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110 Comments
- cmyk, on 12/13/2008, -6/+27There's no such thing as a free lunch; it simply drains the energy from the work the car does. So you use more fuel. Fantastic.
- cheezintern, on 12/13/2008, -3/+21The road will create greater resistance. Therefore you will need more fuel to drive the same speed. It's like the difference between racing slicks and little donut tires. One will get piss poor gas mileage and the other will get great mileage.
- ArrenV, on 12/13/2008, -3/+18I wonder what the cost and structural integrity would be of these?
- itspuddingtime, on 12/13/2008, -1/+13the only question here is whether the piezoelectric generators will deform to a greater or less (or same) degree than asphalt itself does already. We don't know the answer from the information given in the article.
- inactive, on 12/13/2008, -10/+21Um that means using more fuel?
- WELLDOITLIVE, on 12/13/2008, -3/+13There is no such thing as free energy. Basic engineering principles say that this is a bad idea.
- Harabeck, on 12/13/2008, -3/+12Something like the alternator actually takes energy out of the system that is powering the car. This system would capture otherwise completely wasted energy.
- tonmil, on 12/13/2008, -2/+10What does it do to rolling resistance and, therefore, MPG?
- belumaves, on 12/13/2008, -3/+11while it is true that there is no free lunch (first law of Thermo, you can't win) what this system does is reclaim energy already lost by the car. the car has no change in energy state, the road will still support it, the rolling resistance will be about the same, so you as a driver see no change.
The change is what happens to that energy leached off your car due to rolling resistance. Typically the blacktop squishes a small amount, the strain energy becomes heat, and it is radiated out into the air. what this does is take what would be heat and instead make electricity. the heating will probably be less (but we are talking about tiny values) and there will of course be losses in the system (second law of thermo, you can't break even, except at absolute zero) but in the end less energy is going to waste. - tomz17, on 12/13/2008, -0/+7Yeah, the fact that it is not EXPLICITLY mentioned in the article is very fishy...
As other posters have pointed out, the amount of deformation relative to asphalt is what's important here.
I'd bet that the deformation of this piezo material is greater than that of asphalt, otherwise the company would have specifically said otherwise in their marketing material.
P.S. Another concern is how well this ages, how much it costs to install, and how easy it is to repair/patch/digg up, etc. I suspect it really isn't worth it once you look at the entire picture! - yuanzhoulu, on 12/13/2008, -2/+9@harabeck
it has to, it's a simple energy conservation issue. ever so slight microscopic deformations are required in the material in order for it to harvest that kind of energy, and so many of them that it adds up. - Mizzark, on 12/13/2008, -3/+9The car drawings blew me away.
- Harabeck, on 12/13/2008, -4/+10Did you even read the article? The system would coat a surface being driven over and capture the energy that way, it wouldn't be reducing the efficiency at all.
- jjason1985, on 12/13/2008, -1/+7A priest and a rabbi walk past a playground. The priest says " lets f*ck them". The rabbi asks "...out of what?"
Parasitic energy generation - the PARASITIC part means you take out energy from the vehicles otherwise used for forward motion. - cmyk, on 12/13/2008, -2/+7@Harabeck
I *seriously* doubt asphalt or concrete warps as much as this material does. In fact, I'll bet, the more this technology warps, the better the results, and the more gas it steals from the cars.
Do cars lose energy when they drive over typical roads? Of course. But with this system, you're still losing energy to friction, *plus* the added deformation drain. - belumaves, on 12/13/2008, -3/+8no... the road will deform, there is no getting around it, all loaded materials strain slightly, but normally that strain energy becomes a slight elevation of temperature, this takes that energy and makes electricity that can be used instead of wasted heat.
- WELLDOITLIVE, on 12/13/2008, -4/+8Exactly. When you deform this material, your car sinks down a bit. Not much, but it takes work to get back up to the same level and you are doing it over and over again. Your gas mileage goes down.
This is a stupid idea, you are basically stealing gas from people. - bigdoug2005, on 12/13/2008, -2/+6For this to work it would have to make the road flex less and convert that same energy that would be used for flexing to electricity. If the road still flexes the same amount and it produces electricity at the same time, more energy must be lost by the car.
- cmyk, on 12/13/2008, -0/+4If this is the case, the company sure is doing a piss poor job of explaining that.
- postitnote, on 12/13/2008, -0/+4But then that means our roads are less efficient than they should be. Why would we not choose to improve the efficiency of the paving material instead?
- da_bradler, on 12/13/2008, -0/+4I have a hard time believing anything could be cheaper then smashed up rock and tar oil.
- yuanzhoulu, on 12/13/2008, -0/+4your math is *****.
- IFEice, on 12/13/2008, -1/+5My major is electrical engineering, and that made my day. Apparently any idiot can write an article and ignore the laws of energy conservation.
- LightUrple, on 12/13/2008, -0/+4Someone had suggested that in an online physics journal a couple of years ago. My TA sent us all a link to the article with an explanation of why this doesn't work and is just bad physics. Basically by adding wind turbines to the side of the highway, you would create more air resistance as you drive by. Before your car was just pushing air out of the way, but now it would be pushing turbine blades. This would slow your car. Just a little, but it would. You probably wouldn't even notice it.
The energy produced by the turbines would be coming from you having to burn more gasoline, so in effect the drivers would all be paying for this new "clean" "free" energy source (which in reality would be neither clean nor free). - itspuddingtime, on 12/13/2008, -0/+3finally, someone who understands. thank you
- hpymondays, on 12/13/2008, -2/+5Great idea, except for... cost. I suspect this great idea ignores the cost of implementation and maintenance. I believe the benefit will be negligible relative to the enormous cost of installing such a technology in a meaningful way and maintaining it. Nonetheless, they should give it a limited trial.
