Prototype piezoelectric road could generate power by simply sitting there
By Darren Murph 
posted December 13th 2008 1:20PM
posted December 13th 2008 1:20PM
By sitting there and getting ran over by motorcars, that is. In an effort to best other power-generating highway options that involve solar panels and enlarged blender arms, Britain's Environmental Transport Association is looking to test a prototype highway that's embedded with piezoelectric crystals. Essentially, the process would work much like the power-generating Tokyo station floors we saw earlier this week; each car that squishes a crystal would contribute a tiny bit of energy, and the collective effect could be enormous. In fact, it's estimated that a single kilometer of roadway could generate 400-kilowatts of energy, or enough to power around eight small cars. And we're no rocket scientists (nor physicists), but we're assuming these whiz kids already made sure these magic crystals weren't friction-generating, too. Right?
Regardless of friction, any surface that harnesses energy from cars is going to require more energy from those cars. With a piezoelectric system like this, the energy comes from "squishing" the crystals-- essentially making the road a little softer. softer surfaces require more energy to traverse.
This idea makes much more sense with pedestrians and bikes, because at least then the root energy source isn't burning fossil fuels.
your talking about a tiny, tiny amount of "squish"
the amount of additional energy consumed would be far less then what you would lose from having your tires a few PSI low.
But would it squish more than it normally would? Asphalt does have a little give to it anyway, so it might not be a problem. It gives me an idea though, why not piezoelectric tires? That way you'd generate power without needing a special road. It'd probably work even better in those honey comb tires, more material to bend and flex.
Maybe if you drive on concrete roads... Sadly enough, most roads are pebble bed, sand, asphalt, sometimes they even replace the sand with dirt (maybe not sometimes, more like always in the places i live). If they don't already have enough rolling resistance, i don't know what does. In fact, most piezos don't change shape that much, and when they are already less than a millimeter thick, it results in negligible dimension loss. Yes, road surface changes efficiency, but as pointed out above, the biggest source of energy loss due to rolling friction is in the tires being under inflated.
you. It's still stolen energy from me. It's not right.
basroil:
My tires are not underflated. I have an air compressor just for that purpose.
And besides, even if they were, it still wouldn't be right to steal energy from me. It'd be like saying a gas station rigged their pumps to give out 0.9 gallon of gas per gallon charged because "people are driving gas guzzlers anyway".
Unbelievable...
ROADS ARE GETTING "SQUISHED" ANYWAY!
Robert Abramson is right, this does just take energy from the cars due to rolling fricton. Sure there already is rolling friction, but this ADDS to that friction. It's simple conservation of energy.
Conservation of energy means that you will never get back as much energy as you lose from the extra squish.
Thank you moose, and everybody else that understand the conservation of energy and the loss that accompanies transfer of energy from one form to another. I tried mightily to defend the laws of nature and economics in the last piezoelectric topic [ http://www.engadget.com/2008/12/11/piezoelectrics-installed-in-tokyo-railway-station-floors-generat/ ], but my argument still wound up being "rebutted" by someone calling me a fool.
Robert, pedestrians and bikes are still powered by the human body, which is ultimately powered by food. Increase human energy output requires an increase in food intake. You can't get energy for nothing. It's simply more efficient to go from Sun->Solar Panel->Electricity than from Sun->Plant->Human->Bike/Foot->Electricity.
I'm going to charge them for using my cars fuel.
There's no such thing as free energy...
Guys,
All I'm getting at is that using this for serious power generation would be silly-- it would be far more efficient to run a gasoline generator.This technology could be useful for running extremely low-power appliances like traffic signals where the energy required from each passing car is negligible, but anything more would be extremely wasteful; and since the root power source is gas anyway, it's not particularly green.
Tobias,
I understand that human beings ultimately draw their power from the sun-- that was exactly my point. A sidewalk using this technology is essentially a way to harness some solar energy, while the same thing on a road would be harnessing fossil fuel. I also understand that solar panels are more efficient than this; I was just making a point about the "green-ness" of this particular proposition. But that said, this would work in situations without any sun, and seems like it might be cheaper.
@Tobias:
it could mean an increase in food intake or hopefully just less fat people
@Dr. Funky
Right now heat is being produced on our roads as the tires run over it. If we used this technology instead, less heat would be produced and a little electricity. This could result from the exact same amount of fuel. There is no fundamental theoretical problem here.
