A vertical axis wind turbine without the wind! How do they do that? - YouTube
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Wind turbines are everywhere nowadays, and they do a great job of harnessing all that free energy. But as a restless species constantly on the move, we human...
Yet another interesting method for capturing and using wasted energy.
Yeah I wondered about that too. There is a point where the wind resistance will have a significant effect. I just do not know what that point is. Would be interesting to find out.
I wouldn't think it would be real significant in part depending on the drag of rotation, size and location. Which are all variables that can be addressed.
Over all I think this is probably a good thing. It's interesting to see these new technologies being put into place.
I'm enjoying watching the computer age develop.
I remember talking with my late grandmother about her witnessing flight just beginning and I think of her when I see some of the really cool things we have now.
I saw a cool one, it was in Korea I think. In the middle of the highway they made a strip of solar panels. Underneath the raised panels was a walkway and bike path.
They way I look at it, never know until you try. Haha
The energy they are using is the energy of the vehicle after it has already been transformed from the kinetic energy of the moving vehicle to kinetic energy of moving air, to kinetic energy of the physical VAWT and, finally, to the electrical energy by the turbine's alternator...
I used to ride ferries quite a bit, and on every trip across the Sound, there would be several seagulls flying along with the ferry. They got multiple things out of the trip: One would be the food that the people would throw in the air for them, another would be the free ride that they got on the pressure ridge coming off of the bow. They would get in that sweet spot and fly without flapping a bit. The addition fuel that the ferry consumed because of those seagulls is about analogous to the additional fuel that would be used by vehicles cruising along a highway with these turbines installed,eg. so little as to be indistinct and virtually indistinguishable from other sources of resistance.
This entire conversation is wrapped around the presumption that there would be a drop in fuel efficiency of the vehicles travelling along this corridor because of the turbines, which I think is a specious argument to begin with because the effects that it actually has are miniscule, negligible and masked by several much larger factors that affect economy such as a wind speed, directional winds, turbulence, wakes, etc.
The stream of wind created by the vehicles passing at 70 mpg along the smooth median, let's say is traveling at 40 mph, so all vehicles are traveling with a tailwind and a 30 mph head wind, now place the turbines in and the drag of the generator slows the wind down to 30 mph, now the vehicles are dealing with a 40 mph head wind, you don't think that would reduce their mpg?
Let's take the wind out of the equation. Someone comes up with a brilliant idea and says let's put magnets on the underside of all vehicles and induction coils in the road bed and let the wasted energy of the vehicle movement generate electricity, do you think that would cause a problem?
The energy they are using is the energy of the vehicle after it has already been transformed from the kinetic energy of the moving vehicle to kinetic energy of moving air, to kinetic energy of the physical VAWT and, finally, to the electrical energy by the turbine's alternator...
Thomas, I am quite aware of how this works.
Don't think in terms of a single car, think in terms of traffic. The backflow vectors affect the traffic. Vehicle x causes an effect which impacts vehicle y.
As I have stated repeatedly I doubt that it is significant in this application but bccrane's point about resistance is certainly true. There are force vectors imposing resistance on the traffic. Until we secure an engineering analysis of a particular installation we will not know how much resistance is imposed on the average vehicle and thus will not know if this resistance even matters relative to the momentum of the vehicles (in that application).
The addition fuel that the ferry consumed because of those seagulls is about analogous to the additional fuel that would be used by vehicles cruising along a highway with these turbines installed,eg. so little as to be indistinct and virtually indistinguishable from other sources of resistance.
That is what my intuition tells me too. But, repeating, my position all along now has been that bccrane has a point and that we would need engineering calculations to go from intuition into information. You seem to be trying to convince me that these force vectors are insignificant yet I already hold that intuition. Speak instead to bccrane who appears convinced they are significant.
This entire conversation is wrapped around the presumption that there would be a drop in fuel efficiency of the vehicles travelling along this corridor because of the turbines, which I think is a specious argument to begin with because the effects that it actually has are miniscule, negligible and masked by several much larger factors that affect economy such as a wind speed, directional winds, turbulence, wakes, etc.
Yes the forces are likely negligible. But you cannot simply declare them negligible without studying a specific application. I leave the possibility open with: 'I do not know; we need to analyze specifics now'. You dismiss the possibility intuitively. Bccrane is intuitively convinced it has a significant effect. You two should discuss this.
Someone comes up with a brilliant idea and says let's put magnets on the underside of all vehicles and induction coils in the road bed and let the wasted energy of the vehicle movement generate electricity, do you think that would cause a problem?
That would not be using wasted energy, that would be using the primary use of a vehicle's energy, motion provided by the engine or motor, to generate power. The problem with that scenario would be the vast amounts of metal that would have to be embedded into the roadways. I think it would be impractical at best.
The video showed that a car travelling along a road at 60mph would generate a wind at the turbine site of 12mph and would produce 2.5kW. That is amazing! An argument could be made that the cross sectional area of the fans and the fact that they move out of the way of the pressure wave coming off of the auto would effectively reduce the drag on the vehicle, (remember, these are retrofit around existing poles) thereby making the vehicle more fuel efficient. But I still think that that modest change would be undetectable.
The stream of wind created by the vehicles passing at 70 mpg along the smooth median, let's say is traveling at 40 mph, so all vehicles are traveling with a tailwind and a 30 mph head wind, now place the turbines in and the drag of the generator slows the wind down to 30 mph, now the vehicles are dealing with a 40 mph head wind, you don't think that would reduce their mpg?
I do not think that your numbers are anywhere near real. You are welcome to prove me wrong, I don't really have anything invested. The headwind and tailwind that you propose do not take into account the direction of the waves in the air, which are not directly behind and in front of the vehicle. Each vehicle will push through the air and deflect it in a pattern similar to a wake on a boat (Please see post 9.1.10 ) . So, you would need to do a vector analysis for a first approximation
I think that this is a good use of otherwise wasted energy because the standing wave is generated by the vehicles motion anyway.
