Clogged highways and frustratingly waiting while your gas needle plummets to empty usually doesn't conjure up thoughts of
green, but it seems like these very roads could become the source of a lot more energy. Several recent student designs have proposed that major roadways be retrofitted with various forms of
wind energy collection devices, ranging from overhead turbines that collect energy from quickly-moving cars below to barrier panels (pictured after the jump) that harness the wind from closely passing vehicles moving in opposite directions. Ideally, the wind energy could then be sent back out to the grid to power nearby communities, light-rail transportation systems, or even
intelligent billboards. Of course, most of these ideas are still in the research phase, and even if proven feasible, we can't imagine the up-front costs (or inconveniences of installing these things) to be minor, but we're sure that government subsidies should be able to to lend a helping hand.
Read - Barrier panel prototype, via
InhabitatRead - Overhead turbine design, via
Inhabitat
posted April 30th 2007 10:04AM
Not to mention that more modern cars are inherently more aerodynamic as some of the most cost efficient development dollars spent for fuel economy are those spent making a car more aerodynamic, creating less drag.
So what? More aerodynamic cars = less air turbulence = less "wind" attribuatable to the cars themselves.
Dumb idea for that reason, unless the freeway happens to be in a windy location.
I think this is an extremely good idea...
When I clicked the link to this article, I was expecting something about using the center median as a location for standard 50+ meter wind turbines. What a let-down this article was.
For starters, the turbines in the center concrete barrier are a horrible safety issue. Crashing into one of those barriers at 65 would almost always be fatal. The current ones are smooth and hard so that your car can slide along them instead of getting caught up in them (Imagine hitting a telephone pole on the interstate rather than a concrete barrier). Scoop out the center of them and all of the sudden there is a something for the car to catch on which will make many accidents fatal when a normal barrier would have allowed the passengers to walk away.
@Dirty Sloth
1.8 MW is a rather large turbine. What was pictured above would be (optimistically) 1/100th of that size and would require heavy traffic at high speeds. Heavy traffic tends to slow traffic down and light traffic wouldn't cause enough wind to keep the turbine spinning. I can't see any advantage of this over simply placing a moderately sized 1+ MW standard turbine in the center median. They would both cost about the same, and one would generate 100 times the power and wouldn't require any traffic - just a steady wind. You are comparing a 300,000 dollar contraption that would power no more than 4 homes to a modern windmill that can power thousands of homes (albeit for a few million dollars).
In short, while wind energy is an excellent source of power, the proposals in this article are utter crap. Where are the proposals to put windmills on skyscapers, Tidal energy generation, etc?
"government subsidies"?
Who do you think pays for the public roadways now? Uh, the government. No subsidies required, just tax and spend! Perhaps local gov't could get in the business of selling the electricity they generate to offset the cost of installation or to lower their own energy bills.
If there is any extra resistance it will be greater on the cars that push more air, another reason mot to drive an SUV or anything with high wind resistance.
Boston has a wind turbine situated next to a major highway:
http://www.eere.energy.gov/windandhydro/windpoweringamerica/images/newengland/22_ibew.jpg
The idea here is not to "save" energy but to turn "waste" kinetic energy into electricity.
Whether powered by gasoline, hydrogen, or superpowered squirrels, there will be vehicles traveling at fairly high speeds along our highways (and railways etc, as Balogh noted). As they go, they will push a good deal of air out of their way. That temporary artificial wind is a "waste by-product" of vehicle motion. Harnessing it with wind turbines won't increase the drag on the vehicles any more than driving past the billboards etc. which are already there... or at worst, like driving past dense shrubbery. You won't notice any effect on your mpg, that's for sure.
For the same reason, placing wind turbines along our freeways and railways is one of the very few places (tops of tall buildings is another) where we can be fairly sure that large-scale wind harvesting will have virtually no additional environmental impact: the freeway/railway/tall building already exists, already alters local wind patterns/animal mobility/runoff etc. We might as well make it begin to pay back some of its carbon footprint.
(I share Brent, Trojan etc.'s concern about durability: maybe locate them at places where the barriers are rarely or never hit, or not even needed, e.g. the insides of curves? Or attach stacked narrow vertical-cage turbines to the big-diameter existing sign posts?)
