I wasn't aware that the alternator was not sufficient for the task of charging the car's battery. . .

And, oh yeah, this is about the tenth time this has been suggested here. Other participants far more intelligent than myself have already explained why this won't gain anything.

The drag of the impellers would exceed their power production at speed. Parking-lot deployable wind turbines are a better idea.

http://www.whynot.net/ideas/720

http://www.whynot.net/ideas/4100

this video seems to exemplifies this faulty idea.

http://video.google.com/videoplay?docid=7946363986129135783&q=wind+generating+car&total=70&start=0&num=10&so=0&type=search&plindex=0

WE ARE NOT TALKING ABOUT ALTERNATORS HERE - THE BASIC IDEA HERE IS DESIGNA IMPELLER WHICH HAS THE MINIMUM DRAG - THE BIG QUESTION IS CAN WEDESIGN A LOW DRAG IMPELLER - IT SHOULD BE POSSIBLE - WHAT WILL THE EFFICIENCYOF SUCH A IMPELLER? - HARD TO PREDICT - WE JUST CANNOT JUST JUMP INTOCONCLUSIONS WITHOUT TRYING IT OUT.

How do you plan keeping the thing from exploding at higher speeds?

I think it's a hoot that the video shows an aerodynamic car with decidedly unaerodynamic fans attached to it. The noise from the fans must be unreal.

Yeah, baby! This is a "cool" car. That's what I want to tool around in!

EVERY IDEA LOOKS IMPOSSIBLE AND IMPROBABLE TILL THE FIRST WORKING MODEL COMESOUT. IT WAS THE SAME CASE WITH THE WRIGHT BROTHERS

Every idea may look impossible, but engineering and mathematics give us the level-playing field to test the ideas even before they are made.

It should be easy to do math to quantify how much impeller-area can generate so-many watts and such-and-such a speed--once you've selected your impellers and generator or alternator. Then you do the math to find out how many watts a car with a frontal area (including the impellers) and Cd would require to go that fast.

But in-fact we know that it would be impossible for it to generate more than it uses from the laws of thermodynamics and recognition that some energy is lost to inefficiencies-drag and friction.

But we don't actually need to do the calculations, because the guy with the video Has built the car. I think if it worked, he'd be on the news by now.

For the same reason I don't use a flashlight to power a solar cell to charge my flashlight batteries: it won't work.

But nothing is preventing you from buying a solar cell and some rechargeable batteries to power the flashlight to power the solar cell; if you can get that to work, you may wish to graduate to building a car-mounted impeller to charge car batteries. I know it won't work, but I'll be the first to defend your right to try to make it work.

Don't bother asking me for development funds, I'm working on my own "cold fusion" reactor, and after I get that to work I'm going to tackle "zero-point" energy...

A series of small "micro" fans mounted perhaps behind a grill on the front of a car might minimize the aerodynamic drag. The energy produced could be enough to at least make a hybrid more efficient, or extend the range of a plug in electric. It has been demonstrated in small wind turbines for rural areas that a series of small fans turning a single shaft cam operate more efficiently with less wind that a single large one.