Hello,

I'm a CAD Designer at GM working at the GM Technical Center. I asked to work on the Volt and they gave it to me. I'm so excited to be working on this vehicle. Its the coolest car I've ever done. Anyways, I have a question. Does anyone have any information on Vehicular Wind Turbines? I've been told that it doesn't work. I'd like to know if the idea has been tested?

In this house we obey the laws of physics (http://en.wikipedia.org/wiki/Conservation_of_energy)

Seriousely a turbine on a car. to what? power the batteries as its moving on battery power.

Jenkies, you'd never have to stop. Perpetual motion here at last. Why didnt anybody think of this earlier. Who needs battiers at all. Just push start the thing and let all that endless wind power work for you.

Yeah, what the poster above said. People just love this concept but I'm afraid the only way it will work for you is the following setup (the car is stopped and you pull out the turbine from the trunk and set it up). The guy in the video is a few years ahead of everyone in terms of thinking. I won't even mention that the video is quite old! Enjoy.

http://www.youtube.com/watch?v=raLgNo0jhys

I know, I know. Everybody makes fun of me when I bring it up but I think its one of these things that "everybody" knows won't work but has never been tested. I was talking to one guy who made this wind buggy thing and he said that when the impellars are up to speed there is no resistance. And I also just saw a Mitsubishi i MiEV concept car with Vehicular Wind Turbines right up front mounted in the fascia. I don't know... It seems to me that you could use some of the energy(wind resistance) that you have already overcome to spin a couple of small generators and send a small charge back to the batteries. I wonder if its ever been tested.

Cool video though...

fourflush,

Designer. But we do plenty of Engineering in our group. We end up engineering alot of these parts ourselve because the engineers are so busy. Those guys are overworked.

fourflush,

Designer. But we do plenty of Engineering in our group. We end up engineering alot of these parts ourselve because the engineers are so busy. Those guys are overworked.

Volt Designer,

I have always wondered the same thing. Besides the whole we obey the laws of physics here argument against, I think the practical problems boil down to if you can access the power of the wind without messing with the aerodynamics to the point where you are using more energy to overcome the drag than you have originally. There is probably an equilibrium point where you can generate a certain amount of energy from excess wind on the vehicle, but it doesn't increase the drag too much, and thus you can extend the range of the vehicle. There is air coming into the vehicle through the front grill. There is air flowing under the bottom of the vehicle. So if I was designing the vehicle I would ask, is there anywhere already where there is air flowing through or over the vehicle where we can capture energy without causing a disruption in the aerodynamics. I would think that at the front grill would be a good location. Take a look at http://www.humdingerwind.com/. If you incorporated some of these low cost wind generators into the grill, then you could capture energy from the air flowing into the engine compartment and use it to charge the batteries a little more. The air is already going to be flowing there, so there is no breaking any laws of physics, there is minimal increase in drag, and the cost of the technology is low, making for a trifecta of reason.

BigRedFed,

Exactly...There has to be a point where the electricity generated overcomes the drag. I know areodynamics are real finicky. I've worked on programs where they changed the studio surface ever so slightly and got an extra 1 MPG from it. But I think you can make a small generator with some low friction bearings and mount it behind the front fascia. Have a snorkel tube feed it some air throuh a hole in the fascia and have it charge the battery for those long trips.

I just want GM to be ahead of the curve instead of playing catch-up on this one. They have the resoures to study something like this.

I checked out that site....Yeah those rotating wind turbines wouldn't cause much drag at all....thats pretty cool.

I checked out that site....Yeah those rotating wind turbines wouldn't cause much drag at all....thats pretty cool.

Yea, I've been waiting for the Developer kits to come out. I want to get one and see how much enery it creates. I think it would be cool to install them along the edges of my roofline to catch the wind that flows over the house. Then couple that with some solar panels on the roof and maybe go Grid Free down the line.

Designer,

Ok, maybe i was a little harsh in my first post. Its been a long week.

Let me try and explain where i'm coming from. Imagine a calm day, no wind. Your in your Volt driving down the highway at 70 mph. Realative to you there is a 70mph headwind which you have "created" by moving your vehicle through a stationary air mass. So what energy was used to create this wind? for the volt it would be electrical power from the battery pack or gen-set.

So now you want to use a turbine to extract work from the wind you created. At 100% efficiency in the turbine. you could get exactly as much power from the turbine as it took to create the bit of wind to turn it. Since nothing operates at 100% efficiency the turbine will cost you energy depending on how efficient it is. IF its 90% efficient you lost 0.1 kw for every 1 kw generated. Meaning it takes 1 kw of power to push the car through the wind enough to generate 0.9 kw of energy. that 1kw of power would not have to be spent if the the turbine was not on the car.

I understand what your trying to do and its great to think outside the box. but careful that your mind is so open that your brains fall out. There is no free energy. The only way the turbine could be a net positive is if, instead of a calm day, you where driving into a strong headwind. And I would imagine for a normal person that would be a very unlikely scenerio and would not compensate for the additional weight and cost.

Think about it this way. If i put a fan on one end of a tube (blowing into the tube) and a generate on the other. would it run forever? For wind turbines on cars not only would it have to run forever (generate enough power to offset what it takes to create the power. but it would have to convert more than 100% of the energy in the wind so that there is some extra to power the batteries.

Wind turbine on house, good idea. Wind turbine on something you are using energy to move. bad idea.

Sorry guys, I know you love the idea but you can't get something for nothing. Impossible. You just have to trust the engineers, physicists, and scientists on this one. You didn't like the wind turbine setup on the video? I thought that would satisfy you.

Ponder this: Put a 2 foot wind turbine on a very light carbon fiber skate board with a super efficient electric motor on it. There is no wind and the road is flat. The turbine output is directly connected to the electric motor. You spin the turbine by hand to get things started. The generated electricity starts to move the turbine foward and thus the turbine will spin more from the movement though the air. The spinning turbine will provide more electricity to propel the cart forward. If your theories are correct the vehicle will continue to move forward for as long as the road is. Correct? What do you think will happen? Please post your answer and I will give you the correct answer after that. Good Luck!

I agree with Texas on this one. Aircraft, such as the 757 have a RAM air turbine (RAT) that is deploy in the event of loss of power (say running out of fuel at 30K ft, which happened in the late 80s). The RAT turns a generator to send emergency power to the cockpit, so the pilot can get vital info like altitude, airspeed, etc. (Turns out pilots get real upset when their cockpit goes black at 30K ft) The RAT is deployed into to the slip stream and creates a lot of drag, that drag is what turns the turbine and the electric load connected to the generator. Under normal operating conditions power is generated using a PTO shaft from the main engines, or with an APU. Why, because they consume less fuel than using a RAT to generate the power, which would increase drag and cause more fuel to be consumed to maintain cruise airspeed.

If you want to increase the electrical efficiency of the Volt, add a conformal solar panel the roof. When the sun is shining, it will add X amount of current to the system with no increase in drag. This will have the net effect of increasing the electrical efficiency of the system by X%, thus extending range. Of course, that X% increase in efficiency will come with added cost.

I agree with you Rooster.

The only excess energy that can be recaptured is from the intertia created once the vehicle is in motion. This is already being done with regenerative breaking.

Even if some energy can be harnessed with wind it would likely not be enough to offset the costs. As Rooster point out, solar cells produce energy without any sacrifice to drag and continue to work when the vehicle is at a stop...but again the costs outway the benefit. With the advances in photovoltaics (www.nanosolar.com), we may see them on the rooftops of the Volt eventually.

Lastly, photovoltaic cells actually work surprisingly well in cloudy conditions because they use the entire light spectrum. It is thermal solar generation that suffers almost complete shut down during cloudy days because of its total reliance on infrared light only from the sun.

Sorry guys, I know you love the idea but you can't get something for nothing. Impossible. You just have to trust the engineers, physicists, and scientists on this one. You didn't like the wind turbine setup on the video? I thought that would satisfy you.

Ponder this: Put a 2 foot wind turbine on a very light carbon fiber skate board with a super efficient electric motor on it. There is no wind and the road is flat. The turbine output is directly connected to the electric motor. You spin the turbine by hand to get things started. The generated electricity starts to move the turbine foward and thus the turbine will spin more from the movement though the air. The spinning turbine will provide more electricity to propel the cart forward. If your theories are correct the vehicle will continue to move forward for as long as the road is. Correct? What do you think will happen? Please post your answer and I will give you the correct answer after that. Good Luck!

