Can a Wind Turbine Improve the Efficiency of a Moving Car?

[sasi_skv]

i read in an article that, if we channel the wind to the generator, it will increase drag force to the car. so, the car's speed will decrease.
I also doing research about wind energy.
Are you doing this research?

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?

 

[DaveC426913]

If you slice a pickup truck into the equation it might work.

I think a bank of small turbines, placed behind and below the rear window of a pickup truck would both generate power and reduce the aerodynamic drag of the vehicle.

Still no.

In order for the turbines to generate power, they must produce drag.

 

[OmCheeto]

Still no.

In order for the turbines to generate power, they must produce drag.

True. But the design of trucks is so dreadfully bad in the first place, I can't imagine something streamlining the back end, not making the vehicle more efficient, even a bunch of mini-turbines.

But as I think I implied in my previous post, simply making the vehicle more aerodynamic is much more economical. And I should probably add now, that it is the only logical solution.

The article associated with the image of the truck I posted, stated that the gas mileage went from 25 to 32 mpg @ 70 mph, a 28% improvement. I agree with you that a slew of mini-me turbines, strategically placed, would probably not come close to generating such an improvement.

 

[russ_watters]

True. But the design of trucks is so dreadfully bad in the first place, I can't imagine something streamlining the back end, not making the vehicle more efficient, even a bunch of mini-turbines.

Adding wind turbines the the back end of a truck does not make it more streamlined, it makes it less streamlined (as was already said). Adding a turbine to anything makes it have more drag than it had before you added the turbine.

 

[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 definitely 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'

 

[Borg]

I think it is definitely 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.

 

[xxChrisxx]

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 don't 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.

 

[russ_watters]

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 definitely 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.

 

[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...?

 

[pronjay]

Still no.

In order for the turbines to generate power, they must produce drag.

yeah but you have the momentum of th vehicle so doesn't this more than counteract the drag?

 

[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.

 

[DaveC426913]

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.

 

[xxChrisxx]

pr0nChrispr0n

 

[russ_watters]

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 doesn't 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.

 

[Ranger Mike]

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!

 

[dr dodge]

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 into 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

 

[DaveC426913]

hmmm..."turbine on the exhaust"...

Would cause back-pressure on the exhaust system.

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.

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.

 

[russ_watters]

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 into 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.

 

[russ_watters]

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.

 

[xxChrisxx]

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.

 

[AYANTAYO]

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

 

[lazypast]

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.

 

[Cyrus]

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.

<smacks forehead>...you just had 5 pages of explaining why you can't do this. Did you read any previous posts?

 

[Cyrus]

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

Ditto for you. I really don't understand why anyone is posting what they *think* when you all have been given sufficient fact as to why this will not work. One should avoid "I think" or "I believe" when making engineering statements. Either it is or it isnt. This thread has probably reached the point of diminishing returns.

 

[chayced]

To think I just read 5 pages of this...

To put it in complete layman's terms. Hold your hand out the window of a moving car. Then hold your hand out the window while holding a fan. The drag caused by the fan pushes your hand back harder now. If you have a 100% efficient wind turbine and a 100% efficient car engine you get all the drag added back as energy, but why? It would be easier to just directly couple the car engine to a generator, and that assumes everything is 100% efficient which is impossible. There is no way you can win.

If you decide to reduce drag and place a turbine in it's place then it's the same result. 10Kw required to keep the car at highway speeds, you reduce the drag to save 3kw then add a turbine that generates 1kw at 30% efficiency. Yup you win it now takes 10 kw to drive the car minus the 1kw you now generate, so 9kw. But, if you can reduce power required by 3kw then why add the generator? You can now drive at highway speeds on 7kw vice 10.

Somebody lock this thread please.

 

[Cyrus]

To think I just read 5 pages of this...

To put it in complete layman's terms. Hold your hand out the window of a moving car. Then hold your hand out the window while holding a fan. The drag caused by the fan pushes your hand back harder now. If you have a 100% efficient wind turbine and a 100% efficient car engine you get all the drag added back as energy, but why? It would be easier to just directly couple the car engine to a generator, and that assumes everything is 100% efficient which is impossible. There is no way you can win.

If you decide to reduce drag and place a turbine in it's place then it's the same result. 10Kw required to keep the car at highway speeds, you reduce the drag to save 3kw then add a turbine that generates 1kw at 30% efficiency. Yup you win it now takes 10 kw to drive the car minus the 1kw you now generate, so 9kw. But, if you can reduce power required by 3kw then why add the generator? You can now drive at highway speeds on 7kw vice 10.

Somebody lock this thread please.

I have no idea where or what these "made up" power values come from.

 

[xxChrisxx]

It was clearly a hypothetical example.

 

[Cyrus]

It was clearly a hypothetical example.

The example doesn't even make any sense, and neither do the numbers. A wind turbine at the back of the car will promote flow separation. You cannot reduce the drag and then add a wind turbine. This is a fallacious line of argument.

 

[chayced]

I have no idea where or what these "made up" power values come from.

Just hypothetical. It really doesn't matter because any numbers you put in will give you the same result. I was just illustrating a point.

Also I don't see where my point gets confusing. Anything you do to generate electricity adds drag. If you reduce drag to add drag then you lose from the inefficiencies of your generator. Why not just reduce the drag in the first place if you already have this ability.

 

[xxChrisxx]

The example doesn't even make any sense, and neither do the numbers. A wind turbine at the back of the car will promote flow separation. You cannot reduce the drag and then add a wind turbine. This is a fallacious line of argument.

It doesn't matter.

It illustrated the point that it adds another layer on efficiency to factor in (the numbers used not being mega accurate is irrelevent). It also demonstrated the extra steps the energy takes from engine to motion.

In the case above even though you think you are winning as you are recovering 1kw from the original 10. You still lose as you could only be using 7.It's a case of spending a pound to save a penny.

 

[Cyrus]

Precisely.

 

[Ranger Mike]

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?

Of course it is possible to add a wind turbine. and this would produce energy in the form of electricity. Not practical or economic...It would take MORE gasoline to do this. anytime you add drag you need at add gas to overcome the drag. you can not get something for nothing. the fact you are adding drag is proven by wind tunnel drag tests. period..case closed.
now what you can do is to recover waste HEAT produced by the internal COMBUSTION engine. combustion being the key here.

 

[FredGarvin]

Perhaps if we build a large, wooden Badger...

 

[russ_watters]

This thread has run its course.

[Hey Fred, congrats, you've invented a new counterpart to Goodwin's law...we'll call it the Monty Python law. It states: "As an online engineering discussion grows longer, the probability of a reference to Monty Python approaches 1."]