Gavin Shoebridge – an electric vehicle nut, a keen environmentalist

                Electric Car Conversion Blog By Gavin Shoebridge

October 5th, 2009 at 8:42 am

Using Wind Turbines on Your Electric Vehicle

Using Wind Turbines on Your Electric Vehicle

electric car with fans

I’ve been asked many times over the years “why I don’t install a wind turbine on the front of my electric car to make it drive further.”

I’ve also had well-meaning advice on how I should install a generator attached to one of my car’s wheels, so that while driving along I can top up my batteries without plugging in.
To the novice it sounds perfectly logical, and a great way to boost your car’s range. But once you start to understand the energy losses involved, it starts losing it’s appeal. Put simply, because of inefficiencies, putting a wind turbine on your car’s roof will not boost your range. On the contrary; due to the wind resistance & extra weight of the fan, it’ll actually reduce your car’s total range.
If you’re like me, you’re probably not totally convinced yet, so to translate it into English I’ll run through some very basic calculations:

Let’s say your car needs 10 kW of power to drive along a nice, flat road at the legal road speed. In EV terms, that economy’s not too bad.

Now let’s say you put a wind turbine on the roof. This wind turbine puts out 0.5 kilowatts of power, which is wired straight to your battery pack. It sounds good so far, but this is where we have to factor in the inefficiencies (or losses) of the wind turbine.

Even if this wind turbine was a good one, at best it would be somewhere around 50% efficient. That means to put out that 0.5 kilowatts of power I mentioned, it’s actually using a full 1 kilowatt just to turn the generator behind the fan blades. That takes us back to zero (no gain at all).
Next on the list of losses is wind resistance (also known as drag) which pushes against the entire fan – and it’s more than you might think. Possibly another kilowatt of wind resistance. Remember when you were a kid and you had a little pinwheel fan on a stick? When you ran around, the pinwheel spun, but do you remember the pressure it put onto your hand? The stick pushes into your hand because there’s a good chunk of wind resistance in that little pinwheel. The same goes for a big turbine!

This all means that the wind turbine on the roof of our car is now causing the car’s motor to work harder to keep the car at the same speed, using (for argument’s sake) an extra kilowatt of power. There’s other losses to keep in mind too, such as weight, heat and noise losses and they all add into the total amount of energy used.
To sum it all up, let’s put it into a rough equation:

  • Car Driving without fan: +10 kW
  • Fan Generation: +0.5 kW
  • Generator Resistance: -0.5 kW
  • Wind Resistance: -1 kW
  • Other Losses: -0.5 kW

So after installing the fan, you’ve come out worse off with an extra 1.5 kilowatts of power required to move your car along the same road, at the same speed with the fan on the roof. Altogether, the fan uses more power than it can create.

There is a positive side to this story though. The wind turbine can still serve a purpose on an electric vehicle, but only if the electric vehicle was not using energy at the time. For example, if the electric vehicle was parked, or if it was just rolling downhill you could use a turbine to top up the battery pack. In that case there is available energy being wasted which could be reclaimed.
That’s the effect of wind turbines on electric vehicles in a nut shell. As for bedeni motors & perpetual motion machines, they’re a whole other story.

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10
  • John C. Briggs
    12:52 pm on December 14th, 2009 1

    Well said Gav. Can the cars be powered by sheep though?

  • mohan kumar m.g.
    10:05 am on May 29th, 2010 2

    I am indeed surprised to read the comments given.Why do you think of too many turbines (rather fans) as shown in the photographs. Give me a chance to design a turbine in a car. I am confident that I can run a car with my design which I have in my memory. What I need is a designer engineer who can give the final shape. Before that I want patent procedures. Though my idea may look very simple it is going to rule tomorrow world.

  • girish
    12:20 pm on July 20th, 2010 3

    very good car

  • mr
    9:29 pm on June 7th, 2011 4

    we have to put this idea and test it to be sure 100% do you know if anyone actually build one and test it?

  • John K
    5:54 am on August 4th, 2011 5

    I am a bit dissapointed. You started the article talking about the turbines on the “front” of your car, where of course there is drag anyway, and then transitioned to the rest of the article placing them on the roof, additional drag, without explaining the inefficiencies involved placing them on the front..

  • Shahul Hameed K.P
    12:40 am on December 12th, 2011 6

    Hello guys… I have come up with a much radical wind turbine design for vehicles… Currently am working on field experiments…

  • someone
    1:18 am on May 16th, 2012 7

    i understand that the fan blades from a wind generator would cause resistance but what if you made them adjustable to where the blades can lessen the angle in order to lessen the resistance in that it would keep them spinning enough at higher speeds and instead of just trying to run 1 set of battery’s i think it would be a better idea to run 2 sets one to be powering the engine and 1 to be charging and take over when the other set has used up its charge not only would you increase the range of the car of doing this but in theory its range might only be limited to the life of the battery so explain how 2 sets with the right adjustments would not work

  • vinay
    5:56 am on January 19th, 2013 8

    im indeed surprised by the number of fans installed. i dont think so many fans are required and instead of a car the idea would probably work on a two wheeler.

  • Tommy
    11:42 pm on April 5th, 2013 9

    I agree with Mohan, there is a way to implement a wind turbine in a vehicle and benefit from it. I too want a patent but I will elaborate a little. I once came across a wind turbine that was circular in shape. It had minimal drag because it had a minimal height distance and it had steel panels that would close ofter turning. There is also another way have a horizontal wind turbine on your roof and have it exposed through the roof no more than maybe a few inches. These are of coarse just ideas but I believe a lot better than fans. Just my ideology no offense to the poster.

  • Sean Davis
    8:45 pm on October 4th, 2013 10

    The information above was accurate at the time, However due to current technology and materials available now, It is more than possible, It can be a reality to have a wind turbine / vehicle hybrid today. I just hope the Automotive companies do not jump on the band wagon just yet.

 

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