What I think will happen, is that eventually the skateboard will stop. Why? Simple, the amount of energy put into the system is never more than the original amount. However, my question to you is, will the skateboard go further with the turbine than without. The answer to that is, it depends. If the initial energy generated is enough to overcome the weight of the turbine, then the skateboard will probably go further with the turbine running than with the same aerodynamic profile/weight and no turbine running. Take your skateboard, place it going downhill and a slight incline then with the correct size motor and aerodynamic profile, you will not only go all the way down the hill, but generate enough energy to go up the next hill. No one here thinks that they can get anything for free and for the man who loves to expose solar panels on the roof, despite all the inefficiencies, I expect more of an open mind from you.

If you have a small generator, that has a low cost of development, such as that I linked to in my previous post at humdinger, can you recapture enough energy from the wind, say moving through the grill into the engine compartment or going out the exhaust pipe, to overcome the small cost of installing it in the car to the point where the cost is recouped from a few extra miles able to be reached by the electricity generated/recaptured?

That is the question, not can we add something to the car generate perpetual motion. If you don't have an answer to the question, even if it is no, then give the answer and if you know why not, then it would be nice of you to say so. I'm sorry, but just trusting the "engineers, physicists and scientists" is just not within me, especially since the answer "they" just gave, doesn't even begin to address the actual question.

Sorry, You just cannot generate more energy through the grill than it would take to overcome the drag from the turbine. I'm sorry you don't understand the difference between this and a solar panel. I'm trying to come up with an explanation that is good enough for you to believe. Very difficult. Perhaps you think you can make the turbine so slippery that it will have no resistance. Even if that was the case you have the resistance in the generator. Understand? You don't just spin a generator freely and energy comes out. It will have a resistance greater than the energy it produces (the amount greater is it's efficiency) If it was 100% efficient (does not exist) then it would produce the same amount of energy that it took to spin the shaft.

Now I know you are going to hold on to this argument and change it so you don't feel bad and I understand. Unfortunately, many people make this mistake and also there are many people in this world that take advantage of people who don't understand physics. The water powered car comes to mind. Anyway, since you are so passionate about the idea I think the best way to spend your time is to get a good education on how things work. Go to the MIT site and you can actually get free lessons on all related subjects. It

"If you have a small generator, that has a low cost of development, such as that I linked to in my previous post at humdinger, can you recapture enough energy from the wind, say moving through the grill into the engine compartment or going out the exhaust pipe, to overcome the small cost of installing it in the car to the point where the cost is recouped from a few extra miles able to be reached by the electricity generated/recaptured?"

The answer is no.

The quest for perpetual motion will never die, but what few realize is that we already have it.

Anytime you see a perpetual motion machine, it is always, well, a machine. Are machines free? I think not. Can anyone think of a machine, or device, that we already have, which will produce energy without a fuel cost?

I thought you might.

Texas, FourFlush,

I've had a few engineers at GM explain it the same way. Basically if you have energy over here, and energy over there, and you put a system in between them, you are going to lose energy in through system. But like BigRedFed said, I'm not thinking about perpetual motion, just an auxillary generator. If I read your posts right you say that the drag that the tubine would cause would overide any energy created by the turbine. The 757 RAT analogy was pretty convincing. I don't know. I don't want to give up on it just yet but I find your reasoning hard to aurgue with. And I can relate back to my experiences in the wind tunnel on the last program I was working on. They changes the surface ever so slightly and got an extra 1 MPG out of the car. Anyways. Thanks for the dicussion that was helpul.

This has got to be the most civil group of people on any discussion site I've ever visited. PERIOD.:)

Hey Tagamet,

I read the article (ABC was it?) where you were interviewed. The article left me with a positive impression, although I had to chuckle at the "cult like following

[QUOTE=Rooster;827]Hey Tagamet,
I read the article (ABC was it?) where you were interviewed. The article left me with a positive impression, although I had to chuckle at the "cult like following

[QUOTE=Texas;806]Sorry, You just cannot generate more energy through the grill than it would take to overcome the drag from the turbine. I'm sorry you don't understand the difference between this and a solar panel. I'm trying to come up with an explanation that is good enough for you to believe. Very difficult. Perhaps you think you can make the turbine so slippery that it will have no resistance. Even if that was the case you have the resistance in the generator. Understand? You don't just spin a generator freely and energy comes out. It will have a resistance greater than the energy it produces (the amount greater is it's efficiency) If it was 100% efficient (does not exist) then it would produce the same amount of energy that it took to spin the shaft.

Now I know you are going to hold on to this argument and change it so you don't feel bad and I understand. Unfortunately, many people make this mistake and also there are many people in this world that take advantage of people who don't understand physics. The water powered car comes to mind. Anyway, since you are so passionate about the idea I think the best way to spend your time is to get a good education on how things work. Go to the MIT site and you can actually get free lessons on all related subjects. It

Hmmm..so you say you are working on the Volt design:D

I'll be direct. I'm going to ask some questions. Please don't divulge anything that isn't for public knowledge.

What everyone is saying about perpetual motion is correct. Energy cannot be created, nor can it be transformed without losses. BUT, you could conceivably recover energy with wind turbines. Basically, when the car is traveling it is transferring energy from the vehicle to the amonst losing it in other ways. Most of the energy imparted to the air is from direct collision with the car from vertical components of frontal surfaces, skin friction along the sides, and from separation of flow. There is no way on the vehical to recover the energy lost on from the separation of flow nor skin friction drag. Theoretically you could use turbines in lieu of some vertical serface or at the grill. The problem is that you will recover significantly less energy than if the car is properly disigned aerodynamically and for only the necessary inflow for cooling. Any savings by improved aerodynamics are 100% savings of energy, because the energy need not be expended in the first place so it is drawn from the battery. Any energy extracted by the turbine, must have first come from the battery and only the enrgy left after ALL of the losses is recaptured.

So, it energy can be recaptured, just not practically.

Now, for the questions:

Is the underside of the car relatively smooth and seemless?
Has the height and/or width at the rear been reduced from the prototype?
Is the frontal inflow area the same or reduced from the prototype?
Are the sideview mirrors the same as the prototype?
Is the final outerbody design very similar to the prototype?

I understand if you can't answer any of the questions.

I understand the physics just fine.

Sorry my persistent forum fellow. You do not quite understand the physics yet. However, I think you are getting closer! I don't care how you intend to extract energy off of a system it will always take more going in than you will get out. Always! No discussion. I know, that boring efficiency loss talk again. I'm sorry, it's just a fact of nature. When the wind blows over this strip it vibrates and this vibration causes a magnetic core to move though a coil. Much like a speaker in your stereo. Yes! if you move the speaker cone in your speaker you can generate an electrical current. Very cool by the way. However, do you feel your body move that cone? The amount of work into it minus the efficiency losses of the system will equal the energy you get out. Bummer eh? Anyway, don't give up the fight for understanding. I suggest you read up and don't forget to run some experiments. You don't have to buy one of those fancy things from that guy, you can make a good representation in your garage. Good luck and let me know how it goes.

Oh, I always try to imagine things extremely exaggerated to understand a new concept. For example, if you made a large enough wind strip you could use it for a parachute because the drag caused by the vibrating strip would slow you down enough for a nice gentle landing. Physics is cool, don't you think?

Dear GM CAD Designer,
I’m glad someone at the Tech Center is thinking outside the box. Although conventional physics is correct and you can’t create energy without using energy, your are right in thinking there is more to this than a simple yes or no. You should begin searching for and testing different turbine designs in a wind tunnel for vibration, Coefficient of DRAG, gyroscopic effects and energy output. Not all wind turbines work the same way. Although there are many naysayers out there including your co-workers, I have a list of U.S. Patents issued for “Wind Energy capturing device for moving vehicles”. I have also looked into several pinwheel, propeller, and helix turbine designs. If you are interested in the information I have gathered, I would be glad to share it with you outside this forum. You may e-mail me at Nhern202@go.com
By the way, I attended the Volt Nation meeting at the NY Javits Center 3/19/08 and spoke to Alex in depth about the battery usage and charging methods. I didn’t get into the use of wind energy on the Volt with her because one person, who asked about solar on the roof like on the Cadillac Provoq, was told that would be a second-generation design consideration.

Nelson

Hello,
Does anyone have any information on Vehicular Wind Turbines? I've been told that it doesn't work. I'd like to know if the idea has been tested?

being that I drive an electric vehicle everyday (one that I converted myself) I get asked this exact same question, or varients of it nearly every day. I get asked about putting generators on the rear wheels, wind turbines, solar panels. Here are some reasons why people often think this is possible:

People don't realize the sheer volume of electricity required to move the car. My car draws about 20,000 watts just to cruise down the road at 40 mph. By comparison, a typical alternator in a regular automobile only generates about 420 watts of power when the thing is at its best. As you can see, that is about 2.1% of the power needed to move my vehicle. Incidently, it would put about a 3% or 4% drag on the car, which means in the end I would loose power.

