# Add a wind turbine to a car?

by The_Thinker
Tags: turbine, wind
 P: 1 I was thinking about this last night. Surely a wind turbine on top of a car as it travels at speed would generate free energy. Even if it only powers 20% of the car, this would be a great success for our planet. I think it is definately possible. One of us just needs to design it and show the formulas to prove it would be more fuel efficient. 'The energy is in the wind'
PF Gold
P: 784
 Quote by dec2012omg I think it is definately possible. One of us just needs to design it and show the formulas to prove it would be more fuel efficient. 'The energy is in the wind'
The point is that the formulas have been determined a long time ago. They are basic and clear. You can't get something for nothing. If you get power from the wind, it ultimately came from the power that you put in via gasoline.
 P: 2,055 It would yield a net loss in energy. Remember this golden rule: When searching for efficiency, anything that affects the thing you want will yield a net loss. We are using an engine to push the car forward, the point is that using this motion to power a wind turbine will take speed fromthe motion, meaning the engine has to work harder to push the car forward. engine > motion > wind turbine As you can see adding a wind tubine to a car is basically just powered by the egine enyway. However if you had a wind tubine that operated only when the engine was not causing motion (going down a large hill say) THEN you would get a gain. TO get "free" energy (you dont get something for nothing), you need to get it from things that would otherside be thrown away.w Which is why adding a tubine to the exhaust would work.
Mentor
P: 22,313
 Quote by dec2012omg I was thinking about this last night. Surely a wind turbine on top of a car as it travels at speed would generate free energy. Even if it only powers 20% of the car, this would be a great success for our planet. I think it is definately possible. One of us just needs to design it and show the formulas to prove it would be more fuel efficient. 'The energy is in the wind'
Welcome to PF. I'm not sure how to explain it any clearer than it already has. The wind moves a wind turbine by appying a force to it in the direction the wind is moving. In other words, for a wind turbine on top of the a car moving forward, the wind pushes it backwards -- slowing the car.
 P: 2 OK so the turbine causes drag, but you have the momentum of the car so maybe you would get a slight overall net gain of energy i.e. enough to power a mobile phone...?
P: 2
 Quote by DaveC426913 Still no. In order for the turbines to generate power, they must produce drag.
yeah but you have the momentum of th vehicle so doesnt this more than counteract the drag?
 P: 2,055 Read the above. If you take energy from something useful. You LOSE! Ie it would be more energy efficient to simply use the electricity generated by the engine. engine > altenator > phone engine > motion > wind tubine > phone. It adds more steps the energy has to take when ultimately it comes form the same source.
P: 15,319
 Quote by xxChrisxx Read the above. If you take energy from something useful. You LOSE! Ie it would be more energy efficient to simply use the electricity generated by the engine. engine > altenator > phone engine > motion > wind tubine > phone. It adds more steps the energy has to take when ultimately it comes form the same source.
Yup. pr0nChrispr0n is right. It's all coming from the gasoline anyway. Why put more steps in between? You've already got a source of electricity.
P: 2,055
 Quote by DaveC426913 pr0nChrispr0n
Mentor
P: 22,313
 Quote by pronjay OK so the turbine causes drag, but you have the momentum of the car so maybe you would get a slight overall net gain of energy i.e. enough to power a mobile phone...?
Momentum isn't energy.
 yeah but you have the momentum of th vehicle so doesnt this more than counteract the drag?
Momentum isn't force either.

