Windmill powered turbines

[Cristatus]

I was on a 6 hour road trip today and was just wondering the following items on the way:


Put a windmill power generator on top of a highway/motorway/freeway, whatever you call it

The natural airflow of a vehicle (especially trucks) goes upwards

Using the above point, the airflow would create some wind for the generators

These generators can be as low as the tunnels caused by bridges of roads going above a highway/motorway/freeway. It is better illustrated using this picture.

If you have been to Europe, you will see that most of those overpasses (I just remembered what they are called) are maybe less than a meter above the trucks.

If the blades' lowest point is just the same amount, then this could be placed on on top of every light pole


I know it is expensive, but would it be possible?

EDIT: forgot to upload the images. Damn bullets don't work properly. Gonna fix it

 

[MobiusPizza]

Whether much energy can be generated is questionable. Turbines would merely turn at all. The power souce is also unreliable. there aren't many trucks are there?

 

[Cristatus]

Originally posted by: AnnihilatorX
Whether much energy can be generated is questionable. Turbines would merely turn at all. The power souce is also unreliable. there aren't many trucks are there?

Well, the slowest lane (the right most lane in left hand drive countries) is usually full of trucks.

 

[MobiusPizza]

Displaced wind around the vehicle would roughly be around 5m/s (A moderate gust of wind) and decrease exponentially as you get away from the vehicle. So if the turbines are safely placed at some distance, say 1m away from the vehicle; It would barely be turn by the wind.
Wind wouldn't be very strong since air is a fluid (gas) and being stationary before the vehicle blaze through it. If you mount the turbines on the vehicles it would have been better; but of course totally impractical.

Wind turbines needs 10m/s of wind speed to be economical; that's why they are only build high in windy areas.
You might get away by placing a lot of small turbines through out the motor way; But the cost would be astronomical to implement regardless of any benefits it brings. I still doubt the idea that they would even turn at all. If you try turning a dynamo connected to a lamp you'd know. It's different to turning a dynamo without "load" on it.

 

[TankGuys]

It's a good thought, but the aforementioned reasons help explain why it probobly wouldn't work.

There is also another angle to consider. If you put those tubines up to extract useful energy out of the "wind" caused by passing cars, one of two things is going to happen with that air flow:

1.) The air flows up because the passing cars push it. If that air then turns a turbine, it necessarily encounters a resistance. This means the cars have to push it harder for it to still move, so in essence, you're simply making the cards burn more fuel in order to push the air to turn the turbines. Adding all those extra steps would be vastly less efficient than just buring the extra fuel in a standard power plant.

2.) The resistance provided by the fans means the air just finds a different direction to move (path of least resistance) so they don't turn at all.