The same is true for a wind turbine. In this case, it would probably generate about 1% of the power needed to move my car, but it would generate about 5% drag at 40 or 50 mph, in essence it would hurt the overall battery life. Solar panels, if implimented correctly, might not cause any drag. However, they would only generate about 0.05% of the power neccessary to move the car. True, over time they could recharge the batteries if left sitting in the sun, but it would take about 2 or 3 weeks to get a full charge. I actually have a friend who has solar panels on his electric Fiero, and what I just said is about accurate for his vehicle as well.

So overall, I think the misconception people have is they look at automotive alternators and wind turbines and they think, "well, those don't seem to difficult to move, it shouldn't put much drag on the vehicle." And they are right. The problem is they don't realize how much power is needed to actually move the car. They are an order of magnitude off. So, in essence, putting a generator on the car capable of generating 20,000 watts of power would put SUBSTANTIAL drag on the vehicle, way more than it would generate.

Adric22

"My car draws about 20,000 watts just to cruise down the road at 40 mph."

That's a good reference point. What kind of car is it?

That's a good reference point. What kind of car is it?

It is a 1993 Eagle Talon. Here is a website about my conversion:

http://galaxy22.dyndns.org

The amount of work into it minus the efficiency losses of the system will equal the energy you get out.

Well, duh. I'm not asking, in any of this, for more than is being put into the system initially. I am only wondering if there is a practical way of recapturing energy. The discussion would have been shorter and less condescending on both sides if you would have read that instead of going on a tirade concerning how you can't break the laws of physics. Koz was the only one to notice that both I and Volt Designer were going for energy recapture instead of perpetual motion and had the wherewithal to answer that question, so I respect his answer, even though it is not one I necessarily like. I would like to see some experiments done and how much drag is increased by installing something in the grill and maybe one day when I have the time, money and a garage, I will. Until such a time as that, I am done beating this dead horse.

At speed there is an air pressure pocket at the cowling of most cars, could be used as an inlet with less drag than a snorkel. Just a thought.

(Pokes dead horse with sharp stick) Yup, this horse ain't movin.

So whats the difference between a wind turbine thingy and say something like something like a turbo charger or super charger on an ICE. Obvisouly you cannot make more power than you put in it but you can make it more efficient. In the case of a turbo charger you are generating more HP by using the exhaust.

Well, duh. I'm not asking, in any of this, for more than is being put into the system initially. I am only wondering if there is a practical way of recapturing energy. The discussion would have been shorter and less condescending on both sides if you would have read that instead of going on a tirade concerning how you can't break the laws of physics. Koz was the only one to notice that both I and Volt Designer were going for energy recapture instead of perpetual motion and had the wherewithal to answer that question, so I respect his answer, even though it is not one I necessarily like. I would like to see some experiments done and how much drag is increased by installing something in the grill and maybe one day when I have the time, money and a garage, I will. Until such a time as that, I am done beating this dead horse.

So you think you got it? I'm not so sure. However, maybe you could tell me what energy you plan on recapuring? The energy coming over the grill in your car? If that's your answer then you still don't understand.

There was another poster talking about what was the difference when talking about a turbo charger. There is a big difference. Firstly, the turbo charger is using wasted heat energy that is in your exhaust and is using that to turn a compressor to inject more oxygen into your combustion chambers for a more complete combustion. We are not talking about capturing non-expanding gasses and turning an electric turbine. That would just be an obstrution and cause more losses than you get. If you are recapuring the heat loss from an ICE than that is a possiblity because of the huge losses an ICE sufferes. There are several new technologies targeting just those loses (using thermoelectric materials).

Actually the horse does not seem to be dead yet. It's still twitching. ;)

...Actually the horse does not seem to be dead yet. It's still twitching. ;)

Where's my gun when I need it.....

Well.. I suppose the idea here, is that if you can find some type of energy loss on the car that you are going to definately always lose, then find a way to recapture that - then you are on to something. Of course, we can already do that in most hybrids with regenerative braking. In this case, the friction of the brake-shoes is an obvious form of energy loss, but is also neccessary. So that was used for energy recapture.

So if you wanted to start searching around the vehicle for every energy loss and figure out ways to convert it to power - go for it. Just make sure that conversion doesn't cause more drag on the vehicle. I can give you an example just from the top of my head. There is a lot of waste heat on various components. You could use the peltier effect or even build little stirling engines running little generators to convert that heat back into electricity. It can be done, but I bet the cost of it would outweigh the benefit.

At speed there is an air pressure pocket at the cowling of most cars, could be used as an inlet with less drag than a snorkel. Just a thought.

You know…I hate to say it, but on second thought that just might work.

If you put an inlet at a location of max dynamic pressure (Vair = 0), say the front bumper, and ran a duct to a turbine generator keeping the duct cross sectional area constant, and then vented the duct to a location where there is a slight vacuum (air pressure < ambient air pressure), I can see that netting a slight reduction in power (Amps) to maintain a constant highway speed. There would be no increase in dynamic pressure over the vehicle frontal area (A vehicle), and there would be a slight decrease in dynamic pressure over the area of the duct (A duct) -- instead of the air being slowed to 0 MPH at the location of the inlet, it would flow into the duct. In fact, were the duct vented to a vacuum location, the air would be sucked into the duct, and that could potentially yield a minute amount of thrust. So at constant speed, would the power generated by the turbine + any power saved as a result of lower dynamic pressure (or minute thrust) at the inlet (A duct), be > than the increase in power required to overcome any duct & turbine skin friction drag ? It might, but you’re not talking a huge increase in efficiency.

An analogy would be winglets on aircraft, they add wing surface area and increase in the skin friction drag, but they reduce induced drag. The net is a slight decrease in overall drag. In this case, I see the potential for a slight decrease in the overall power required (a slight increase in efficiency) to maintain a constant speed. That said, dynamic pressure is a function of the square of the air velocity, so at 600 MPH you have a lot of dynamic pressure causing a lot drag, and any small reduction in net drag pays big dividends in the power required to maintain constant airspeed. At 70 MPH, not so much.

It would take a high fidelity CFD program or wind tunnel test to verify. The bigger question is would any potential gain in efficiency be worth the added cost and complexity? I would be very surprised if it did. I still think a conformal solar panel would pay larger efficiency dividends.

When I was in school, one of my class projects was to scuff a wood sphere to various roughnesses and find the coefficient of drag in a wind tunnel. True to expectations the rougher ball had a lower coefficient of drag because it caused the are to transition from laminar to turbulent at lower speed (lower Reynolds numbers really). On of the things I wanted to try (while still an idealistic youth) was adding some thing to the front of a car to trip the boundary layer early. When you transition from laminar to turbulent, the coefficient of drag drops by almost an order of magnitude. You could in theory do the same thing with some small wind generator on the leading edge of the vehicle. again like Rooster said, you want a wind tunnel and some good CFD code, and frankly it probably would not be worth it, but in theory, why not.

Are some of you suggesting starting with a very poor aerodynamic design and then adding a wind turbine to it to trip the boundary layer and also use the wind turbine to get back some of the lost energy from the very poor aerodynamic design? Maybe starting with an optimized aerodynamic design that would not benefit from adding a wind turbine to it would be a better idea. Just a thought.

Ok, I think I figured out a test model for you. You start with a very square shape, like a truck. Then, bore a 2 foot hole through it which would then allow all the air to flow freely though it. Then add a wind turbine to it to partially block flow and get some electrical power from it that is a bit less than the previously freed air (efficiency loss of the turbine). If you do it just right you might be able to use less energy than the original square box. Ooops, with the wind turbine you loose the ability to carry cargo. Back to the drawing board.

Horse - still twitching

Since electricity from wind is so popular, I thought I

I typed this once but I was timed out or something so I'll try it again.
Something like the Humdinger BigRed posted could work I think.
1. We know the designers are facing thermal managment issues. Plus there is and ICE powering a generator. These let us know that there will be a grill for cooling air comprable to what we're used to in the design of cars.
2. That opening will be made large enough for adequate airflow at slow speeds in stop and go traffic. This means there will be excess drag and airflow at higway speeds.
3. There will be a grill for styling cues anyway. If the grill was replaced by a humdinger or the like you would not be adding any increase in drag over a plastic grill. The humdinger would have to "tuned" for higway speeds. I assume it would only be effective at certain speeds if it's working off resonance and natural frequencies, etc.