Birds will be safe: it's the "fan"-style windmills that kill birds. "cage"-style turbines, whether curved-blade or straight-blade, don't kill birds.
You do not need any fluid dynamical analysis of this system to understand that it is a net loss of energy, only a basic understanding of thermodynamics.
You will by definition expend more fuel energy than is recouped by such a device, increasing the emissions per unit of energy of the entire system (car + windmill). The cleanliness of such a device is limited by (that is, has a lower limit that is defined by) the cleanliness of the cars powering it. This is a great idea if you work for big oil.
@ chris
"They wouldn't slow down the cars passing under or around them; the engine moves the car, the car moves the air, the air moves the turbines. The highway wind is the inadvertent result of an energy expenditure and it would be a pretty passive collection process."
It's quotes like this that make engineers cringe, science teachers cry, and makes me realize that our education system *is* as bad as people make it out to be these days. Please, if you have kids, don't build them a treehouse.
I think it does take a careful analysis of the overhead scheme to decide whether the inevitable energy loss due to drag can be captured in a way that makes the scheme desirable. Suggestions that it is immediately obvious from first principles that it is a net loser are themselves a bit scientifically naive. It sounds like cdgent knows the score...although a citation or two to professional papers with analyses would help us all out. If it is a loser in capturing wasted vehicle energy, install it higher to avoid increasing drag and capture even more ambient wind energy. But I think dwaede has the best insight...it is simply a great place to put wind towers for urban areas to be near demand and thus reduce distribution losses, cause little more visual clutter than existing highway signage, and little more noise pollution than existing highway noise. Maintenance concerns are a downside...shutting down highways for installation and maintenance could be problematic. Maybe just vertical towers in highway ROWs instead. Worthy of a study to see if the dollars work out.
Indeed, living in NY, those tunnels are like large pistons, the train just constantly pushes air forward! And most already run on electricity. Imagine if the whole subway system was completely self-efficient and off the grid? Blast your ACs kids! (just kidding, that's bad for the environment too :P )
bobartig
"They wouldn't slow down the cars passing under or around them; the engine moves the car, the car moves the air, the air moves the turbines. The highway wind is the inadvertent result of an energy expenditure and it would be a pretty passive collection process."
It's quotes like this that make engineers cringe, science teachers cry, and makes me realize that our education system *is* as bad as people make it out to be these days. Please, if you have kids, don't build them a treehouse.
If you claim to be educated like you make your quote seem, you would realize to capture wind energy off of a car and inadvertently cause more drag on the car, you would need the turbines to be extremely close to the vehicle.
I am in Texas, and there are certain laws that require signs over the freeway to be high enough for semis to pass under. Should these turbines be in place, the only vehicle if any that would suffer is big rigs, but they already expend such a large force pushing through the wind that this small drag coefficient would be insignificant.
And I doubt these would be placed at 10 yard intervals for miles at a time. Probably would cause the same drag problems as current signs above the freeway. So if you have problems with these turbines, you should really vocalize the removal of all signs above freeways and any overpasses too.
Nate, David-
In a closed environment such as a subway the losses in this system are even more obvious. Why do you think all seriously high-speed subway proposals discuss partially evacuating the tunnel to reduce drag? Its bad enough that the train has to accellerate the air mass after each stop and deal with friction losses from the walls, this idea would simply make it worse.
Also, David, you may want to check wikipedia for 'perpetual motion machine' before making comments like that one.
Fair enough, I think I may have inadvertantly professed to know something about this subject, and went beyond my usual amount of blabbin. Good to know someone in here knows though. Just want to keep the subject optimistic.
Hmmmm.....so if the cars go faster (burn more fuel) these egg beaters generates more electricity...hmmmm.....and if more people drive more miles, not cut back on fuel consumption these things generate more electricity.....and best yet, if we convince those on using efficient public transportation to drive their cars....even more electricity generated....ingenious!
what about similar turbines on the vertical poles in between the two directions? won't cars from either direction make the turbine spin even faster?
I think most of you are missing the big picture.