The article is a sales pitch that only paints a favorable picture of the VAWT technology. For instance, he talks about the vehicle using its energy to punch a hole through the air and resulting wind has no more effect on the vehicle. The vehicle is displacing the atmosphere and the atmosphere collapses back behind the vehicle at an equilibrium with the fuel/power needed to propel the vehicle forward, anything hampering the displacement outward and inward will cause the vehicle to require more fuel/power to keep the same forward speed.
It's called using examples. The vehicles being used directly as parts of a generator will decrease their mpg, if the same outputs were produced using magnets as with the VAWT why is it assumed that one system would be a drag on the vehicle but the other isn't?
Again the wind speeds were an example, but now in the sales pitch that 12 mph wind was that within 10 feet of the vehicle or out 33 feet (minimum safe distance for obstructions along the road way without a guardrail or barrier).
This sales pitch is a few years old and isn't widely in use yet, if it is such a good idea, why not? If it is as it says, free energy, then the reason would be safety, these machines need to be close and therefore are a traffic hazard.
Aren't the turbines collecting waste energy from the wakes of cars that have already passed the turbine? It shouldn't affect the efficiency of the cars at all.
Imagine putting some kind of turbine on the surface of a lake and then driving a boat past it. The wake is behind the boat and gets to the turbine after the boat is already gone. It doesn't matter to the boat if the turbine is there or not.
The first law of thermodynamics states that energy cannot be created nor destroyed, it can only change forms. Wind energy is being absorbed by the device and converted to electricity and heat. It’s not multiplying the wind that is already there, it’s knocking it down. I hated thermo in college so I’m no authority on the matter, but that seems like it makes sense.
It’s not multiplying the wind that is already there, it’s knocking it down.
It is a resistance that will create a backflow turbulence. This backflow may be entirely insignificant (that I do not know), but it certainly makes sense that it exists. As an analogy, consider a river stream (water flow ≅ air flow). If we place rocks to form a partial dam downstream, that affects the flow of water upstream.
That reminds me of some show I was watching a few years ago where someone made a power generator from a furnace fan stuck in a river in some remote place to power lights in a tavern. I want to say it was some remote place in Norway or something where there was like less than a dozen people. The lights were Christmas tree sting lights. The details are fuzzy... sorry.
Its still about resistance, resistance, resistance and the extra energy you may get from the generator is not enough to match the extra energy needed to overcome the resistance.
It is possible to make a generator out of a lot of stuff. There is no such thing as a free lunch, but if one is utilizing wasted energy that is produced anyway, then that is a net savings of energy.
The same reason you don't find them on high-rises, the towers are designed for wind loads and offer the least amount of wind resistance, wind turbines however use resistance against the wind to over come the load of the generator and use the earth as an anchor through the stout tower and concrete base. A wind turbine on telecom tower would twist the light lattice frame and collapse it.
Resistance to torsion is something any engineer can calculate. It might be a limit for existing towers, but it would be easy to raise torsion resistance on new towers.
My friend was trying, for a little while, to sell towers of the frame type to the US market. Apparently, we all liked the large, white, monopod design batter.
a little off topic, but I've often wondered why electric vehicles don't better harness and utilize all the wasted energy as they're moving down the road to sustain and/or recharge their batteries. solar panels on the top surfaces, magnetos or generators at the axles/wheels, ducted movement of airflow to hidden wind turbines. it seems we already have the technology to implement it.
Again the only thing that would help is the solar panels, everything else will increase the resistance to the motion of the vehicle and the batteries and motors would have to work harder to overcome the resistance, in other words it would be a net loss, if you could get a gain out of any of the things you suggested you would have perpetual motion. Regenerative braking could capture some of the energy back, but never all of it.
While I agree with you that there necessarily will be more wind resistance on the passing cars, I am not convinced that it is significant to them given their momentum. Do you have any supporting engineering analysis for this?
As an example, when you walk past a fan, the breeze you produce will cause turbulence and impose a resistance on the fan. But the resistance is insignificant to the fan's operation.
So yes the resistance is there. But the question is if it is significant.
Yes, because the square inch profile you represent isn't that great compared to the fan, but take a flat panel and move it towards the fan and the pressure increases to the point that before you get close the fan tips over and you feel the same pressure as the fan did before it tips over.
Have you ever drafted a truck, you experience less wind resistance drag and can let up on the accelerator, but the truck is now, in essence, towing you, your saving power but not the truck. Along the highway all the vehicles are traveling in the same direction and therefore the wind they are creating is saving some power for all of them, now the wind turbines to generate a certain power needs say 10 hp, then all the vehicles will lose that 10 hp due to the needs of the generator/s and they're not talking just one but a whole series of them.
This is all besides the point anyway, if all the vehicles are aerodynamic there won't be much of a wind anyways and to save fuel, I would travel in the farthest lane from the wind turbines as would everyone else.
Yes, because the square inch profile you represent isn't that great compared to the fan, but take a flat panel and move it towards the fan and the pressure increases to the point that before you get close the fan tips over and you feel the same pressure as the fan did before it tips over.
So now that we have established that the significance 'depends', we need to apply this to this example. As I noted upfront, I do not know the answer, so the best I can say is that it is possible that the effects of these turbines is negligible in a highway application as described. It is also possible that it is significant.
Do we have a way to determine this other than intuition?
Have you ever drafted a truck, you experience less wind resistance drag and can let up on the accelerator, but the truck is now, in essence, towing you, your saving power but not the truck.
You are explaining basics to me. Have my comments suggested to you that I do not understand the principles at play?
I am interested in how the principles apply to this example. Unless someone can offer engineering calculations, my position is 'I do not know if this is a significant drag on the cars, but it certainly seems possible that it is'.
Well the thing is that the atmosphere is actually quite dense, take for example a lightning strike and the following thunder, it takes only 5 seconds for the sound wave to travel a mile, which is quite impressive since the molecules and atoms bump into each other to keep the wave moving. Now take something like the wind turbine blade a few feet away with the back pressure of the generator, the pressure wave rebounds almost instantly at the vehicles, I would think it would be accumulatively significant.