The utimate consideration. Is it's cost low enough to offset just burning an extra ounce or two of fuel for the same trip, multiplied over the life of the vehicle?

Edit - I think a big hold up to this would be that the grill needs to be sturdy enough to protect what behind it as well as not care if it's raining or if salt is flying up in it.

I typed this once but I was timed out or something so I'll try it again.
Something like the Humdinger BigRed posted could work I think.
1. We know the designers are facing thermal managment issues. Plus there is and ICE powering a generator. These let us know that there will be a grill for cooling air comprable to what we're used to in the design of cars.
2. That opening will be made large enough for adequate airflow at slow speeds in stop and go traffic. This means there will be excess drag and airflow at higway speeds.
3. There will be a grill for styling cues anyway. If the grill was replaced by a humdinger or the like you would not be adding any increase in drag over a plastic grill. The humdinger would have to "tuned" for higway speeds. I assume it would only be effective at certain speeds if it's working off resonance and natural frequencies, etc.

The utimate consideration. Is it's cost low enough to offset just burning an extra ounce or two of fuel for the same trip, multiplied over the life of the vehicle?

Edit - I think a big hold up to this would be that the grill needs to be sturdy enough to protect what behind it as well as not care if it's raining or if salt is flying up in it.

imflyn, So you think you can vibrate that strip without putting any work into it? It doesn't matter what fancy form a wind generator comes in. I wish people got that. It will have to offer resistance in order to move it's parts and the electrical generator. You can't just use the free air that is flowing over it. Whatever airflow is going over whatever surface will only be restricted more by any device that is converting energy from one form to another. I hope other people on-the-fence about this can grasp this concept. The flowing air is not freely flowing. it is only flowing because you are pushing the car through the wind. The more resistance the car sees the more energy needed. If you put a wind generator of ANY form in the the path of the vehicle and attempt to extract energy away from the air flow generated by the moving car (not a side wind - which could be harnessed) it will cause the car to expend more energy than you can possibly recover. If it didn't you would have created a machine that creates net energy. None have been created yet. Also, don't you think there are all kinds of brilliant scientists and engineers out there that would have tried this already? Not one working prototype? Doesn't that make you the least bit suspicious?

Kos,

Yes I'm actually designing the front fascia/grill. And yes, I'm looking at the latest studio surface as we speak. Unfortunatly, thats about all I can tell you if I want to keep my job. I wish I could go into specifics because its sooo cool....but I can't. Sorry.

You know one of the reasons I brought this up is the Cadillac CTS-V. Our group did that car and we ended up designing a brake cooling duct that ran from a hole in the front fascia and snaked around so that it blew directly on the brake caliper. And I thought if they are willing to accept that much drag to cool the brakes why not a wind turbine. But I'm past the denial stage and moved on to acceptance. Its hard to fight the laws of physics. I've enjoyed the discussion though.....

Are some of you suggesting starting with a very poor aerodynamic design and then adding a wind turbine to it to trip the boundary layer and also use the wind turbine to get back some of the lost energy from the very poor aerodynamic design? Maybe starting with an optimized aerodynamic design that would not benefit from adding a wind turbine to it would be a better idea. Just a thought.

Ok, I think I figured out a test model for you. You start with a very square shape, like a truck. Then, bore a 2 foot hole through it which would then allow all the air to flow freely though it. Then add a wind turbine to it to partially block flow and get some electrical power from it that is a bit less than the previously freed air (efficiency loss of the turbine). If you do it just right you might be able to use less energy than the original square box. Ooops, with the wind turbine you loose the ability to carry cargo. Back to the drawing board.

Horse - still twitching

I'm not suggesting that you start with a poor aerodynamic design and make it "better" by tripping a boundary layer. I'm suggesting that you start with a great aerodynamic static design and augment it with a dynamically deployed "thingy" the could trip the boundary layer such that the coefficient of drag drops for a given speed. I was not clear about that in my last post. The "thingy" could be a wind driven generator of some sort. In reality I doubt you could generate sufficient electricity to make it worth it, but as far as I know it is theoretically possible.

What the others are suggesting is that, since you are already displacing a certain amount of air, you might as well try to capture some of that energy otherwise lost to that displacement. I don't think anyone thinks this is as simple as strapping a couple of propellers on the side of the Volt and out pops enough power to drive the car. I don't think anyone has proposed such. There have a been a few suggestions made as to how one might go about utilizing wind turbines such that the net energy loss goes down, and I think all of us who have suggested these concepts understands that without analysis and test, all of those ideas are at best half-baked, and are likely not worth the effort.

Kos,

Yes I'm actually designing the front fascia/grill. And yes, I'm looking at the latest studio surface as we speak. Unfortunatly, thats about all I can tell you if I want to keep my job. I wish I could go into specifics because its sooo cool....but I can't. Sorry.

You know one of the reasons I brought this up is the Cadillac CTS-V. Our group did that car and we ended up designing a brake cooling duct that ran from a hole in the front fascia and snaked around so that it blew directly on the brake caliper. And I thought if they are willing to accept that much drag to cool the brakes why not a wind turbine. But I'm past the denial stage and moved on to acceptance. Its hard to fight the laws of physics. I've enjoyed the discussion though..... I think you guys did the CTS-V with great style and quality, give clout and bragging rights to the engineers!... glad to hear you are on this project as well. Keep up the good work and put GM back on top!!

Can you PUUULLLLEEEESSSSE tell us that it won't look like a Cobalt? Pretty Please? (insert whimpering sobs here)

Great concept...however Texas is the winner.

Think of it this way, the air that you want to funnel away from the top of the hood has to eventually end up somewhere. Where are you planning on allowing this air to exit? If it's through the radiator and into the engine compartment, I can verify that the air will eventually face substantial resistance, causing a large reduction in velocity.

Most people don't realize how much air pressure can build when air must change directions. For those who remember, think back to the 1969 Z-28 Camaro. The entire engine was sealed off from the engine compartment and the air was fed from where? The air pressure at the base of the windshield was so great and pushing so hard against that area, that GM designed the "Cowl Induction" hood to feed that engine at RPM! When you talk about an opening allowing air to come in contact with a radiator at a much more aggresive angle than that Camaro windshield, you will find that the build-up of air pressure will allow MUCH less air to actually travel over your regenerative system than you may anticipate.

Turbos in an automotive setting are similar. They use air to make more energy (in a fuel/air system), but there is no such thing as a turbo that is 100% efficient. The power made from a turbo also uses the BTU's provided by the extra gasoline to make the power increase worth while for an automotive application.

The concept is VERY thought-provoking...and I'm sure even Texas would agree with me on that statement. However the practical application would be a disappointing failure with current technology.

Having that been said, it's a pleasure to discuss these options. Bouncing ideas off each other may just lead to a big leap for the Volt in the future!

Are some of you suggesting starting with a very poor aerodynamic design and then adding a wind turbine to it to trip the boundary layer and also use the wind turbine to get back some of the lost energy from the very poor aerodynamic design? Maybe starting with an optimized aerodynamic design that would not benefit from adding a wind turbine to it would be a better idea. Just a thought.

Ok, I think I figured out a test model for you. You start with a very square shape, like a truck. Then, bore a 2 foot hole through it which would then allow all the air to flow freely though it. Then add a wind turbine to it to partially block flow and get some electrical power from it that is a bit less than the previously freed air (efficiency loss of the turbine). If you do it just right you might be able to use less energy than the original square box. Ooops, with the wind turbine you loose the ability to carry cargo. Back to the drawing board.

Horse - still twitching

Let me try and explain this better.

Take a look at the most aerodynamic car I’ve seen to date, the Aptera (http://www.aptera.com/details.php) Type 1. The designers use that solar panel on the roof to run a fan to cool the interior, and they also use it to reduce overall vehicle drag. Outside air is draw into the vehicle cabin from somewhere, most likely the cowl area, and the solar powered fan vents it out two ducts on either side of the rear license plate. The rear of Aptera, where the license plate hangs is vertical (perpendicular to the road). When the Aptera is moving, this is an area of vacuum (low pressure), as the airflow separates. Thus, this rear area is a major contributor to the overall small Cd of the vehicle. Aerodynamically speaking, by venting the cabin air into this area of low pressure, they increase the air pressure in this area by a small amount, which decreases the overall Cd of the vehicle compared to if they did not vent the cabin air out these ducts. Aerodynamic drag is the summation of the air pressure around the entire vehicle, thus air pressure is higher in the front of a car than it is in the back. Increase the air pressure at the back, and you reduce drag.