Please understand: we aren't saying that the turbine doesn't generate energy, we are just saying that the turbine steals that energy from the car's engine.
 Sci Advisor PF Gold P: 1,478 i agree...you can not get something for nothing ...what you can do to improve things is to capture and utilize the high temperatures produced by the IC..both antifreeze in the cooling system and waste exhaust.. this is going to waste and..the drag produced by radiator opening could be reduced/eliminated to up the MPG. there it is...available energy in the form of heat..going to the atmosphere...convert this and you got the ticket!!
 P: 336 hmmm..."turbine on the exhaust"..... what about perm magnets on the intake turbocharger rotor "antifreeze in the cooling system and waste exhaust" big peltier device to change heat transfer to electricity (from my understanding with an engineer here that worked with peltier devices they will produce electricity from temp transfer, although not as effieient as power in to transfer heat) given as much as most cars sit vs drive, the wind turbine would work good with a "docking station" for the hybred car just not a good idea on the car at speed dr
P: 15,319
 Quote by dr dodge hmmm..."turbine on the exhaust".....
Would cause back-pressure on the exhaust system.
 Quote by dr dodge what about perm magnets on the intake turbocharger rotor
You're expending energy getting the thing up to speed, then you're going to steal that energy for somewhere else???

You're not thinking critically. You're just pointing at components and asking if it's possible to tap energy from them.

 Quote by dr dodge given as much as most cars sit vs drive, the wind turbine would work good with a "docking station" for the hybred car dr
OK, stick one on your roof then. If there's access to the grid (which is why there's a docking station there) then there's no point to attaching a wind turbine at the docking station. Attach it somewhere in the grid that's more efficient for function and just have wired into the grid.

The whole point of what we're talking about is devices on the car when you don't have access to recharging or refueling.
Mentor
P: 22,313
 Quote by dr dodge hmmm..."turbine on the exhaust".....
Like a turbocharger...? Or you could use the turbine directly to power a generator.
 what about perm magnets on the intake turbocharger rotor
Yes, but it is already an energy recovery device, so you probably don't gain any more by doing this.
 "antifreeze in the cooling system and waste exhaust"
If you mean waste heat recovery then yes.
 big peltier device to change heat transfer to electricity (from my understanding with an engineer here that worked with peltier devices they will produce electricity from temp transfer, although not as effieient as power in to transfer heat)
Correct.
 given as much as most cars sit vs drive, the wind turbine would work good with a "docking station" for the hybred car just not a good idea on the car at speed dr
Correct.
Mentor
P: 22,313
 Quote by DaveC426913 Would cause back-pressure on the exhaust system.
Yes, but the gain is greater than the loss. Turbochargers do, in fact, improve efficiency for a given power output.
 You're expending energy getting the thing up to speed, then you're going to steal that energy for somewhere else??? You're not thinking critically. You're just pointing at components and asking if it's possible to tap energy from them.
A turbocharger is already an energy recovery device - he's just thinking of other ways to use it.
P: 2,055
 Quote by DaveC426913 Would cause back-pressure on the exhaust system.
You can tune around the loss, exhausts acutally need 'back pressure' to work correctly and allow tuning. A turbine generating electricity is only the same as a turbocharger, in terms of how it affects the exhaust.

On the whole a turbocharger is better than a turbine, because increasing the spcific output of the engine is more useful that lots of electricity generation. From a cost vs outcome perspetive. Making the engine produce the same power at a lower specific fuel consumption is more effective than adding batteries and trying to do a hybrid system.

This is the reason for the current trend in engine downsizing, improved efficiency with no appreaciable power and performance loss. Made especially juicy by variable turbo geometry reducing/eliminating lag problems.

I guess you could add a low pass turbine at the end of the exhaust system, just to try to steal that last bit for electiricty generation.
P: 3
 Quote by The_Thinker If supposing we were to add a wind turbine connected to a generator to a moving car, would we be able to get the air flowing around the car to turn the turbine and therefore gain some energy? If it is possible, is it economical? if it is, is it practical? would there be a loss? would there be any gain in overall efficiency?? A friend of mine wants to do this project for collage and wants to implement this idea... I just want to know if it is practical or not... So... what do you guys think?
i don't think it ia possible because there are factors to be considered
1. the place to place the turbine
2.the efficiency of converting the energy from the wind turbine for the car's use
 P: 82 i think it is possible. a paddlewheel behind the car in its wake can extract the energy. it will decrease the drag coefficient of the car aswell.

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