- Harabeck, on 12/13/2008, -0/+3Neighborhoods in Mexico have speedbumps all over the place. Man that is annoying as hell.
- WELLDOITLIVE, on 12/14/2008, -0/+3You wonder where he got the hour from, did he just make a dumbass assumption? Why not per minute or per day or year?
- pixelguru, on 12/13/2008, -3/+6Bridges and overpasses flex a surprising amount under load. I've sat in traffic and watched the movement of large pieces of concrete at the joints. I know some of that movement is "healthy" for the structure, but if any excess can be harvested, I'm all for it since there's a LOT of energy being transmitted there. I doubt it would be economically practical to retrofit existing structures, but any new structures might be able to integrate some energy capturing technology for relatively little additional cost, or a cost which would pay for itself in x# of years.
- mikeophile, on 12/13/2008, -0/+3Seems kind of stupid to embed the roads to capture the force of vehicles when you could harness the energy being wasted through the shock absorbers of individual vehicles. Right now, shock absorbers just turn the undesirable up and down motion of cars into heat.
- silvershadow21, on 12/13/2008, -1/+4"150kW of electricity per hour"? That doesn't even make sense. A watt is defined as 1 joule/sec, so the unit kJ/sec/hour doesn't have any meaning at all. Maybe they meant just 150kW (seems unlikely to me), or 150kJ per hour.
- yuanzhoulu, on 12/13/2008, -0/+3there actually isn't that much heat in the road. ever tried to touch a road after a car whizzed by it? do you feel any difference?
- barc0001, on 12/13/2008, -0/+2I saw a similar system where they have a "speedbump" that gets depressed flat as the car rolls over it to run a piston on a mechanical generator. Obviously since doing that will leech kinetic energy from the car dramatically, the plan is to only put them in places that vehicles would be having to slow anyway, like off-ramps, etc.
- Harabeck, on 12/13/2008, -1/+3The author made a little snafu:
http://en.wikipedia.org/wiki/Watt-hour
"Note that the kWh is the product of power in kilowatts multiplied by time in hours; it is not kW/h." - LJSeinfeld, on 12/13/2008, -5/+7Article doesn't say if the surface of the piezoelectric material deforms any more or any less than the roadway already does. And you don't know either.
You are basically pulling your answer out of your ass.
For all we know it could make the road surface harder thereby decreasing the amount of rolling resistance and your car would get better mileage. - itspuddingtime, on 12/13/2008, -1/+3it does not "coat" the roadway, these generators have some depth to them and must be cut into the asphalt surface.
- xbanned, on 12/13/2008, -3/+5It seems that when putting goals (find sources of clean energy), the private sector can find innovative ways to meet these goals. Global warming awareness and energy crisis did their job.
- inactive, on 12/13/2008, -1/+3I don't know. Energy is constant and doesn't come out of thin air. What's used to produce energy in this cames seems to come from an increased resistance for the vehicles travelling over it, meaning that what they in reality have is a gasoline/diesel generator. If they somehow "harvest" the noice and turn it into energy, then it would be fantastic.
diggydougies idea about putting something like this in front of traffic lights is good though. A lot of energy is wasted and turned to heat through breaking anyway. To harvest energy from speedbumps is also a good idea. - t05ter, on 12/13/2008, -2/+4@cmyk: You're 100% right. Not only does it drain kinetic energy from your car, but it's a sure thing that the efficiency of collection isn't 1 to 1. This means that not only are they stealing your gas, but they're wasting some in the process.
Of all the schemes that take energy from the streets, the best ones are those that use pedestrian side walks. We're too fat already anyways, might as well take some calories and convert it into grid power. - Itsaah2o, on 12/13/2008, -0/+2I wonder if you put a similar type of system right in front of a stop light in a high speed area, if the friction caused by the tires and road could produce more energy?
- js281, on 12/13/2008, -0/+2Harabeck works for this company or something?
- inactive, on 12/13/2008, -0/+2"1km of a railroad can produce up to 150kW of electricity per hour"
writers should stick to writing and out of science. ... and learn the difference between power and energy - diggydougie, on 12/13/2008, -1/+3The only way that I see to get energy from traffic without decreasing MPG would be to somehow get the energy from decelerating cars at traffic lights. The cars need to stop anyway so that really would be free energy (except for hybrids). But how would it be done? Drive into a "bin" which uses the momentem to drive a generator? Or how about giant nets or cables like on aircraft carriers?
- Ramble, on 12/14/2008, -0/+1Uhhh, yeahh. If you could go ahead and not comment, that'd be great.
- js281, on 12/13/2008, -0/+1A better idea in my opinion is wave power (i.e. waves in the sea), it is much beefier in terms of energy generated than wind farms, and unlike these road based generators, the energy would be genuinely free.
- js281, on 12/13/2008, -0/+1Generators on speed bumps is a great idea. Someone could push that to governments and make a lot of money.
- meddelem, on 12/18/2008, -0/+1the concept is correct . the application is all wrong.
- Gareth321, on 12/13/2008, -1/+2@dyvvyd
You need to RTFA. Currently the energy is being lost by the deforming road without any energy harvesting devices. Your car already loses a tiny bit of energy. They are proposing placing these devices to harness that energy that would have otherwise been lost. It's pretty damn straight forward. - dyvvyd, on 12/13/2008, -2/+3Before you go calling someone names, why don't you make sure you know what you are talking about.
His statement is accurate. There is in fact no "free lunch". Any energy you pull from the vehicles will have to be replaced to keep the vehicles moving at the same rate.
If you feel like calling someone an idiot, take a look in the mirror. The phrase would seem to be a lot more accurately placed that way. -
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