An important point to remember is the body structure of a vehicle is doing work on the air, as it is pushing air out of the way as a vehicle travels down the road. This is basic Force = Mass X Acceleration, and Work = Force X Distance physics. Technically speaking, the structure of the vehicle is under load (either tension or compression) and any structure under load deflects. If designed correctly, the deflection is minute. None the less, the structure is doing work as it is reacting against the aerodynamic load. So think of the question as, is there any cost effective way to recover some percentage the energy that is otherwise being consumed by the vehicle structure pushing the air out of the way?

Aptera’s design does it by using a solar panel to run a fan that vents cabin air out the 2 ports in the back of the vehicle. That reduces the vehicle overall Cd, which reduces the amount of energy being absorbed in the structure for any given speed - a brilliant concept by the way.

In my example, I’m suggesting similar concept, but rather than using a solor powered fan I'm using max dynamic air pressure. Assuming there is a vertical surface on the front of the Volt; say the area on either side of the front license plate, then that will be an area of max dynamic pressure. Any solid surface perpendicular to the airflow slows the air to 0 MPH at its surface, and is an area of max pressure. In other words, 100% of the aerodynamic force possible is being absorbed by the vehicle structure if the on coming air is being slowed to 0 MPH, thus you can not create more aerodynamic drag without putting energy into it. (i.e., think reversing the thrust on airplane to slow it down). So if you put an inlet in this area of maximum dynamic pressure, and duct it to a small turbine; you should be able to recover some percentage of the energy (maybe 10%) that is otherwise being absorbed by the vehicle structure. If you then vented the air exiting the turbine via a duct to an area of low pressure on the rear of the vehicle, just like on the Aptera, you can also lower the Cd of the vehicle, as the air would flow into a region of low pressure at the rear which would increase the air pressure at the rear. The fact that there is an inlet with a duct leading to a turbine can not increase drag beyond the drag that would be present if there was a vertical solid surface – that would violate physics. If there isn’t enough air pressure to spin the turbine and drive a small generator, then the turbine doesn’t spin.

That said, I doubt any energy recovered would by worth the added $ cost, but it’s not violating any laws of physics. You are absolutely correct, you can not create energy. However, with smart design you can recover energy that is otherwise being lost.

Another idea is to forgo the “turbine-generator concept” altogether. Instead, just put inlets on either side of the front license plate and duct the high dynamic pressure air out ports on the rear of the vehicle. That would reduce the overall vehicle Cd, and would be a less expensive solution. Finding creative ways to increase efficiency is the fun part of engineering.

OK, I’m done…shoot the horse so it doesn’t have to suffer any longer. :)

Thank you for what you were able to share. Maybe you'll be able to throw us more of a bone once the design is locked and made public.

Seems though there is a bit of consensus here about recouping energy losses. It could be done in theory but it's not the most practical approach. Rooster better described what I was saying earlier. All of this talk has crystalized an idea that may be worth a look.

One of the E-flex concepts, Provoq I think but maybe another, has adjustable vanes in the front grill. The idea was to close the vanes when airflow was not needed for cooling. There are 2 options along this vein (no pun) that seem plausible at first blush:
1. There will probably always need to be cooling while the Volt is operating, so closing the front grill completely is probably not an option. At highway speeds, the entire grill area may not be needed. Perhaps there could be a simple, elegant design created for panes that close the less efficient portions of the grill at highway speeds (perhaps gravity held open and closed by high wind pressure). I am thinking 3 segments to the grill area and closing the outer 2.

2. I believe this second option has more promise but is also a more radical change. Remove or minimize the front grill and place an air intake on the underside of the car utilizing a vaned air damn. The front grill is a large source of drag. Under the car is still a high pressure zone, higher than above the hood. The pressure at this point is acting upward on the vehical and not apposing the direction of motion. I know there will still be a drag cost, but I believe the overall drag would be noticeably reduced especially if the air could be practically vented at the rear.

Definitely generation 2 thoughts but maybe the engineers will have a little more interest in this.

I guess the US Patent office is in the business of issuing patents for non-functioning ideas.:rolleyes:

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6838782.PN.&OS=PN/6838782&RS=PN/6838782

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6373145.PN.&OS=PN/6373145&RS=PN/6373145

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6138781.PN.&OS=PN/6138781&RS=PN/6138781

Believe me when I say, there are many more. My favorite is the third one because it shows a drawing where air intake starts in the front grill of a car and travels through an airflow tube/channel that exhausts from the rear of the car. Looks almost like what KOZ described.

I guess the US Patent office is in the business of issuing patents for non-functioning ideas.:rolleyes:

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6838782.PN.&OS=PN/6838782&RS=PN/6838782

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6373145.PN.&OS=PN/6373145&RS=PN/6373145

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6138781.PN.&OS=PN/6138781&RS=PN/6138781

Believe me when I say, there are many more. My favorite is the third one because it shows a drawing where air intake starts in the front grill of a car and travels through an airflow tube/channel that exhausts from the rear of the car. Looks almost like what KOZ described.


As a matter of fact they do have a history of granting patents for non-workable devices. The following explains it well enough:

"Patents
Devising such inoperable machines has become common enough that the United States Patent and Trademark Office (USPTO) has made an official policy of refusing to grant patents for perpetual motion machines without a working model. One reason for this concern, according to various skeptics, is that a few "inventors" have used official patents to convince gullible potential investors that their machine is "approved" by the Patent Office.[citation needed] The USPTO Manual of Patent Examining Practice states:
With the exception of cases involving perpetual motion, a model is not ordinarily required by the Office to demonstrate the operability of a device. If operability of a device is questioned, the applicant must establish it to the satisfaction of the examiner, but he or she may choose his or her own way of so doing.[2]
And, further, that:
A rejection [of a patent application] on the ground of lack of utility includes the more specific grounds of inoperativeness, involving perpetual motion. A rejection under 35 U.S.C. 101 for lack of utility should not be based on grounds that the invention is frivolous, fraudulent or against public policy.[3]
The USPTO has granted a few patents for motors that are claimed to run without net energy input. These patents were issued because, skeptics claim, it was not obvious from the patent that a perpetual motion machine was being claimed.[citation needed] Some of these are:
Howard R. Johnson, U.S. Patent 4,151,431

Johnson, Howard R., U.S. Patent 4,151,431 "Permanent magnet motor", April 24, 1979
Baker, Daniel, U.S. Patent 4,074,153 "Magnetic propulsion device", February 14, 1978
Hartman; Emil T., U.S. Patent 4,215,330 "Permanent magnet propulsion system", December 20, 1977 (this device is related to the Simple Magnetic Overunity Toy (SMOT)),
Flynn; Charles J., U.S. Patent 6,246,561 "Methods for controlling the path of magnetic flux from a permanent magnet and devices incorporating the same", July 31, 1998
Patrick, et al., U.S. Patent 6,362,718 "Motionless electromagnetic generator" , March 26, 2002
Green, Willie A., U.S. Patent 6,526,925 "Piston Driven Rotary Engine", March 4, 2003 "Fluid driven device utilizing a leveraged system with minimal displacement"
Goldenblum, Halm, U.S. Patent 6,962,052 "Energy generation mechanism, device and system", November 8, 2005 "A chamber with a partition which lets gas molecules flow one way and not the other. The pressure which builds up on one side of the partition is used to drive a generator."
Flynn, Joe, U.S. Patent 6,246,561 "Methods for controlling the path of magnetic flux from a permanent magnet and devices incorporating the same", June 12, 2001
Gates; Glenn A., U.S. Patent 6,523,646 "Spring driven apparatus", February 23, 2003 "Energy is stored in the springs and power is generated by way of the various forces which cause the springs to wind and unwind."

http://en.wikipedia.org/wiki/Perpetual_motion

People don't realize how many scam artists use patents to open purse strings. Be careful folks!

Pardon the question; did anyone actually claim a turbine spinning in the wind can power the vehicle perpetually? Claiming you might be able to recover a small percentage of the energy lost (<5%) to net a minute improvement in efficiency isn't close to saying you can recover >100% of the energy lost.

Seriously, did I miss something in one of the posts? I thought we were just discussing what might or might not be possible for fun? :confused:

Pardon the question; did anyone actually claim a turbine spinning in the wind can power the vehicle perpetually? Claiming you might be able to recover a small percentage of the energy lost (<10%) isn't close to saying you can recover >100% of the energy lost.