First, we here in the US will not stop driving and are increasing our highways each year. In 2004 the USDOT estimated we drive 1.7 Trillion miles each year!! We are driving gas vechicles now. There is a waste of energy if its not captured. It only goes to pushing that single vechicle. You are going to drive anyway. If one is to imagine a future where all energy is created as "green" as possible then hybrids, Etc will be the future, but for now lets turn a negative into a positive! Millions start driving each year so the increase in "potential local (US) energy production" only increases and becomes more consistant. As for drag the device will have to be a certain distance away before USDOT would sign off so you'll be gone before your wind even reaches it. Imagine a world where just driving to work helps to produce electricity!!
First these type of windmills are much less efficent than standard blade types. As high as they would need to be over Semis they would get NOTHING from most smaller cars and little from large SUV's. Look at the wind farms near Palm Springs, Ca. They are there becasue the wind blows there. Wind DOES NOT blow down a highway. Even with traffic. If you "think" it does go try flying a kite next to one. The minor passes of gusts will toss it around but not make it fly. Now go try to fly a kite near the Palm springs windfarm. I agree anyone who thinks this is a good way to spend money needs to start strongly competing for the Darwin awards. If there WAS a way to harness wasted car energy it would be a way to recoupe the energy wasted by cars sitting at stoplights. Not easy but a lot more energy to be had there IF there was a way to tap it. If windmills were (and I think they will be one day just because we need to) put anywhere wind studies supported them we would make the most cost effective wind genrator sites there. To many people hate the way they look. These people are killing the planet as bad as anyone. I have seen people fight like heck to stop windmills in areas they need them. Bottom line there ARE better ways to get energy but as long as there is oil to sell they (people who sell oil) are gonna keep all other energy means down. Bill
OMG !!!! Isn't it too far fetched. I totally agree that it is gonna give the vehicles a drag in opposite direction, forcing engines to burn more fuel. Lets see if we can have an estimate of generation, from a machine like that ..
We would have to work around the problem of transmission loss inefficiency. Currently, transmission loss would make it impractical to run conduit along hundreds of miles of highway.
That is an utterly stupid comment. If transmission loss was an issue, how do we have electricity sent to our homes? There is already a great deal of electric running along countless miles of highway for streetlights and other nearby electrical items. Even if this power was enough to simply power the streetlights it would be well worth it. People need to stop thinking that little ideas like this need to save the world. You have to take baby steps.
In order to capture any useful amount of energy the turbines would have to be very close to the cars, which in doing so would indeed increase the drag on them - if the cars move the turbines then the cars must be doing work on them! Consider the limiting case where instead of a turbine some distance above the car you have a wheel which spins when it touches the top of each passing car. It's fairly obvious that this is going to increase the friction on the car. Now move the wheel away a bit, and replace it with a turbine blade. It's exactly the same principle, you've just inserted air in the middle and replaced one frictional transfer (car-wheel) with two (car-air-turbine). Basic thermodynamics then tells you that in order to extract any amount of energy from either system you must be increasing the work done by the cars, and because of the other losses (frictional losses, inertia of turbine, etc.) this will be greater than the energy you can extract.
The people who think this would work are probably the same ones who'd believe they could extract "wasted" energy from their hot water pipes. I mean- they're hot anyway, right?
Treetrunk, actually it does work like that. Your comments are assuming that no air is moving in the first place, which is wrong. Example, if someone was boiling a pot of water on their stove, the steam would be rising no matter what else was going on. If you put a fan blade over the steam, it would move due to the steam, and would not effect the boiling water in the least.
Yes, you cannot just generate energy from nothing; however, if the work is already being performed, as in the case with the car slicing through the air, then you aren't creating any additional drag on the car. Your example of the train is a completely different scenario; in that case you're talking about something on the order of a yard of clearance on either side. The car scenario would have a much great differential since it would have to be tall enough to allow semis to pass through. Also, a train tunnel is surrounding a train up, down, left, & right. This scenario would be only on the top and bottom, which would allow for passing of air on either side. Although there would be some effect on the car, it is so minimal that the calculation would be an exercise in futility. It's called fluid dynamics, check it out.