But there is also a lot of open space in this environment. Contrast an open highway with a tunnel. Putting turbines in a tunnel seems like it would certainly impact the vehicles. I have to wonder about a more open environment like a highway.
Also, note that static signs, cliffs, trees, etc. all serve as a form of resistance on a highway; and they do not give much. I think there might be more freedom here than you think.
The wind (power) generated by the movement of the vehicles is generated by the vehicles whether it is being used or not as a function of moving a mass with a cross sectional area through a fluid. It is not going to affect the vehicle's efficiency by having a wind turbine nearby. It will effect the wind speed and distance traveled before dispersal.
In the example of drafting a tractor trailer, the reason that your car "pulls" along in that bubble behind the tractor trailer is because of the disturbance of the fluid directly behind the tractor trailer that would be there anyway. In effect, the gas mileage increase that one sees is not because the truck is pulling, it is because the fluid in the lee of the trailer is moving at the same speed as the drafting vehicle, thereby causing an increase in efficiency of the car because it does not have to push through the air. That spot in the lee is going to be there whether anybody is dumb enough to hop in or not.
Also, note that static signs, cliffs, trees, etc. all serve as a form of resistance on a highway; and they do not give much.
Yes, but possibly every ten feet and for miles on top of that.
Let's say these turbines produce 3500 watts each. An 8hp 3500 watt portable generator goes through 1 gallon of fuel/hour so if there are 500/mile you'll use 500 gph and for a 10 mile length of 5000 gallons in an hour which is how much the vehicles have to lose to produce that power, granted there maybe 50,000 vehicles passing per hour which comes out to .1 gallons per vehicle, but this is also saying that all vehicles are passing within a few feet of the turbines. (This was a hypothetical example just to give you an idea of how I see it).
It is not going to affect the vehicle's efficiency by having a wind turbine nearby. It will effect the wind speed and distance traveled before dispersal.
Air has a density and when compressed will push back. Compressed air (due to meeting resistance) will push back on the passing vehicles as drag. It is real, I just do not think this will be significant. The more I think about this (intuitively, sans engineering calculations) the less I see it as an issue in this scenario (an open highway). But (intuitively again) I would think it significant if installed in an underground tunnel.
In the example of drafting a tractor trailer, the reason that your car "pulls" along in that bubble behind the tractor trailer is because of the disturbance of the fluid directly behind the tractor trailer that would be there anyway.
I agree. But with these turbines, we are talking about adding a new source of turbulence; new sources to compress the air and create drag.
(This was a hypothetical example just to give you an idea of how I see it).
Understood. Well I guess we will not know until we uncover an engineering analysis of a specific installation which considers available space for compressed air from the vehicles to disburse coupled with the reverse compression resulting from the resistance of the turbines. What will matter are the actual force vectors that directly contribute to the drag on the vehicles (as opposed to those vectors disbursed into the environment). Then, of course, the rest is a simple calculation based on the traffic and average vehicle mix.
The vehicles are not losing power at a rate proportional to the rate of power generated by a gasoline generator, at all. The wind is coming off of the cars no matter if there is anything there to absorb that wind energy or not. The vehicles motion along the highway generates that wind. Once that wind has been generated, it is there. If the wind were bouncing back directly against the vehicle, there would be some moderate effect, but that is unlikely, because the vehicle is moving to generate the wind. A vehicle behind the first will notice a buffeting effect as it approaches the rear of the first, due to the turbulent flow, But it also is generating a wake. It would seem that there would be some optimal placement spacing wise to maximize the energy generated for the speed that the cars are going, but when you get a bunch of cars going at speed, the turbulence of the wakes generated is going to be something like the boat parade pictured below....
Really, it seems that the predominant direction of wind flow would be outward from the center of each lane around automobile traffic, would be highly turbulent, and would not render such vast effects on mileage.
The drag on vehicles is always present. It forms as a function of an object moving through the air or air moving around an object. When in an open space, there is nothing to compress against. When travelling in a tunnel, you get the initial compression of the standing wave when the auto enters the tunnel.
I am referring to additional drag. And there is an additional drag element imposed by obstructions such as signs, cliffs and these turbines even in open space. The question is the significance of the force vectors.
While I doubt these forces would be significant, there is no question that they would exist.
As I noted, this likely would be significant in a tunnel vs. an open roadway.
It is generally known that the flow field around a train is unsteady, turbulent and compressible and in the open air, the compressibility of air is not considered when the Mach number is less than 0.3.
This would suggest to me that the normal highway driver is not going to attain speeds of 0.3 Mach (228mph), and therefore, the effects of these turbines on the fuel mileage is negligible.I would think that the presence of other vehicles would pose a much more substantial impact.
The boat parade isn't a great example of what is happening. But I will go with it as long as you put all those boats moving along side a smooth wall, if you hit it right you could ride the rebound wake of the proceeding boat which would ease the forward movement even though you have to steer slightly into it to keep the straight line along the wall, now let's drive piles every 10 to 20 feet to replicate the turbines along the smooth wall, now you lose some of your forward motion due to all the turbulence and you lose your lunch over the side.
The drag on vehicles is always present. It forms as a function of an object moving through the air or air moving around an object. When in an open space, there is nothing to compress against. When travelling in a tunnel, you get the initial compression of the standing wave when the auto enters the tunnel.
That's also why aerodynamic drafting reduces aerodynamic drag for following vehicles. That's why trains are more aerodynamically efficient; the following cars are in the slipstream.
A horizontal turbine using a ram intake in the vehicle's slipstream could recover energy lost to drag without significantly altering the aerodynamic efficiency of the vehicle. The turbine might introduce turbulence into the slipstream but would not significantly add to the drag.
But that doesn't address the vertical turbines described in the video. The turbines are mounted to existing structures. The turbines are passive collectors; not wind generators. The turbines are not mounted in the path of oncoming vehicles. The vehicle's slipstream dissipates outward from the path of the vehicle.