Seriously, did I miss something in one of the posts? I thought we were just discussing what might or might not possible for fun? :confused:


Rooster, I guess the question still remains: what lost energy? Unless you are talking about side winds or tail winds or some other wind energy that is coming from another source (other than the wind generated by the car) then any device that you insert in the car generated wind will cause more drag (and thus will require more energy) than the wind turbine will generate. If your aerodynamic design is so poor that inserting a turbine improves the aerodynamics then you would gain more by just improving the aerodynamics of the system. In the the one patent claim a truck air dam was inserted to help the air get around the box shape. In this dam a turbine was inserted to get back the "wasted energy". I question this logic. The wasted energy to me was the poor aerodynamic design in the first place. Adding surfaces to improve the aerodynamic shape will do more to reduce the energy usage than adding an aerodynamic shape with a turbine. The turbine will only add more drag than adding the aerodynamic shape alone. Does that make sense to anyone? Am I the only one who sees that adding a turbine to get back energy from the wind generated by the vehicle as a crazy perpetual motion concept?

Now if people are talking about dynamically changing surfaces that can change the aerodynamics of the car for different conditions then fine. There are several models out that change their shape already, like a dynamic spoiler. These devices do work but you have to do an analysis to see if the added expense is worth it. It's also a moving part that has to be maintained.

However, adding a turbine to improve the aerodynamics of the overall system instead of adding static or dynamically adjustable surfaces? Sure you could do it. You can do just about anything short of violating the laws of physics. However, I contend that adding a turbine will not only reduce the possible energy savings but you also have the added cost of the turbine, charge controller, wiring, maintenance, etc. I really think people are not thinking clearly about this 'wasted energy'. I think the problem is coming from where people think the energy is coming from in the first place. If the energy is generated from outside the system then you can attempt to harness it. If the energy is generated from within the system then it will be a losing game to try to harness this energy with a wind turbine.

Thus, I think we should move forward in this discussion by first stating what energy you are trying to harness. Outside generated wind energy or inside generated wind. If you say outside then I agree that a system could be designed (as I have stated earlier in this thread) and it would be very intriguing. This system would have to adjust dynamically and be able to close itself when there is no energy to harness. If it didn't have this capability it would be adding drag most of the time. I actually love the idea of a wind generator integrated into the car. Especially when the car is parked. This along with solar panels could get you more than 6 miles-a-day worth of energy (see previous calculations showing how a solar Prius could get 3-6 miles of extended range on a sunny day in Texas).

If you are talking about harnessing the energy that was expended from within the system I'm confident that I could propose a non-turbine solution that would outperform a turbine based solution. My non-turbine solution would have far less complexity and cost.

A poster above said that this topic was thought provoking. Indeed.

Earlier, someone mentioned the idea of a solar roof. I was initially skeptical, solar doesn't have a lot of power density, after we factor in the conversion efficiency (or lack thereof). However, looking at current solar panels and making rough estimates, GM could probably fit about 250W of SPV generating capacity on the roof of a midsize car.

Unless I am mistaken, this is actually not something to sneeze at. Allowing for further losses due to orientation, a car parked in the sun for 8 hours might get a 1KW, perhaps larger, charge in that time. That's about 6% of the battery capacity. Parked for a few days, oriented well, the Volt might get a significant charge.

Aggressive use of SPV on more of the vehicle's surface (roof and trunk lid) might allow as much as 40OW of solar power under some circumstances, even more useful.

Anybody else care to take a stab at this and see if it makes sense. Did I slip a decimal point or two?

There's still the problem of building the panel. Some SPV manufacturers have new processes where thin films can be laid down on aluminum... and probably on a curved surface. But you need protective glass or something over it (heavy) and there might be other issues.

Earlier, someone mentioned the idea of a solar roof. I was initially skeptical, solar doesn't have a lot of power density, after we factor in the conversion efficiency (or lack thereof). However, looking at current solar panels and making rough estimates, GM could probably fit about 250W of SPV generating capacity on the roof of a midsize car.
Unless I am mistaken, this is actually not something to sneeze at. Allowing for further losses due to orientation, a car parked in the sun for 8 hours might get a 1KW, perhaps larger, charge in that time. That's about 6% of the battery capacity. Parked for a few days, oriented well, the Volt might get a significant charge.
Aggressive use of SPV on more of the vehicle's surface (roof and trunk lid) might allow as much as 40OW of solar power under some circumstances, even more useful.
Anybody else care to take a stab at this and see if it makes sense. Did I slip a decimal point or two?
There's still the problem of building the panel. Some SPV manufacturers have new processes where thin films can be laid down on aluminum... and probably on a curved surface. But you need protective glass or something over it (heavy) and there might be other issues.

COST of the SPV's is just plain prohibitve.

Earlier, someone mentioned the idea of a solar roof. I was initially skeptical, solar doesn't have a lot of power density, after we factor in the conversion efficiency (or lack thereof). However, looking at current solar panels and making rough estimates, GM could probably fit about 250W of SPV generating capacity on the roof of a midsize car.

Unless I am mistaken, this is actually not something to sneeze at. Allowing for further losses due to orientation, a car parked in the sun for 8 hours might get a 1KW, perhaps larger, charge in that time. That's about 6% of the battery capacity. Parked for a few days, oriented well, the Volt might get a significant charge.

Aggressive use of SPV on more of the vehicle's surface (roof and trunk lid) might allow as much as 40OW of solar power under some circumstances, even more useful.

Anybody else care to take a stab at this and see if it makes sense. Did I slip a decimal point or two?

There's still the problem of building the panel. Some SPV manufacturers have new processes where thin films can be laid down on aluminum... and probably on a curved surface. But you need protective glass or something over it (heavy) and there might be other issues.

Hi dagwood, If you read around this forum you will see that I'm also a big fan of solar on the surface (SOTS). There's a new company out there called HelioVolt that is working on a print-on technology for building integrated solar applications. There is also a company called XsunX that is working on solar glass. Both are potentially cheap processes. I'm thinking about a car where the entire surface is covered with solar technology. It's not ready now as Tagamet mentioned but I'm sure it will work it's way to the automobile in due time. Throw in a wind turbine that can be set up when the car is parked and you potentially have a system that will give you quite a few miles per day. If you live in the South and don't drive very far you might never have to gas up or plug in again. Now that's freedom. However, don't get your hopes up yet. The technology is a long way away and it will not produce a huge amount of energy. Good enough for extra functionality and a few extra miles. I'm looking forward to having it installed on my next EV. Maybe we should start a SOTS club. ;)

Six pages of wind powering the car????

I think my 8th grade science teacher said it best: "Friction is a bummer"................

:)

Jim I, Our teacher's lecture was titled "Friction is Such a Drag."

Tagamet, Nanosolar claims to be able to produce SPV for $1/peak watt. Certainly, that's not "installed in an automotive application" but it's something that will differentiate the vehicle.

Jim I, Our teacher's lecture was titled "Friction is Such a Drag."

Tagamet, Nanosolar claims to be able to produce SPV for $1/peak watt. Certainly, that's not "installed in an automotive application" but it's something that will differentiate the vehicle.

Just to be clear, I'm 110% in favor of solar and wind power. It's just that both are currently way out of my retired/fixed income price range.

A friend of mine summed this whole thing up in a really good analogy. He said the next time somebody mentioned putting generators or wind turbines on the EV, he was going to tell them to try another approach that is much more efficient - Put large tires and wheels on the back, and small ones on the front. That way, the vehicle is always travelling down hill. It should make it far more energy efficient. Right? AHhahahaha. I laughed so hard.

A friend of mine summed this whole thing up in a really good analogy. He said the next time somebody mentioned putting generators or wind turbines on the EV, he was going to tell them to try another approach that is much more efficient - Put large tires and wheels on the back, and small ones on the front. That way, the vehicle is always travelling down hill. It should make it far more energy efficient. Right? AHhahahaha. I laughed so hard.

Nice one. I wonder if they would stop and consider it. ;)

Jim Roland,

Thanks, we're all fighting like hell to make GM profitable again. This place has undergone an amazing transformation. Its been a wild ride...

Tagamet,

All that I can say is that in my opinion, it still looks cool. If we were at some bar, somewhere, I might fill you in. But over the internet thats all I can say.

All of this arguement against a wind turbine is based on the idea that all of the energy that the car generates is from the engine. And true on flat ground with a flat endless run it would be better to have an efficient engine vs a wind turbine.

But that isn't the entire story on power generated by the car. Think about the energy gained by the car as it rolls down a steep hill. If you have to break, even a little going down the hill, you've scrubbed energy that instead could have been converted to energy by a drag force like a wind turbine.