I know what I'm talking about, I have a degree in Mechanical Engineering from the University of Illinois (one of the top engineering schools in the world). I currently work for the largest supplier of nuclear power plants in the world, so I have quite a bit of experience when it comes to electricity generation.
they sam-
the argument that wind turbines kill "piles" of birds is the dumbest thing i've ever heard. There is no basis for this argument whatsoever. House cats kill thousands of times more birds than windmills ever will. I don't hear people complaining about house cats.
Yes, I've thought about this idea for awhile. In fact, that's why my son sent me the link. My basic research with curretn pma technology and vehicle use, this is a sure cure for not only maximizing our re-use of energy but minimize greenhouse gases. A Subway trains use about 5 megawatts and the tunnels installed with appropriate draft catches would be able to recapture most of the wasted enegy moving the air to move the train. sections of heavily trafficed areas could supoport miles of hooded tunnels mazimizing the collection system, minimizing road maintaneance and filtering toxic gases.
It would be easy for a city like toronto to putout more than 1000 megawatts and now we're talking nuclear power plant equivalents.
You see gas isn't used to move the car arlong the road, it's used to move it through the air. That displacemnet and replacement of the air is an energy source. Newtons for every action there is an equal and opposite reaction says that this reactive energy is just as much as the initial enegy (well minus the friction on road and tire).
so why doesn't some one tell the president..or the prime minister?.
because I don't know how to get my head that far you their ass to speak to them man to man.
Your comments: I only hope that your joking Terry. If you actually think this will
work...... Yes gas has to move a car thru the air but it also moves it down the road and up hills and where ever it needs to go among doing dozens of other things. When a car goes by you on the road it pushes you away but then the backdraft of many cars sucks you back in. Thus it would push then pull IF you could get a windmill close
enough. Since they have to be at least 13 plus feet to clear Semis thus cars would not affect them at all (the overhead ones) the center
barries gears and drivetrains would eat anything there. A large cost for nothing. I said this before and I will say it again. Let YOUR tax
dollars pay for this IF you are dumb enough to think it will work and you may live off ONLY the power it generates. Hope you like the dark.
This was proposed by school students who have not had to many physics classes yet obviously. Even cars on the road with hybrid electric drivetrains that use the elecric part during braking to add back to the battery only gain small amounts and thats with a direct SOLID connection. Throw a commpressable (as air is) 5 to 10 foot wind barrier (distance between vehicles and turbine blades. (more would be needed for safety)) and you aint barely getting squat. If you think otherwise your brains came from someones squat session. Bill
"The air is being moved by the cars anyway"
It doesn't work like that. The moment you stick something in the moving air, you increase the drag on the car, because the air "being moved anyway" by the car will push against it. That's why a fast-moving train makes a noise when it suddenly hits a tunnel or goes past another train.
U don't want to know how much poweloss there are out there in the powergrids! We're talking percentages!!!
Quote: "Transmission and distribution losses in the USA were estimated at 7.2% in 1995 [2], and in the UK at 7.4% in 1998."
U know how much of worh that is in dollars? More than my salary.
I'm not sure how much drag on cars will be added by such turbines, but it's sure some will.
That's because the wind moved by the cars will be slowed down by the turbines, taking energy from it.
So the same car, and the following, has a slower wind to move, so they need more fuel.
That's thermodinamics as some said: you're transferring energy from the engine of the car to the turbines, not converting a pure wasting process like braking.
Another interesting point someone raised is how high the turbines need to be, in order to let big trucks pass.
So probably only big trucks will move the turbines, making them rotate only a fraction of the time.
My comments certainly do not assume no air is moving in the first place, I don't know what gave you that impression.
Steam rising from boiling water is not an appropriate analogy as here the driving force is not the pan but the difference in densities between the steam and surrounding air. Therefore it is not surprising that there is no effect on the pan! To compare to the car imagine the pan were in fact (as the car does to air) "pushing" a column of steam upwards, either through air or through turbine + air. Adding the turbine in the path of the steam would (in this hypothetical example) increase the work required by the pan to move the steam.
That "work is already being performed" is beside the point- yes, there is already drag due to moving the air, but if you insert something in that air close enough to experience force then its absolutely obvious that you're going to disrupt the flow, increasing the drag on whatever's moving through it. Action and reaction- if the air exerts a force on the blade then the blade exerts one back on the air and thus back on the car.