The biggest problem I see are that the turbines are small generators which means losses due to transmission resistance would limit the cost effectiveness of the installation. These might be useful for powering the lamps they are mounted on but wouldn't be cost effective for generating electricity that could be distributed over any distance.
The boat parade isn't a great example of what is happening. But I will go with it as long as you put all those boats moving along side a smooth wall, if you hit it right you could ride the rebound wake of the proceeding boat which would ease the forward movement even though you have to steer slightly into it to keep the straight line along the wall, now let's drive piles every 10 to 20 feet to replicate the turbines along the smooth wall, now you lose some of your forward motion due to all the turbulence and you lose your lunch over the side.
The problem with that example is that forward motion of a boat must displace an equivalent weight of water. The boat experiences mass effects much more than does non-buoyant vehicles.
The behavior of a boat brought up on the plane is quite different because the boat isn't required to displace an equivalent weight of water.
That's why I said it was a poor example, but I still went with it to point out the turbulence that would be the result of obstacles in the wave pattern.
Do I understand you right in 9.1.15 of placing a horizontal wind turbine on the vehicle? Or was what you meant within a train tunnel? Let's go with the turbine on the vehicle, I believe that would prove my point. If the vawt off the side of the road doesn't affect the vehicles in any way and still produces power, then a turbine placed on the vehicle with the same power production in the higher wind speed shouldn't affect the vehicle either, well we know the answer to that, hell yes it would.
Do I understand you right in 9.1.15 of placing a horizontal wind turbine on the vehicle? Or was what you meant within a train tunnel? Let's go with the turbine on the vehicle, I believe that would prove my point. If the vawt off the side of the road doesn't affect the vehicles in any way and still produces power, then a turbine placed on the vehicle with the same power production in the higher wind speed shouldn't affect the vehicle either, well we know the answer to that, hell yes it would.
Correct, a turbine on or in the vehicle. What I envision is a turbine that uses the pressure differential caused by the slipstream.
The slipstream creates lift on the vehicle because air flowing over the top of a vehicle travels faster than air flowing under the vehicle due to the design of the vehicle. The pressure differential between the top and bottom of a vehicle causes turbulence at the rear of the vehicle. That's also why high speed vehicles can become airborne. Going back to the example of boats, that's how sails work, too. That's also why boat hulls are symmetrical along the length of the keel.
A forward facing ram intake on the underbody and a rear facing exhaust on the top of the vehicle would create a larger pressure differential that could drive a turbine.
I went through the turbine generator combo installed in a vehicle with one of my customers a few years ago. He felt not only could it be used to help the alternator but the excess power could be channeled back into the drive train, by the time I finished explaining why it wouldn't work and for the vehicle a net loss of power, he left pissed at me and never came back.
I went through the turbine generator combo installed in a vehicle with one of my customers a few years ago. He felt not only could it be used to help the alternator but the excess power could be channeled back into the drive train, by the time I finished explaining why it wouldn't work and for the vehicle a net loss of power, he left pissed at me and never came back.
Obviously placing an obstruction in the slipstream would add drag, such as a ram air intake on the hood of a car. But that's not what I am suggesting. What I envision is a turbine driven by suction caused by the slipstream, not by air pressure. That's how aircraft vacuum instruments work.
An underbody spoiler mounted at the front of a car should reduce gas mileage, right? The spoiler protrudes into the air flow so should increase drag. But an underbody spoiler can increase gas mileage because the spoiler reduces drag caused by turbulence.
Doesn't matter where you get the air stream from, the air still has to power the generator against the force of your anchors, the wheels, to match that force the engine has to work harder. The customer was pissed at me because I wouldn't take his money and build him one just as an experiment, he was trying to prove me wrong, I just couldn't see wasting my time and effort and his money for what I knew wasn't going to work. If what he thought it would do, it would've been considered perpetual motion, which is why I know it is a net loss no gain.
Doesn't matter where you get the air stream from, the air still has to power the generator against the force of your anchors, the wheels, to match that force the engine has to work harder. The customer was pissed at me because I wouldn't take his money and build him one just as an experiment, he was trying to prove me wrong, I just couldn't see wasting my time and effort and his money for what I knew wasn't going to work. If what he thought it would do, it would've been considered perpetual motion, which is why I know it is a net loss no gain.
The engine is already transferring power to the air. That power is not being utilized and is already a loss. The idea is to reclaim engine power that is already being lost.
That's the fundamental idea behind the vertical turbines in the video. The vehicles are already losing power to the air. The idea is to reclaim some of that lost power.
What you are talking about is similar to using a fan to drive a wind powered generator. But that's not what I'm talking about.
Doesn't matter where you get the air stream from, the air still has to power the generator against the force of your anchors, the wheels, to match that force the engine has to work harder. The customer was pissed at me because I wouldn't take his money and build him one just as an experiment, he was trying to prove me wrong, I just couldn't see wasting my time and effort and his money for what I knew wasn't going to work. If what he thought it would do, it would've been considered perpetual motion, which is why I know it is a net loss no gain.
Haven't you seen a tarp on a truck lift into a dome? That's caused by a pressure differential. The slipstream on top of the tarp is at lower pressure than air under the tarp. The tarp has little if any effect on the truck's gas mileage. And that pressure differential is still there without a tarp.
Haven't you seen something blow out of a pickup? What usually happens is the object is lifted and the truck drives out from under it. The object typically doesn't travel very far along the path of travel. The object isn't blown back into a following car; the following car drives into the object.
That pressure differential can be great enough to lift a sheet of 3/4 in plywood; not an insignificant amount of power. And that power is lost whether the plywood is there or not. What I am suggesting is that a turbine could be used to reclaim some of that lost power.
To recreate the sensation of letting up on the accelerator of a gas powered vehicle, the generation of power through the drive train drags on the system as would as any system to create power to recharge the batteries while the vehicle is under power.