There is no break of the laws of nature. Might be of economics, but that doesn't interest me as much.
It seems to me that everyone has missed the point. Roads already "squish", but that energy is wasted. On this road, you actually yield electricity from the squishing of the road. My gosh, what you're saying is like telling people that gas mileage can't be increased, because of the laws of thermodynamics. Here's a hint, the laws of thermodynamics only prevents efficiency from reaching 100%, but you can still increase efficiency on an inefficient design.
@ Tobias.
This is silly, "Sun->Plant->Human->Bike/Foot->Electricity". Human/automobile energy being calculated here is power that is being generated by the normal actives of people, capturing that energy is what's efficient. The real question is how much these piezoelectric panels costs, this is the same reason why solar energy is still an insignificant part of out energy supply, because the cost and energy that is going into it is more then what you get out in a reasonable amount of time.
Using your logic for petroleum:
""Sun->Plant->Animal->(millions-of-years-underground)->Drilled->Processed->Transported-to-market->combusted in engine"
Point being, its not about absolute efficiencies that are important its whats available and accessible; petroleum is probably the most inefficient, but its readily available and cheap. "Conservation of energy" is a high-school level concept that isn't relevant everywhere, people cars move around in this world; if that energy can be captured in a cost effective manner then its worth investigating.
First off, physicists: The laws of thermodynamics only apply to closed systems. There is no closed system known to man. A road most certainly isn't.
I'd be sceptical about these piezo elements - the inventors would need to show that the energy created does not require the cars to burn more fuel. There are arguments for and against above, many of them valid, but it seems like this would be something to be determined empirically rather easily. Just measure it. I can't imagine it wouldn't require more fuel to be burned but why not provide some cold, hard numbers. If it does require more fuel the question is how much, and the efficiency of generating energy this way could be determined from that. I am sceptical - it probably won't add up.
Dr. Funke: Cycling requires more food intake? You must not be living in America! Though I'd suggest that wiring up the fitness centers would be more efficient... put those treadmills and other machines to good use and make them generate electricity.
In regards to friction. The surface will likely be asphalt and there should be absolutely no increase in rolling resistance, the piezoelectric plates will likely be underneath the surface. The material is usually combined with the piezoelectric crystal, the expansion and contraction is done on a microscopic scale, there is negligible 'softness', and shouldn't effect the efficiency of the vehicle traveling over it.
The real questions is cost. The installation and maintenance of these plates would be expensive. The real question is how cheaply can make and deploy them. Many natural sources, like sugar crystals, have been shown to show piezoelectric effect, so there is hope for cheap piezoelectric materials. As with all technology you have to start somewhere.
Robert Abramson:
You are entirely correct, essentially this road is absorbing energy from the vehicles that traverse it; in turn, the vehicles will need to generate more energy to travel the same distance.
The offshoot of this is twofold:
A) The energy is harnessed from gasoline and diesel powered vehicles, therefore there will be more emissions.
B) More fuel used means that the energy gathered in this manner comes at the expense of those traversing these roads.
This seems like a poor way to make money off of roads and a terribly inefficient way to generate power. At best this can be seen as an alternative to tolls.
We need to see the cost of the piezo-electric road compared to the current cost of laying current road material. If the cost of the Piezo roads are higher, Big Oil is going to KILL THIS DEAD.
More along the like of if this product is too expensive compared to generating electricity the old fashioned way, common sense will kill it dead.
Having said this, I'm glad products like this are being researched. Even if this one costs too much to justify it, soon enough there will be cheaper ones.
Oh, and I just started designing this in my head, thinking about it. Wouldn't it be something like a slab of concrete over something like springs? And when the car moves over it, the weight pushes it down, and then when it moves off the springs push it up? And that movement would generate the electricity. I've not looked into it, but that is how I'd design it.
And if you get _just_ the right combination of cars of exactly the right weight and wheelbase moving at exactly the right speed and spaced apart by the precisely correct amount, your roadway ends up flipping cars over each other like leapfrog. Fun times!
Run buddy, Big Oil is going to get you, and he's BIG
Jinto, congratulations; you've just described the basics of piezoelectricity.
I can't help but notice the number of "experts" in the laws of thermodynamics in these comments. Honestly, people, these are researchers, not a single man wearing a tinfoil hat. I think they know a little more about physics than you do, so let them do their jobs, alright?