I believe the train example to be appropriate as in order to experience any useful force I imagine the turbines would need to be "within a yard or so" of passing vehicles. The idea that a "real" system would require the turbines to be much further away is a BAD thing for your argument, as at that kind of distance the forces must be tiny. I acknowledge the difference in that a tunnel encloses the train on all sides, however, my point was more the effect of hitting the mouth of the tunnel, as an object near to the train. You chose to ignore the example of another train, which doesn't enclose the train on all sides.
"Although there would be some effect on the car, it is so minimal that the calculation would be an exercise in futility"
I disagree entirely. It might be possible to construct a system such that there was only a minimal effect, however, the force on the turbines would also be minimal! We're talking about driving a heavy lump of metal connected to a generator that's going to oppose motion as soon as any current is drawn. It's going to take a sizeable force to do so which will mean a sizeable drag on the cars. Distributing the waste into apparently "negligible" chunks doesn't make it disappear- you'd be better off running an engine off the extra fuel this would waste and running a generator off that directly!
That's great. I'm an engineering student at probably the most famous university in the world. I'll leave you guessing which one :)
Haha, well I guess we're peers then. I wasn't too fond of MIT, where I assume you go. If it isn't MIT, you are sorely mistaken about the "famousness" of your engineering school.
Anyway, I believe you're making a mistake in your assumptions. Of course the energy has to be accounted for, but it is not necessarily all from one car. In my steam/turbine example, there is no way more work has to be performed by the pot of boiling water. The steam would just rise through a turbine, and it would turn ever so slightly. To INCREASE the speed, you'd have to make it a contained pressure vessel, much like a power plant, which would end up exerting forces on the system.
In our example of the car and the road, we have a completely wide open system. The turbine blades on the side of the road or on top would be extremely lightweight, and would generate very low levels of electricity. I agree that the generation would be a very low level; however, if you had a high traffic area (LA for instance) and put some lightweight turbines there, you would generate enough to power something, say a street light. On the smallest of scales a car might do a wee bit more work, but you're talking an immeasurable scale. You make it sound like the cars will go from 30mpg to 20mpg because of these things. We're talking more like 30.0000000000 to 29.99999999999. I don't even think it would be that much even. The grade/banking of a road would have a much more significant impact.
Technically, you are correct in saying it will have some effect; however, you right now sitting at your computer are having a gravitational effect on the cars passing by your house, but we don't include that in our calculations, now do we?
The point is that it is in fact a cool novel idea. It might not even be cost effective. But it most definitely should not be shot down because you think it will start slowing down traffic. If you truly think that is the case, you should consider all the objects currently blocking clear air-flow on interstates: road signs, barriers, reflectors (the bottom of the car is most important since it is so close to the surface), and of course other vehicles.
Also, I'd bet my life that you are a Computer Science or Electrical Engineering student. That would explain your complete and utter non-understanding of common sense.
In conclusion, we both agree that it would generate a very small amount of energy; however, that is the idea. You generate the small amount a few hundred thousand times, and you have a mediocre amount of electricity. This wasn't meant to power a city. You are trying to apply basic laws of thermodynamics as if you are using a small controlled system. If you want to get that technical, you should consider that the temperature of the air a car is going through would have a gigantic impact when compared to the small amount of these wind turbines.
I didn't claim it would be "all from one car", but what difference does it make? Whether it comes from a big effect on one car or a smaller effect on a hundred, the net effect is the same (in fact the combined losses of many smaller transfers are likely to be higher than one big one).
As I explained above, in the steam/turbine example I believe you're correct no more work would be performed by the pot WHEN THE DRIVING FORCE IS THE DIFFERENCE IN DENSITY. However, as I also explained above, this is NOT an appropriate comparison as for the car the driving force moving the air is not the difference in density but the physical movement of the car. Therefore, replace the steam with some gas of similar density to air, which will not therefore rise by its own accord, and PHYSICALLY MOVE IT, eg. with a piston. Inserting anything in the flow of gas will exert a force back upon it, locally increasing the pressure around the object, and providing more resistance to the flow. Therefore to move at a given speed the force back on the piston (or car) MUST increase. That it's an open system (thus meaning some of the moving air can "bypass" the obstruction) doesn't matter- any air that does this behaves as it would were the obstruction not there, and obviously EXERTS NO FORCE ON THE TURBINE. The air which DOES hit the turbine will behave as described above, increasing the force back on whatever's moving it.