Not saying it's the solution, but just pointing out that not all energy in the system is created by the engine and that we scrubb excess energy out of the system all the time. That's kind of the idea behind the energy recapture in brake systems for hybrids now. Rather then lose all the energy, you capture some of it back.

All of this arguement against a wind turbine is based on the idea that all of the energy that the car generates is from the engine. And true on flat ground with a flat endless run it would be better to have an efficient engine vs a wind turbine.

But that isn't the entire story on power generated by the car. Think about the energy gained by the car as it rolls down a steep hill. If you have to break, even a little going down the hill, you've scrubbed energy that instead could have been converted to energy by a drag force like a wind turbine.

Not saying it's the solution, but just pointing out that not all energy in the system is created by the engine and that we scrubb excess energy out of the system all the time. That's kind of the idea behind the energy recapture in brake systems for hybrids now. Rather then lose all the energy, you capture some of it back.


Why would you put a turbine on the car when the regen breaking is more efficient and already in place? Also, the turbine would have to automatically hide when not used in your example because the drag it caused would cause you to loose energy. As I stated earlier in this thread you have to differentiate between energy generated from within the system and that coming from outside the system.

This got me thinking of a cool application. Imagine if you will EEstor does in fact come out with a super capacitor that really works. It's very light and can hold plenty of charge for it's weight. If that's the case you might be able to make a very light weight personal helicopter. You start with a full charge go straight up for as long as the battery lasts and then using rotogyro principles you glide back to earth while recharging the super capacitor. When you land you would be able to it all over again, this time not as high. What percentage of the first height would you be able to go? This would make a great science project. ;)

[QUOTE=Texas;1248]Rooster, I guess the question still remains: what lost energy? Unless you are talking about side winds or tail winds or some other wind energy that is coming from another source (other than the wind generated by the car) then any device that you insert in the car generated wind will cause more drag (and thus will require more energy) than the wind turbine will generate. If your aerodynamic design is so poor that inserting a turbine improves the aerodynamics then you would gain more by just improving the aerodynamics of the system. In the the one patent claim a truck air dam was inserted to help the air get around the box shape. In this dam a turbine was inserted to get back the "wasted energy". I question this logic. The wasted energy to me was the poor aerodynamic design in the first place. Adding surfaces to improve the aerodynamic shape will do more to reduce the energy usage than adding an aerodynamic shape with a turbine. The turbine will only add more drag than adding the aerodynamic shape alone. Does that make sense to anyone? Am I the only one who sees that adding a turbine to get back energy from the wind generated by the vehicle as a crazy perpetual motion concept?"

So you want to know where the energy comes from. Fine, I’ll tell you! It is subtracted from the increase in efficiency you would gain from modifying the vehicle aerodynamics in my example. DOH! (Laughing hysterically now) :-)

Dude, it would appear that I’ve been so consumed with explaining how to make this “work”, that I failed to account for the opportunity costs. OK, time for me to eat some serious crow and use the example I’ve been offering to explain this “slight omission”.

Let’s start with a car that produces 250 lbs of drag at 70MPH. If it were electrically driven, the motor would have to generator 250 lbs of electromechanical thrust to maintain a constant 70 MPH.

In my example, I suggest modifying the vehicle aerodynamics by ducting high pressure air from the front of the vehicle to low pressure air at the back. Let’s assume I’m successful and I reduce the vehicle drag by 50 lbs at 70 MPH. So now the vehicle’s motor only needs to produce 200 lbs of electromechanical thrust (250 – 50) at 70 MPH, so my modified vehicle is 20% more efficient. 50/250 x 100% = 20%

I now get the bright idea to install a turbine generator in the duct to capture some of that wind energy that is flowing through the ducts. The installed turbine generates 30 lbs of additional drag, but it also generates electricity. Unfortunately, the turbine –generator combo is not 100% efficient, it’s more like 50% efficient. Thus I only produce enough electricity to provide 15 lbs of electromechanical thrust (30 lbs x 50%). Consequently, the overall drag of my modified vehicle with a wind turbine generator is now 215 lbs. (200 lbs + 30 lbs – 15 lbs)

So I was successful, I added a wind turbine generator and increased the efficiency of the original car. The drag was 250 lbs at 70 MPH, and now it’s only 215 lbs, so I reduced the drag by 35 lbs and increased efficiency by 14%....whohoo victory!

To bad the opportunity cost was a car that was 20% more efficient as a result of the aerodynamic modifications alone. You must do the aerodynamic modification to offset the drag caused by the turbine. The problem is a turbine-generator can never be > 100% efficient. So why would you ever want to use one when you can only recover a percentage of the drag it creates as electromechanical thrust?

Texas, salute for holding your ground, you are correct one this one!

I didn't read each of the patents you posted but the first one is designed to RECOVER some of the lost energy due to drag that is going to be lost in the design of the automobil already.

So that isn't a case of patents being awarded for a device that doesn't do what it is suppose to do.

These concepts work just like regenerative breaking. You loose more energy than you recover but you were going to stop anyway so might at well recover some of your spent energy instead of loosing it all.

It basically comes down to power lost due to drag versus power gained due to generation.

P_lost = P_drag - P_gen

On a normal car, P_gen = 0, so P_lost = P_drag. The only way to make any turbine net positive is when P_gen is non-zero P_drag cannot increase as much as P_gen or P_lost goes up. As Rooster pointed out the power lost due to the generator alone is more than the power gained from that generation. But that doesn't mean the overall power consumed due to drag has to grow by more than the power gained from generation. The addition of a generator could in theory drop the overall coefficient of drag (even while perhaps increasing the frontal area).

However, the net effect has to be so profound that the decrease in P_lost would be worth the cost and maintenance of such a design. I doubt this would ever be achieved.

The addition of a generator could in theory drop the overall coefficient of drag (even while perhaps increasing the frontal area).

Remember for every generator + aerodynamic change you make I can design a aerodynamic only change that will not only reduce the net energy losses but will cost less and need little or no maintenance. Why? Because the turbine will introduce drag and that loss of energy will never be fully recovered by the gain in the turbine's electrical generation. The turbine and generator will always have an efficiency of less than 100%. Even if you could design a 100% efficient turbine and generator your design would still cost more than my pure aerodynamic change and your design would still require a battery charger, wiring, maintenance costs etc. The brass tacks about this problem is that if you are not trying to harness outside energy the turbine system is worse than pointless.

If you are trying to harness outside energy when the car is in motion the turbine system would have to be extremely complicated as it would have to 'hide' itself so as to not introduce net energy losses from forward motion. Without an extremely sophisticated design I can only see a wind turbine being used when the car is stationary. Then the car could charge all day and night and possibly provide a good amount of energy. When the car is moving the turbine would be stowed away.

I just now discovered this thread and I won't let the physicist in me join this now largely-concluded wind turbine debate. But my practical side insists on making these seldom-discussed comments.....

1) The Volt will have an aerodynamically-smooth belly pan, as well as, I believe, every other cost-effective measure today's art allows to reduce drag (perhaps even tiny cameras embedded in its slim mirrors --supplementing the back-up camera we now know it will also have-- allowing the side mirrors to be very small while completely eliminating blind spots)

2) It will also use "deceleration energy recovery" (as well as regenerative braking), which is easily implemented by instantly reversing the drive motor's role, making it a high-efficiency generator whenever the accelerator is released at ANY road speed; this will also keep the car from feeling like it's free-wheeling when decelerating, simulating the EV-equivalent of ICE engine braking

3) It will definitely make use of technology GM has thoroughly developed to open, close or partially open louvers located behind selected grill openings; these inexpensive louvers can be actuator-controlled by road speed and/or underhood temperature to constantly minimize the Volt's drag coefficient under all ambient temperature conditions and at all road speeds

Remember for every generator + aerodynamic change you make I can design a aerodynamic only change that will not only reduce the net energy losses but will cost less and need little or no maintenance.


First, for any aerodynamic static design you come up with, I can come come up with a dynamic design that gets better aerodynamics, and for any non-generating dynamic design, I can come up with a generating design that has the same aerodynamics.

Second, this was never a disagreement about cost or maintenance. I would not want want this feature on my car.


If you are trying to harness outside energy when the car is in motion the turbine system would have to be extremely complicated as it would have to 'hide' itself so as to not introduce net energy losses from forward motion. Without an extremely sophisticated design I can only see a wind turbine being used when the car is stationary. Then the car could charge all day and night and possibly provide a good amount of energy. When the car is moving the turbine would be stowed away.

I do really like the idea of a portable wind turbine that can be deployed when the car is parked. I don't think it should come standard with the Volt, but I would like GM to provide a mounting block right next to the plug-in location. That way I could mount my own wind turbine to the side of the car.