My neighbor uses solar kilns to dry out lumber. The solar panels weren't quite enough, and there's no electricity service to his property, so he installed vertical turbines, and was in business. Of course, not being close to any traffic, they do require prevailing winds, but he's on a mountain ridge, so most days there is at least a mild breeze.
I used to design wind turbines in my head all the time, even huge ones rotating on circular train tracks. I often imagined putting small vertical axis turbines on the corners of buildings, where there are differences in air pressure (you can almost always feel increased breezes at building corners). The topography of other places seems to magnify breezes as well. There's an off-ramp I know of that always has crazy wind at the bottom of it, and a gas station that for some reason almost always has wind blowing past the pumps at a pretty good clip, even when wind speeds are relatively low elsewhere.
Then my imagination drifted to heat engines, and trying to take energy out of the day and night temperature cycle. You know, let the sun heat water in some kind of collector during the day, and as the air temp goes down at night the differential can allow for energy production with a Stirling engine or something similar. I eventually worked out a constant-flow rotary heat engine in my head, which needed heat applied through coiled pipes on one end and coolness on the other. It was supposed to operate by way of the expansion and contraction of a gas moving through an internal turbine like a jet engine, but in a constant cycle (no intake or exhaust). Always wanted to build a prototype and test it. Never did, though.
S E E D E D C O N T E N T
For those who appreciate clever engineering.
I do appreciate clever engineering but I doubt I will ever understand how it works
You do not give yourself enough credit.
Back when I was a kid a windmill filled the stock tank that we kids swam in out on the prairie.
These are very cool, and the birds think so, too!
Brilliant and it would save a lot of birds.
Nice! I've been wanting to install one at the house for a long time. Hopefully soon. Residential models run from $300 to $3000.
Much better looking, and much more affordable than solar. It looks like a win, win situation.
Question now is if the efficiency makes it a worthwhile purchase.
Wouldn't that be a "Wind, Wind" situation....
Makes me wonder why these things aren’t lining the boardwalks at beach destinations. Plenty of wind and utility lines to tap into there.
Great, increasing the air resistance on the passing vehicles and decreasing their fuel efficiency for a "free" source of energy.
Yeah I wondered about that too. There is a point where the wind resistance will have a significant effect. I just do not know what that point is. Would be interesting to find out.
I wouldn't think it would be real significant in part depending on the drag of rotation, size and location. Which are all variables that can be addressed.
Over all I think this is probably a good thing. It's interesting to see these new technologies being put into place.
I'm enjoying watching the computer age develop.
I remember talking with my late grandmother about her witnessing flight just beginning and I think of her when I see some of the really cool things we have now.
It seems to me it would be less of a problem than passing a tree.
I may be wrong but it seems a stationary object would create more resistance than a mobile one.
you can factor in the resistance made by the vehicles going the opposite direction on the highway as well.
Exactly. It seems to me than any resistance from these spinners would be infinitesimal.
I agree. But the consideration is about adding something new to the equation. These turbines do have a resistance.
But, let me repeat, I do not know if any of this is significant. It may all be entirely negligible.
Well not infinitesimal because the resistance correlates with the energy driving the turbine.
I saw a cool one, it was in Korea I think. In the middle of the highway they made a strip of solar panels. Underneath the raised panels was a walkway and bike path.
They way I look at it, never know until you try. Haha
The energy they are using is the energy of the vehicle after it has already been transformed from the kinetic energy of the moving vehicle to kinetic energy of moving air, to kinetic energy of the physical VAWT and, finally, to the electrical energy by the turbine's alternator...
I used to ride ferries quite a bit, and on every trip across the Sound, there would be several seagulls flying along with the ferry. They got multiple things out of the trip: One would be the food that the people would throw in the air for them, another would be the free ride that they got on the pressure ridge coming off of the bow. They would get in that sweet spot and fly without flapping a bit. The addition fuel that the ferry consumed because of those seagulls is about analogous to the additional fuel that would be used by vehicles cruising along a highway with these turbines installed,eg. so little as to be indistinct and virtually indistinguishable from other sources of resistance.
This entire conversation is wrapped around the presumption that there would be a drop in fuel efficiency of the vehicles travelling along this corridor because of the turbines, which I think is a specious argument to begin with because the effects that it actually has are miniscule, negligible and masked by several much larger factors that affect economy such as a wind speed, directional winds, turbulence, wakes, etc.
The stream of wind created by the vehicles passing at 70 mpg along the smooth median, let's say is traveling at 40 mph, so all vehicles are traveling with a tailwind and a 30 mph head wind, now place the turbines in and the drag of the generator slows the wind down to 30 mph, now the vehicles are dealing with a 40 mph head wind, you don't think that would reduce their mpg?
Let's take the wind out of the equation. Someone comes up with a brilliant idea and says let's put magnets on the underside of all vehicles and induction coils in the road bed and let the wasted energy of the vehicle movement generate electricity, do you think that would cause a problem?
Thomas, I am quite aware of how this works.
Don't think in terms of a single car, think in terms of traffic. The backflow vectors affect the traffic. Vehicle x causes an effect which impacts vehicle y.
As I have stated repeatedly I doubt that it is significant in this application but bccrane's point about resistance is certainly true. There are force vectors imposing resistance on the traffic. Until we secure an engineering analysis of a particular installation we will not know how much resistance is imposed on the average vehicle and thus will not know if this resistance even matters relative to the momentum of the vehicles (in that application).
That is what my intuition tells me too. But, repeating, my position all along now has been that bccrane has a point and that we would need engineering calculations to go from intuition into information. You seem to be trying to convince me that these force vectors are insignificant yet I already hold that intuition. Speak instead to bccrane who appears convinced they are significant.
Yes the forces are likely negligible. But you cannot simply declare them negligible without studying a specific application. I leave the possibility open with: 'I do not know; we need to analyze specifics now'. You dismiss the possibility intuitively. Bccrane is intuitively convinced it has a significant effect. You two should discuss this.
The article has all the numbers needed to draw conclusions.
Why are you ignoring them?
