything?

im mostly on expressways...

i was thinking of placing it on the rearmost of my roof. having the blades pick up wind and spin a motor, acting as a generator.

[NeilBlanchard]

Hi,

This will always "cost" more energy than it gains. There is no such thing as a perpetual motion machine.

[theunchosen]

I agree with neil.

However. . .I had considered a possible proposition. instead of mounting it above or outside the the streamline of the car, why not place it somewhere the car has a drag issue that cannot be overcome. The first idea would be maybe a small 6 inch turbine mounted along the grill. Mounted in places the car is going to take a drag hit anyway.

I know you can't get a free lunch. . .but you might be able to recover some of your lost energy from drag(by causing drag where it generates electricity instead of on the surface of your car).

I'm probably totally off and you end up drastically increasing your drag, but it might be worth consideration.

[Piwoslaw]

How about "pop-up windmills", that spring up from your car when you apply the brakes? This turns your momentum into aerodynamic drag and then into electricity, instead of into heat. You would still have traditional brakes for lower speeds.
The cost and weigh of such a setup probably isn't worth it.

[MetroMPG]

Regardless of where you place the turbine, the end result will be a net energy loss. There's no free lunch.

The exception would be a turbine which is somehow shielded from the airflow (and where the shield does not negatively affect aerodynamics) but which can pop up into the airflow for the purpose of decelerating. Think: aerodynamic regenerative braking.

Not very efficient, of course (compared to electro mechanical or hydraulic regen).

[MetroMPG]

Haha. You win, Adam.

[theunchosen]

thats pretty much how I thought. Although if you were driving a semi without any aero performance it would be advantageous(if you are going to completely block wind might as well produce juice) buts its easier and more efficient just to reduce drag.

[jamesqf]

Originally Posted by MetroMPG

Regardless of where you place the turbine, the end result will be a net energy loss. There's no free lunch.

Well, not strictly true - look up "landsailing". All you have to do is to somehow manage to plan your driving so that you always have a strong crosswind, and you're home free :-)

In some of my Rube Goldberg moments, I've toyed with the idea of a telescoping vertical airfoil that extends when wind conditions are right...

[MetroMPG]

jamesqf: true for a fixed foil, but I'm not sure how that would help the turbine question...

Coincidentally, I just learned yesterday that the front wheel pants on the U of Waterloo's solar car have adjustable leading edge slats, specifically to try to take advantage of crosswinds. You can sort of see them in this pic:

[Cd]

At first I read this post and thought we were talking about home generators.
With the recent hurricane near my area, this would have been a great thing to have, since most of the roads were flooded and gas was very hard to come by.
A vertical windmill generator would be great to have in a hurricane ( if you could anchor it well )
Now ... on to automotive aplications - Popular Mechanics ( or was it Popular Science ?) had a little write up on a company that was attempting to produce the very thing you are talking about.
I don't have the magazine anymore, but I remember it had the bold title " Detroits' new 80 MPG cars " ( What a joke -here we are almost a decade later ... ) The magazine was circa 1999-2000.
Anways back to the idea. The vehicle that was modified was an electric van with what looked like a large shop fan turned sideways mounted on the roof. As the van moved forward, the wind spun the blades and charged the batteries. To overcome the drag penalty, the blades turned flush as the revolved.
Like almost everything Popular Science/Mechanics touts as the next greatest thing, this idea went nowhere.
Good luck finding the article and the company that was going to produce this thing.