Actually big oil would LOVE this sort of thing. The energy is STILL being produced by fossil fuel .. the car would obviously have to burn up extra fuel as it contributes energy to the "crystal crushinG" .. which would result in slightly more fuel being burned per car than if it were a solid road. This is actually a very inefficient way of generating electricity, so actually more fossil fuel will be burnt because of this. Government likes it because they dont have to tell anyone they're raising taxes (though actually the effect is the same). Big Oil would love it because the energy is being produced from oil .. inefficiently at that!
@ Johna S,
Thank you! I made a similar comment about how ridiculous this process is on the Tokyo subway thing.
PEOPLE! Energy doesn't come from nowhere! It cannot be created, and it cannot be destroyed; only transferred (and nearly always without 100% efficiency).
Cars use gas to move. Running over these crystals will only make it harder for the car to move, which will make it use more gas. Plus, a good portion of the extra gas that is used is immediately converted to heat-energy (coming off the engine), thus being wasted, as is a lot of the friction energy that the crystals absorb.
If you want to store and use otherwise wasted energy, you basically need to trap heat. Most of our wasted energy is in the form of heat. Whether it's the rays from the sun that we aren't catching, or the refrigerator blowing hot air into your air-conditioned house in the middle of the summer. Or even the wind power that we aren't using. What makes wind? HEAT! (or more specifically, the MOVEMENT of heat).
@dg
"Energy doesn't come from nowhere! It cannot be created, and it cannot be destroyed; only transferred (and nearly always without 100% efficiency)."
Err... you've just contradicted yourself! If energy cannot be destroyed, and it's rarely transferred 100%, then it has to go somewhere. It *is* transferred perfectly, always - look up the law of conservation of energy - it's just not always transferred where you want it, which makes something inefficient.
Read what Zach said. This is using wasted energy. Not turning roads into balloons.
Next one of you guys will make a lolpiezo that says "Im in ur roadz, reducin ur cars eficiency"
Just put these on the downhill slopes when the cars would be braking anyway. Helps braking and generates power. Fixed it for you.
Just like public transportation!
Better yet, let's have a generator dyno on every highway, and before you can get on, you have to sit on a dyno for 5 minutes on full throttle.
seriously. If counties or countries or whoever builds these insists on getting energy from the cars that travel over their roads, id rather pay a toll equivalent to what id lose in gas mileage driving over a "magic road;" it could then go to purchase energy much more efficiently than 30% ice * whatever losses from generation and transmission. Bonehead politicians do shit like this just so they can get most of the voting populous to think they're being green. like they give a shit.
Or install this in the beds of Nympho couples... Should generate a good 1.21 Giggawatts every night!
You mean...
Giggidy-giggidy-giggidy watts?
Ummm... this sounds like the most inefficient way of generating electricity ever proposed.
I LOVE your line there HITSTHINGS.... hilarious....
This will cost tax payers dearly; then they charge excessive tolls for "maintenance." Sounds like a scam.
Ever been on the IL toll roads? They needed a way to pay for its construction. The booths were supposed to be temporary...
Free energy for everyone!
It's likely that this won't show up as lost fuel economy for the individual. They will just show the total that it has produced and everyone will be amazed. Average Joe is going to see it as free energy even if it would waste more energy in form of fuel burned by the wasteful car engines.
...getting RUN over... Grammar is your friend!
The key technology questions are, how hard are they to dig up, can it be done on a dark night, and what's the resale value?
Pick axe, yes if you don't mind risking a toe, and with very little market, negligible.
What do the squiggly lines in the road stand for (in the picture)?
Indicates the area of a pedestrian crossing.
You mean it isn't just me this time?
of course energy can't be had for free, or come from no where.
This would be stealing slight amounts of energy from the cars driving over it.
Essentially this would be petroleum powered electricity.
The roads already steal slight amounts of energy from the car when the pavement flexes. This is more akin to regenerative braking, in that it's harnessing wasted energy.
Regenerative braking is teriffic because you are conserving the energy that would be wasted while the car is slowing down anyway. It's not desirable to add any more drag to cars that are cruising down the road.
Now adding this to off-ramps and places where cars are always decelerating anyway, that is where this technology should be used if anywhere.