That would not be using wasted energy, that would be using the primary use of a vehicle's energy, motion provided by the engine or motor, to generate power. The problem with that scenario would be the vast amounts of metal that would have to be embedded into the roadways. I think it would be impractical at best.
The video showed that a car travelling along a road at 60mph would generate a wind at the turbine site of 12mph and would produce 2.5kW. That is amazing! An argument could be made that the cross sectional area of the fans and the fact that they move out of the way of the pressure wave coming off of the auto would effectively reduce the drag on the vehicle, (remember, these are retrofit around existing poles) thereby making the vehicle more fuel efficient. But I still think that that modest change would be undetectable.
I do not think that your numbers are anywhere near real. You are welcome to prove me wrong, I don't really have anything invested. The headwind and tailwind that you propose do not take into account the direction of the waves in the air, which are not directly behind and in front of the vehicle. Each vehicle will push through the air and deflect it in a pattern similar to a wake on a boat (Please see post 9.1.10 ) . So, you would need to do a vector analysis for a first approximation
I think that this is a good use of otherwise wasted energy because the standing wave is generated by the vehicles motion anyway.
The article is a sales pitch that only paints a favorable picture of the VAWT technology. For instance, he talks about the vehicle using its energy to punch a hole through the air and resulting wind has no more effect on the vehicle. The vehicle is displacing the atmosphere and the atmosphere collapses back behind the vehicle at an equilibrium with the fuel/power needed to propel the vehicle forward, anything hampering the displacement outward and inward will cause the vehicle to require more fuel/power to keep the same forward speed.
It's called using examples. The vehicles being used directly as parts of a generator will decrease their mpg, if the same outputs were produced using magnets as with the VAWT why is it assumed that one system would be a drag on the vehicle but the other isn't?
Again the wind speeds were an example, but now in the sales pitch that 12 mph wind was that within 10 feet of the vehicle or out 33 feet (minimum safe distance for obstructions along the road way without a guardrail or barrier).
This sales pitch is a few years old and isn't widely in use yet, if it is such a good idea, why not? If it is as it says, free energy, then the reason would be safety, these machines need to be close and therefore are a traffic hazard.
Read the seed.
No.
Aren't the turbines collecting waste energy from the wakes of cars that have already passed the turbine? It shouldn't affect the efficiency of the cars at all.
Imagine putting some kind of turbine on the surface of a lake and then driving a boat past it. The wake is behind the boat and gets to the turbine after the boat is already gone. It doesn't matter to the boat if the turbine is there or not.
The first law of thermodynamics states that energy cannot be created nor destroyed, it can only change forms. Wind energy is being absorbed by the device and converted to electricity and heat. It’s not multiplying the wind that is already there, it’s knocking it down. I hated thermo in college so I’m no authority on the matter, but that seems like it makes sense.
It is a resistance that will create a backflow turbulence. This backflow may be entirely insignificant (that I do not know), but it certainly makes sense that it exists. As an analogy, consider a river stream (water flow ≅ air flow). If we place rocks to form a partial dam downstream, that affects the flow of water upstream.
Damn those laws of thermodynamics!
Like Heinlein said "there is no such thing as a free lunch" (TINSTAAFL).
Beside Airport runways would be a great place for these things
Quite possibly.
Also they could perhaps end up lining places like Subways and other transportation tunnels even inside of pipelines.
That reminds me of some show I was watching a few years ago where someone made a power generator from a furnace fan stuck in a river in some remote place to power lights in a tavern. I want to say it was some remote place in Norway or something where there was like less than a dozen people. The lights were Christmas tree sting lights. The details are fuzzy... sorry.
Its still about resistance, resistance, resistance and the extra energy you may get from the generator is not enough to match the extra energy needed to overcome the resistance.
True I was thinking about that, but new ways of reducing resistance have and are being developed every day.
Such as magnetic lifting and balanced computer designed and built bearings and drive shafts offering very little resistance.
It is possible to make a generator out of a lot of stuff. There is no such thing as a free lunch, but if one is utilizing wasted energy that is produced anyway, then that is a net savings of energy.
Perhaps the best aspect of this tech is its dispersion. A turbine on a telecom tower means less load on the grid. Multiply that by all the towers.....
The same reason you don't find them on high-rises, the towers are designed for wind loads and offer the least amount of wind resistance, wind turbines however use resistance against the wind to over come the load of the generator and use the earth as an anchor through the stout tower and concrete base. A wind turbine on telecom tower would twist the light lattice frame and collapse it.
Resistance to torsion is something any engineer can calculate. It might be a limit for existing towers, but it would be easy to raise torsion resistance on new towers.
My friend was trying, for a little while, to sell towers of the frame type to the US market. Apparently, we all liked the large, white, monopod design batter.
a little off topic, but I've often wondered why electric vehicles don't better harness and utilize all the wasted energy as they're moving down the road to sustain and/or recharge their batteries. solar panels on the top surfaces, magnetos or generators at the axles/wheels, ducted movement of airflow to hidden wind turbines. it seems we already have the technology to implement it.
Again the only thing that would help is the solar panels, everything else will increase the resistance to the motion of the vehicle and the batteries and motors would have to work harder to overcome the resistance, in other words it would be a net loss, if you could get a gain out of any of the things you suggested you would have perpetual motion. Regenerative braking could capture some of the energy back, but never all of it.
While I agree with you that there necessarily will be more wind resistance on the passing cars, I am not convinced that it is significant to them given their momentum. Do you have any supporting engineering analysis for this?
As an example, when you walk past a fan, the breeze you produce will cause turbulence and impose a resistance on the fan. But the resistance is insignificant to the fan's operation.
So yes the resistance is there. But the question is if it is significant.
Yes, because the square inch profile you represent isn't that great compared to the fan, but take a flat panel and move it towards the fan and the pressure increases to the point that before you get close the fan tips over and you feel the same pressure as the fan did before it tips over.