Firstly, I never said just static - in fact earlier I talked about movable real spoilers. Secondly, no. You cannot come up with a generator design that is more efficient than my aerodynamic only design. That was the entire point of this thread. You will have drag losses far in access to the losses I will experience and you will never be able to get that back though the generator because of the efficiency losses. It's a non-sensible exercise in futility, much like this thread. Let it go already. ;)

P.S. Of course it wouldn't be a standard option, I thought that was obvious to most readers.

Firstly, I never said just static - in fact earlier I talked about movable real spoilers. Secondly, no. You cannot come up with a generator design that is more efficient than my aerodynamic only design. That was the entire point of this thread. You will have drag losses far in access to the losses I will experience and you will never be able to get that back though the generator because of the efficiency losses. It's a non-sensible exercise in futility, much like this thread. Let it go already. ;)

I contend that I could come up with a device that has the same aerodynamic effect as your rear spoiler and also has some sort of generation capability.

This has become a "my daddy can beat up your daddy" argument. Since I can never convince you that my idea isn't full of sh*t and you can't convince me that it is, and this could never be settled without infinite time, budget, and a wind tunnel, I agree to let it go.

And I do agree (as you can see from the title of a previous post), it ain't worth it anyway.



P.S. Of course it wouldn't be a standard option, I thought that was obvious to most readers.

It was obvious to me, I was just agreeing with you.

Fair enough. Without access to a wind tunnel, millions of dollars of research and years of experimenting nobody could say 100 percent for sure. Even if 1000 aerodynamic engineers agreed with me AND did the research you would not be convinced because you would feel that they didn't test every configuration.

Looking at the forest for the trees however I feel this was a good debate and maybe got some people thinking about energy. I would also point out that if something like a wind turbine on a car seems so simple yet is so difficult to prove can you only imagine trying to prove global warming? The scientists only have their computer models and are working with a weather system that is so complex that it’s nearly impossible to find cause and effect. The best we can do is employ the best people on earth (and from all over the earth) to work on given problems and then act on their conclusions after a given majority reach agreement. As you can see, we will never have 100 percent certaincy for any complex real-world problem.

I think the debate is not over. This link has a pic of a Mitsubishi shown at the Tokyo auto show. Guess what... it has a generator fan behind the grill! Hmmmm, food for thought!http://www.inhabitat.com/2007/11/06/transportation-tuesday-toyota-i-miev-sport/

Great! When this makes it out to production we will then have an engineering test bed. We can wait for a perfectly calm day and get her up to full speed. We can take turns running the wind turbines and then covering them up with tape. We can then see the difference in power drain. Unfortunately, this feature will probably never make it out of the lab. However, if it does, I'm confident that this design will cause more losses than it gains (unless the intended purpose is for it to gain power when the car is stationary). I look forward to more on this.

Here's a funny video of a wind powered car.
:D

http://www.youtube.com/watch?v=bkcn8ZkvKKc

lol! Priceless. Please don't forget to read the comments. Some people are not quite sure or feel the blades would need to be bigger. It's even more funny because the drivers looks so proud. :) Anyway, I now rest my case.

what a waste of otherwise completely good generators

lol! Priceless. Please don't forget to read the comments. Some people are not quite sure or feel the blades would need to be bigger. It's even more funny because the drivers looks so proud. :) Anyway, I now rest my case.

If that is the closing of your case, then again, you were arguing against a case that no one else was making.

If that is the closing of your case, then again, you were arguing against a case that no one else was making.

Good one BigRedFed, Very nice comment. If you are going try to cut into me you might try to use a proper sentence. I will give it more weight.

Ok, I can explain it to you. Some people were implying that they can put a wind turbine on a car, much like in the video (only smaller and hidden inside the body of the car), and then use that gained energy to charge the battery and thus go further. This would violate the laws of physics. That was the case I was trying to make. Understand now?

Here's a funny video of a wind powered car.
:D

http://www.youtube.com/watch?v=bkcn8ZkvKKc

Holy cow! I've been laughing all night.


Can you just imagine a pedestrian getting hit by that thing! LOL.


Hey Texas... I'm still laughing about the "Benefits of the ICE from an oil man's perspective" That was GREAT.

Ok so now that the horse has been beaten, i just read an idea that actually makes some amount of sense.

This is from the DIY electric car forum and is not my idea but i thought it was novel.

If a turbine was in the car somewhere and had an actuated door (like a scoop or something) that only opened when the brakes were applied. An interesting form of regenerative braking.

I dont think that enough power could be gained from this to warrant the extra weight of the genset but i thought that the idea was far enough out of the box that it shouldnt be immediately discounted.

and it doesnt violate any laws of physics. which is always a good thing.

Recommence the beatings

lol. Of course it would work. Just take that car in the video and pretend that the fans just popped out when you hit the breaks. Now you got me laughing! Like the break pedal had a cable attached to one side and the gas pedal has a cable attached to the other side to hide the turbines. Don't give that idea to those two guys because they might go out and attempt the modifications. :)

Can I just ask one question? Exactly why do you not want to use normal regen? It's more efficient and obviously more practical, don't you think?

Can I just ask one question? Exactly why do you not want to use normal regen? It's more efficient and obviously more practical, don't you think?

why not use both? like the air brake on the veyron

Ha! Yes, I guess if you have enough money you can do anything you want (assuming you don't violate the laws of physics). Might get you a YouTube video!

Im over halfway through this thread, so i appologize if this has been mentioned in the second half.

Everyone has been talking about the wind power generation while the vehile is accelerating or maintaining speed. What about deceleration?

Why not have an enclosed hood which opens when deceleration occurs. Perhaps not just braking conditions, but when load is placed back onto the engine, ie. downhill.

I realize the most electrical gains from deceleration will be from mechanical means, but if you can recoupe some more of the spent engery from the acceleration process, the better, eh?

Hi Storb, Maybe you should read the second part. It gets even better. ;) Before we talk about pop-out wind turbines please ask yourself why you would not want to just use the regen that's already built into the electric car? It will recoup around 70 percent of the energy needed to slow the car down. Is that not good enough? Think of the cost of your device, the maintenance, the space, the efficiency, etc. I'm not saying it wouldn't work (it will!) but do the benefits outweigh the costs? Are there better ways? The car in the video will get positive net power on the way down a hill. Does that make it a practical mode of transportation? Hardly.

let me start by saying I am not an engineer no physisist or even that smart of a guy but common sense gets you eveywhere...

I don't see why using the braking system isn't where we ae going in this conversation?? If the Transmission in the EV switched to a charging system instead of using traditional brakes. meaning when the brake pedal is depressed it increases the load placed on the slowing driveline when spinning the "alternater/charger" which is stepped up due to increased pedal pressure...

I have a 20 year old sears LTV lawn tractor that used a belt pully system where the lever moves the pulley to stretch the belt causing more speed creating a taller gear. Reverse this process to slow down the Car and charge the battery...

as far as the turbine theory what is wrong with using a turbocharger to create boost at highways speeds to help propell the turbine even if the PSI is low turbo pricing is extemely low you can modify a cheap leafblower into a turbo easily...

There will always be drag even if the design engineers went nuts with aeordynamics it still will not make it to production due to crash test safety....

There is theory and reality...
The Volt re-charging ICE is going to be as efficient as possible I am going to assume... the lone Turbine Idea has been beaten to death even though I feel thee may be some Highway driving benefits ... using the downforce created by a rear spoiler would be my first choice due to popularity in design of the the rear spoiler...

sorry for poor spelling I have a 5 month old in my lap while posting this.

NHRAbill,

The Volt's electric motor will reverse as a generator to re-charge the battery when the brake pedal is depressed. This is called "regenerative braking". This feature is included in all most current-generation hybrids, including the Toyota Prius, etc. and is, in fact, what makes them so much more efficient in city driving than non-hybrids.

Thanks for the youtube video, I really laughed.

I think a row of VAWT's (vertical Axis wind turbines) in the rear spoiler that pop up during deceleration would work from a positive energy point of view.

I don't think it would work from a cost point of view though.

I really think four wheel drive with regen hooked to super capacitors is a better way to go. Version two, perhaps, Mr Volt CAD man. With regen being less on the rear than the front 70/30, a smaller motor to be used just for acceleration and regen only, with the main motor for efficiency purposes handling cruising as well as acceleration/regen.

Anyway this thread was worth it just for the video. I really needed a laugh.

Thanks for the youtube video, I really laughed.

Don't thank me! It was another poster a while back. The proud look on the faces of those guys will stay with me for the rest of my life.