I don't think "very low levels" of electricity is really what's envisioned here. If all you want to do is power a street light, just stick a solar panel on it! Solar isn't the cheapest or most efficient of technologies, but compared to this idea it probably wins on both! It certainly wins on simplicity, reliability (no moving parts) and visual impact. I disagree that I'm "trying to apply basic laws of thermodynamics as if I'm using a small controlled system" - the fact that its an open system and that other variables exist doesn't matter when you're only changing one, the same rules apply!
Nope, my university doesn't like people to have a "complete and utter non-understanding of common sense" (not terribly elegant use of grammar!) so their Engineering course is a Masters in which you study all branches of engineering for two years before specialising. I'm specialising in Chemical and Electrical so this kind of thing (fluid dynamics + electricity) fits me pretty well!
The LA traffic comment by JayBandit cracked me up. I am guessing he has never drove out there too much LOL. Its a terrible parking lot more than it moving.
For the people who think we hate change or are afraid of different things its simple. This is about #453,567,987 down on the list of ways to create useful energy at a reasonable cost. What if the cars and the wind were going in opposite directions?? The connection from a cars wind and the blades is soooooooooo inefficent to be remotley effective. For a fraction of the cost large PROVEN designs can be placed where the wind blows naturally but people cry when there precious coast lines get windmills proposed. These are the problem.
To all the peole who think that technology has made turbine designs better to work in this situation like this try to remember that they are using that tech in windmills now where the wind DOES provide useful power and its still not enough. Onboard regenerative braking is far superior for current hybrids. As for "other" cars... Capturing energy from them would require a fifth wheels to be added that could touch the road and creat drag or a mechanism attached to the driveshaft to create drag on downhills and then store it for other use. Not cheap. We could save a lot more energy than these would generate if we simply started adding funky (think exaggerated) but functional aerodynamics to cars that suffer from being built like a brick syndrom. To move them through the air easier would save far more than the puffs would spin a generator. Its not that this would not work. Its jsut it would be terribly expensive and make so small an amount of useable power. Bill
No price is to high for ecologically safe technology. I don't care how much it costs. Would anyone rather continue to accelerate global warming just to save a bit of money?...Of course. I don't know why I asked. I hate people sometimes....Rant over
The big problem I have with so called green technology is the slow pace at which it proceeds. There has been zero emissions technology for years, yet there is no zero emission vehicle, excluding bikes and electric vehicles. The car companies won't get off their *sses and stop perpetuating oil dependence. I think they've worked out a deal or two with big oil. Again, people piss me off.
what about . .now i'm just *asking* .. . what about the possibility of putting turbines _on cars_? . .. i mean . .what if, while a car was moving, it just charged cells from a moving turbine (like the alternator charges a battery?) would there be so much drag that it would create a bad level of efficiency . .
i took a couple of mechanical engineering classes in college but i just dont remember the rules of efficiency...
just imagine . .it *would* be cool... if you could get a turbine that didn't cause drag somehow? (hide the half of it that would be moving the same direction as teh vehicle...)?
paz,
j
It sounds to me like a lot of people are saying that these would only work properly in heavy traffic, and that wouldn't work because heavy traffic usually moves slower. Okay. It sounds to me like we just need to wait for a time seen in I, Robot when cars are controlled by AI. It seems like that would prevent heavy traffic from slowing down, since the slowing down usually occurs from people braking because of something the idiot in front of them is trying to do, and a good AI system could solve that problem.
Then, we'd have fast-moving heavy traffic, and it would be a perfect time to implement these turbines.
No, you Gomers! This highway wind farm isn't meant to harvest the wind energy generated by passing cars! It is meant to harvest the wind generated by mother nature. Your rich friends are the ones who don't want the traditional wind mills offshore! They have little desire to look at them while on vacation during the summer months! So that brings us to THIS compromise. Sounds fine to me as long as these things have a SAFE mode that applies a fixed brake once the system encounters a problem, and nothing can fall on anyone riding in a passing car below.