would something like this actually work? Not sure if this is posted elsewhere.. very interesting..
Strap This Wind Turbine To Your Electric Car and You Can Drive Forever
Strap This Wind Turbine To Your Electric Car and You Can Drive Forever
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Car Mounted Wind Turbine to Charge car while Driving
- Thread starter RainmakerJL
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deonb
Active Member
lolachampcar
Well-Known Member
Reminds me of the first day I got my MS. I drove over to Advance Auto to pick up some cleaning supplies and started getting lots of questions about the car. The employee behind the counter started telling me that he thinks all they have to do is put an alternator on the electric car so that the alternator will charge the battery when the car is moving and you can run the car basically forever. I tried explaining the physics behind why that wouldn't work, but wasn't getting anywhere. He still thinks his idea will work....
mitch672
Active Member
Oh sure, perpetual motion machines are commonplace... If there was no gravity, friction, you know, that "physics stuff" 
swaltner
Active Member
The chuckles are because if this actually worked (created more power than the added drag on the vehicle), it would be what is known as a perpetual motion machine, which is against the laws of physics. Since energy can neither be created nor destroyed, the energy the turbine is creating is coming from somewhere, namely the electric motor moving the car. Due to energy losses (friction - air resistance, bearings in the system) and not the conversion from air moving by the blades to electric power, the turbine can NEVER be more than 100% efficient let alone, even 100% efficient. Let's say the turbine is generating 5kW of electric power at highway speed. Awesome, but to get that 5 kW power, your electric motor had to put an extra 10 kW of power into the system to maintain your speed. That's not good if you're trying to improve range.
Perpetual motion - Wikipedia, the free encyclopedia has a much better summary of perpetual motion than what I'd like to type up right now.
The only way these would have any value is if they were deployed when the vehicle was parked and would then rotate into the prevailing wind. That way, you would be adding energy to the system. HOWEVER, your net energy increase probably would be negative. You would either have them deployed when the vehicle was driving (greatly increasing the drag at all times) or would have a much heavier mounting infrastructure to retract them "in flight", but here again you're also reducing the efficiency of the vehicle by hauling around the extra weight at all times for what would amount to a very small amount of electricity being put into the battery.
Perpetual motion - Wikipedia, the free encyclopedia has a much better summary of perpetual motion than what I'd like to type up right now.
The only way these would have any value is if they were deployed when the vehicle was parked and would then rotate into the prevailing wind. That way, you would be adding energy to the system. HOWEVER, your net energy increase probably would be negative. You would either have them deployed when the vehicle was driving (greatly increasing the drag at all times) or would have a much heavier mounting infrastructure to retract them "in flight", but here again you're also reducing the efficiency of the vehicle by hauling around the extra weight at all times for what would amount to a very small amount of electricity being put into the battery.
lolachampcar
Well-Known Member
There are more complex forms of course....
One of my high school friends came to me wanting to use my machine shop (and me, of course) to build his hydrogen generator. Its the old story of the concentric tube electrolysis device to separate water into hydrogen and oxygen. He got these plans to build one that goes in a car using the battery to start the process then the alternator to keep it going. He swore up and down that you could drive off water alone.
I did some quick math proving that flow in the annulus between the concentric tubes would have to be supersonic to support a car running down the road at 30 mph. That did not slow him down in the least. I was a nay sayer and he was just going to go get it built somewhere else. The guys on the internet told him there would be non-believers like me. I suggested going somewhere else was a very good idea, perhaps the best he'd ever had
One of my high school friends came to me wanting to use my machine shop (and me, of course) to build his hydrogen generator. Its the old story of the concentric tube electrolysis device to separate water into hydrogen and oxygen. He got these plans to build one that goes in a car using the battery to start the process then the alternator to keep it going. He swore up and down that you could drive off water alone.
I did some quick math proving that flow in the annulus between the concentric tubes would have to be supersonic to support a car running down the road at 30 mph. That did not slow him down in the least. I was a nay sayer and he was just going to go get it built somewhere else. The guys on the internet told him there would be non-believers like me. I suggested going somewhere else was a very good idea, perhaps the best he'd ever had
On a side note (and I'm not an enormous MythBusters fan) has anyone seen the MythBusters "Blow Your Own Sail" episode? Same concept. But it turned out that if you had a fan that put out enough air it would reflect back off the sail and provide thrust, thus moving the boat. Of course, they glossed over the fact that if you simply reversed the fan you'd have far more thrust and would go faster.
FWIW I ordered one for $99.99 and will be installing it in my Leaf.
Who needs a Model S when this can take me for free non-stop anywhere.
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Who needs a Model S when this can take me for free non-stop anywhere.
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Ok, I know what I am posting is completely different, but it is so cool, and so similar in appearance not to post.
This car uses a windmill to travel faster than the wind. But it is dead downwind, and not at all a perpetual motion machine, more like a weird mechanical sail car.
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You can extract wind energy with a stationary device A.K.A. windmill.
You can extract wind energy in a moving vehicle if there is a differential velocity between surface velocity and wind speed A.K.A. sailboat or the vehicle above.
You cannot extract wind energy if the wind is generated by a moving vehicle, but the differential velocity is zero.
But I understand that many people have a hard time differentiating these three.
You can extract wind energy in a moving vehicle if there is a differential velocity between surface velocity and wind speed A.K.A. sailboat or the vehicle above.
You cannot extract wind energy if the wind is generated by a moving vehicle, but the differential velocity is zero.
But I understand that many people have a hard time differentiating these three.
nwdiver
Well-Known Member
gavine
Petrol Head turned EV Enthusiast
The best analogy I could think of that would make these alternator believers understand is to ask them if they could plug a spotlight into a solar panel and shine it on the panel to power the light. The panel only turns a small portion of the light into electricity so there's no net gain.
