wind generator?
 

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.

Hi,

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

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.

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.

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).

Haha. You win, Adam.

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.

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...

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:

http://www.automation.com/images/new...0_x_188%29.jpg

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.

Whitcomb winglets, seen sticking up on the tips of some airliner wings, recover energy from the wingtip vortex. Theoretically, one can recover some energy from a turbulent wake, but it is easier to prevent it. Those winglets would do just as much good as extra wing area, but are used to save space on the ground.

Way off topic ... kind of out in left field.
I know I am not the first person to see a pickup truck with a fan ( house fan ) in the bed of the truck.
What is funny is to see the fan turning at full speed.

I think it would be more affective to add streamers to your mirrors, they would add less drag and be easier to install and give less disappointment.

You know, the Bugatti Veyron has an air brake: when the brakes are applied, the spoiler tilts forward. Last week's Top Gear illustrated this (if you're not in the UK, there are plenty of ways to watch it online).

Still, however, I tend to agree that there would be some cost/weight/complexity/aero penalty no matter what.

Someone who's handy with hydraulic systems could probably make something that piggybacks onto a car's brake line circuit, however.

Failing that, one could conceal a turbine-powered generator inside the car, with Naca ducts as inlets and outlets, with simple flaps that open and close via vacuum or brake lines. There would be minimal aero penalty, and it would be slightly simpler to engineer.

ok, how about the ribbon wind generators, throw a couple of them in place of the grill slats, or at least in a high pressure area that will see not a ton of flow. all these take is a little wind to move, and the differentiating pressure instead of windspeed of the grill would get them vibrating nicely I think, with no aero drag induced, possibly even help with that. or throw them along the bottom, specifically after the dirty air of the tires or such, no real drag penalty, but plenty of turbulance to vibrate those nicely.

now combine that with the shock absorber/generators, and you could extend your range really far. they dont really have to provide all that much power, any would help since it would always be there is the car or wind is moving, which, well, at least around here, always is.