Have you ever drafted a truck, you experience less wind resistance drag and can let up on the accelerator, but the truck is now, in essence, towing you, your saving power but not the truck. Along the highway all the vehicles are traveling in the same direction and therefore the wind they are creating is saving some power for all of them, now the wind turbines to generate a certain power needs say 10 hp, then all the vehicles will lose that 10 hp due to the needs of the generator/s and they're not talking just one but a whole series of them.
This is all besides the point anyway, if all the vehicles are aerodynamic there won't be much of a wind anyways and to save fuel, I would travel in the farthest lane from the wind turbines as would everyone else.
So now that we have established that the significance 'depends', we need to apply this to this example. As I noted upfront, I do not know the answer, so the best I can say is that it is possible that the effects of these turbines is negligible in a highway application as described. It is also possible that it is significant.
Do we have a way to determine this other than intuition?
You are explaining basics to me. Have my comments suggested to you that I do not understand the principles at play?
I am interested in how the principles apply to this example. Unless someone can offer engineering calculations, my position is 'I do not know if this is a significant drag on the cars, but it certainly seems possible that it is'.
Well the thing is that the atmosphere is actually quite dense, take for example a lightning strike and the following thunder, it takes only 5 seconds for the sound wave to travel a mile, which is quite impressive since the molecules and atoms bump into each other to keep the wave moving. Now take something like the wind turbine blade a few feet away with the back pressure of the generator, the pressure wave rebounds almost instantly at the vehicles, I would think it would be accumulatively significant.
But there is also a lot of open space in this environment. Contrast an open highway with a tunnel. Putting turbines in a tunnel seems like it would certainly impact the vehicles. I have to wonder about a more open environment like a highway.
Also, note that static signs, cliffs, trees, etc. all serve as a form of resistance on a highway; and they do not give much. I think there might be more freedom here than you think.
The wind (power) generated by the movement of the vehicles is generated by the vehicles whether it is being used or not as a function of moving a mass with a cross sectional area through a fluid. It is not going to affect the vehicle's efficiency by having a wind turbine nearby. It will effect the wind speed and distance traveled before dispersal.
In the example of drafting a tractor trailer, the reason that your car "pulls" along in that bubble behind the tractor trailer is because of the disturbance of the fluid directly behind the tractor trailer that would be there anyway. In effect, the gas mileage increase that one sees is not because the truck is pulling, it is because the fluid in the lee of the trailer is moving at the same speed as the drafting vehicle, thereby causing an increase in efficiency of the car because it does not have to push through the air. That spot in the lee is going to be there whether anybody is dumb enough to hop in or not.
Yes, but possibly every ten feet and for miles on top of that.
Let's say these turbines produce 3500 watts each. An 8hp 3500 watt portable generator goes through 1 gallon of fuel/hour so if there are 500/mile you'll use 500 gph and for a 10 mile length of 5000 gallons in an hour which is how much the vehicles have to lose to produce that power, granted there maybe 50,000 vehicles passing per hour which comes out to .1 gallons per vehicle, but this is also saying that all vehicles are passing within a few feet of the turbines. (This was a hypothetical example just to give you an idea of how I see it).
Air has a density and when compressed will push back. Compressed air (due to meeting resistance) will push back on the passing vehicles as drag. It is real, I just do not think this will be significant. The more I think about this (intuitively, sans engineering calculations) the less I see it as an issue in this scenario (an open highway). But (intuitively again) I would think it significant if installed in an underground tunnel.
I agree. But with these turbines, we are talking about adding a new source of turbulence; new sources to compress the air and create drag.
Understood. Well I guess we will not know until we uncover an engineering analysis of a specific installation which considers available space for compressed air from the vehicles to disburse coupled with the reverse compression resulting from the resistance of the turbines. What will matter are the actual force vectors that directly contribute to the drag on the vehicles (as opposed to those vectors disbursed into the environment). Then, of course, the rest is a simple calculation based on the traffic and average vehicle mix.
The vehicles are not losing power at a rate proportional to the rate of power generated by a gasoline generator, at all. The wind is coming off of the cars no matter if there is anything there to absorb that wind energy or not. The vehicles motion along the highway generates that wind. Once that wind has been generated, it is there. If the wind were bouncing back directly against the vehicle, there would be some moderate effect, but that is unlikely, because the vehicle is moving to generate the wind. A vehicle behind the first will notice a buffeting effect as it approaches the rear of the first, due to the turbulent flow, But it also is generating a wake. It would seem that there would be some optimal placement spacing wise to maximize the energy generated for the speed that the cars are going, but when you get a bunch of cars going at speed, the turbulence of the wakes generated is going to be something like the boat parade pictured below....
Really, it seems that the predominant direction of wind flow would be outward from the center of each lane around automobile traffic, would be highly turbulent, and would not render such vast effects on mileage.
The drag on vehicles is always present. It forms as a function of an object moving through the air or air moving around an object. When in an open space, there is nothing to compress against. When travelling in a tunnel, you get the initial compression of the standing wave when the auto enters the tunnel.
Here
is a paper on train and tunnel effects.
I am referring to additional drag. And there is an additional drag element imposed by obstructions such as signs, cliffs and these turbines even in open space. The question is the significance of the force vectors.
While I doubt these forces would be significant, there is no question that they would exist.
As I noted, this likely would be significant in a tunnel vs. an open roadway.
From the Science direct link above:
This would suggest to me that the normal highway driver is not going to attain speeds of 0.3 Mach (228mph), and therefore, the effects of these turbines on the fuel mileage is negligible.I would think that the presence of other vehicles would pose a much more substantial impact.
The boat parade isn't a great example of what is happening. But I will go with it as long as you put all those boats moving along side a smooth wall, if you hit it right you could ride the rebound wake of the proceeding boat which would ease the forward movement even though you have to steer slightly into it to keep the straight line along the wall, now let's drive piles every 10 to 20 feet to replicate the turbines along the smooth wall, now you lose some of your forward motion due to all the turbulence and you lose your lunch over the side.
That's also why aerodynamic drafting reduces aerodynamic drag for following vehicles. That's why trains are more aerodynamically efficient; the following cars are in the slipstream.
A horizontal turbine using a ram intake in the vehicle's slipstream could recover energy lost to drag without significantly altering the aerodynamic efficiency of the vehicle. The turbine might introduce turbulence into the slipstream but would not significantly add to the drag.
But that doesn't address the vertical turbines described in the video. The turbines are mounted to existing structures. The turbines are passive collectors; not wind generators. The turbines are not mounted in the path of oncoming vehicles. The vehicle's slipstream dissipates outward from the path of the vehicle.
The biggest problem I see are that the turbines are small generators which means losses due to transmission resistance would limit the cost effectiveness of the installation. These might be useful for powering the lamps they are mounted on but wouldn't be cost effective for generating electricity that could be distributed over any distance.
The problem with that example is that forward motion of a boat must displace an equivalent weight of water. The boat experiences mass effects much more than does non-buoyant vehicles.
The behavior of a boat brought up on the plane is quite different because the boat isn't required to displace an equivalent weight of water.
That's why I said it was a poor example, but I still went with it to point out the turbulence that would be the result of obstacles in the wave pattern.
Do I understand you right in 9.1.15 of placing a horizontal wind turbine on the vehicle? Or was what you meant within a train tunnel? Let's go with the turbine on the vehicle, I believe that would prove my point. If the vawt off the side of the road doesn't affect the vehicles in any way and still produces power, then a turbine placed on the vehicle with the same power production in the higher wind speed shouldn't affect the vehicle either, well we know the answer to that, hell yes it would.
Correct, a turbine on or in the vehicle. What I envision is a turbine that uses the pressure differential caused by the slipstream.
The slipstream creates lift on the vehicle because air flowing over the top of a vehicle travels faster than air flowing under the vehicle due to the design of the vehicle. The pressure differential between the top and bottom of a vehicle causes turbulence at the rear of the vehicle. That's also why high speed vehicles can become airborne. Going back to the example of boats, that's how sails work, too. That's also why boat hulls are symmetrical along the length of the keel.
A forward facing ram intake on the underbody and a rear facing exhaust on the top of the vehicle would create a larger pressure differential that could drive a turbine.
I went through the turbine generator combo installed in a vehicle with one of my customers a few years ago. He felt not only could it be used to help the alternator but the excess power could be channeled back into the drive train, by the time I finished explaining why it wouldn't work and for the vehicle a net loss of power, he left pissed at me and never came back.
Obviously placing an obstruction in the slipstream would add drag, such as a ram air intake on the hood of a car. But that's not what I am suggesting. What I envision is a turbine driven by suction caused by the slipstream, not by air pressure. That's how aircraft vacuum instruments work.
An underbody spoiler mounted at the front of a car should reduce gas mileage, right? The spoiler protrudes into the air flow so should increase drag. But an underbody spoiler can increase gas mileage because the spoiler reduces drag caused by turbulence.
Doesn't matter where you get the air stream from, the air still has to power the generator against the force of your anchors, the wheels, to match that force the engine has to work harder. The customer was pissed at me because I wouldn't take his money and build him one just as an experiment, he was trying to prove me wrong, I just couldn't see wasting my time and effort and his money for what I knew wasn't going to work. If what he thought it would do, it would've been considered perpetual motion, which is why I know it is a net loss no gain.
The engine is already transferring power to the air. That power is not being utilized and is already a loss. The idea is to reclaim engine power that is already being lost.
That's the fundamental idea behind the vertical turbines in the video. The vehicles are already losing power to the air. The idea is to reclaim some of that lost power.
What you are talking about is similar to using a fan to drive a wind powered generator. But that's not what I'm talking about.
Haven't you seen a tarp on a truck lift into a dome? That's caused by a pressure differential. The slipstream on top of the tarp is at lower pressure than air under the tarp. The tarp has little if any effect on the truck's gas mileage. And that pressure differential is still there without a tarp.
Haven't you seen something blow out of a pickup? What usually happens is the object is lifted and the truck drives out from under it. The object typically doesn't travel very far along the path of travel. The object isn't blown back into a following car; the following car drives into the object.
That pressure differential can be great enough to lift a sheet of 3/4 in plywood; not an insignificant amount of power. And that power is lost whether the plywood is there or not. What I am suggesting is that a turbine could be used to reclaim some of that lost power.
Tesla reclaims energy when coasting.
To recreate the sensation of letting up on the accelerator of a gas powered vehicle, the generation of power through the drive train drags on the system as would as any system to create power to recharge the batteries while the vehicle is under power.
Yes, regenerative braking.
It'll have to spin in the opposite direction to work in the US.
My neighbor uses solar kilns to dry out lumber. The solar panels weren't quite enough, and there's no electricity service to his property, so he installed vertical turbines, and was in business. Of course, not being close to any traffic, they do require prevailing winds, but he's on a mountain ridge, so most days there is at least a mild breeze.
So it seems only a matter of time before someone merges this technology
with this
I'll take two please !
I used to design wind turbines in my head all the time, even huge ones rotating on circular train tracks. I often imagined putting small vertical axis turbines on the corners of buildings, where there are differences in air pressure (you can almost always feel increased breezes at building corners). The topography of other places seems to magnify breezes as well. There's an off-ramp I know of that always has crazy wind at the bottom of it, and a gas station that for some reason almost always has wind blowing past the pumps at a pretty good clip, even when wind speeds are relatively low elsewhere.
Then my imagination drifted to heat engines, and trying to take energy out of the day and night temperature cycle. You know, let the sun heat water in some kind of collector during the day, and as the air temp goes down at night the differential can allow for energy production with a Stirling engine or something similar. I eventually worked out a constant-flow rotary heat engine in my head, which needed heat applied through coiled pipes on one end and coolness on the other. It was supposed to operate by way of the expansion and contraction of a gas moving through an internal turbine like a jet engine, but in a constant cycle (no intake or exhaust). Always wanted to build a prototype and test it. Never did, though.