Clean Power

Published on December 16th, 2013 | by James Ayre


Generating Electricity From The Weight Of Cars & Pedestrians

December 16th, 2013 by  

An interesting new means of generating “sustainable” energy has recently been jumped on by researchers in Mexico — utilizing the vehicular flow of car traffic to drive bellows that then power a turbine which generates electricity.

“This is a technology that provides sustainable energy and could be implemented at low prices, since it’s a complement of already existing infrastructure: the concrete of streets and avenues,” states Héctor Ricardo Macías Hernández, the developer of the system.

“He added that at a global level there are no records of similar projects, with exception of an English patent, but with the difference that in the European country piezoelectric floors are used, which are too expensive for developing countries,” a news release about the development states.

Mexican entrepreneurs developed a system capable of using the vehicular flow to generate electric energy. Image Credit: Investigación y Desarrollo

Mexican entrepreneurs developed a system capable of using the vehicular flow to generate electric energy.
Image Credit: Investigación y Desarrollo

The technology consists primarily of an integrated ramp-step (elaborated with polymeric material similar to the ones used in the manufacture of tires) that rises to about five centimeters above street-level — as the impact and weight of the vehicle crosses this ramp-step, pressure is exerted on the bellows that lie below.

Investigación y Desarrollo provides more:

The bellows contain air that is expelled at a certain pressure through a hose; later, this element travels to a tank where it is compressed and relaunched to an electricity generating turbine. Macías Hernández also said that the accumulation of electric energy is proportional to the flow of cars over a determinate spot; however, in places with low vehicular flow, several ramp-steps could be placed to multiply the impact of every individual vehicle.

The developer added that the technology could also be implemented in places with high pedestrian flow. This way, the steps of the people would generate electricity according to the laws of gravitational energy, and this principle could be implemented in places like the subway. This development is translated in a source of sustainable energy that implies a low execution cost.

Macías Hernández also noted that the support of the Mexican Institute of Industrial Property (IMPI) was essential to the development of the new technology.

Check out our new 93-page EV report, based on over 2,000 surveys collected from EV drivers in 49 of 50 US states, 26 European countries, and 9 Canadian provinces.

Tags: , , ,

About the Author

's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.

  • Stanley Fricke

    well roads get hotter when cars drive on them, check the track temperature before during and after a fornula 1-race. bellows seem a bit pennalizing with out knowing more but certainly using a passive solar heat system would steal the heat energy with out much to steal from the cars that -by the way are not steel wheels on steel tracks – isn’t already given up by the cars, the fact that most cars have shock absorbers already is conclusive evidence that cars are pounding the road with every mile they travel. piezoelectric surfaces give up millivolts per micro strain, now ask your selves what is the tolorance on the roundness of a tire?… is it one millimeter over a 180degree rotation of the tire? In other words pezio would work on the road without impacting what is already impacted! Now if you ever have the pleasure of driving the length of the Pennsylvania Turnpike you would agree that someone should pay for crapy roads but also until cars look more like trains the piezoelectric road would not rob gas mileage from todays cars. QED

  • Joe

    This is actually should be illegal, as it is a Blatant Theft of energy from cars!! In other words, this is a blatant fuel theft from cars!!

  • Arndt Ritter

    While vampire energy can be bad, you could use this where energy is otherwise wasted as heat. For example, a downhill segment where drivers are braking anyway. I don’t see why people are instinctively dismissive of it.

    • Andrew Snow

      In theory this would work in the types of places you mention. But installing it into the road and maintaining it would probably be rather expensive. There is a much cheaper, and more efficient way to take advantage of the same “wasted” energy. And you can get it TODAY.

      Every hybrid and electric vehicle on the market “collects” this energy. When the car slows down, it operates an electrical generator to charge a battery. When you accelerate again, it uses the energy stored in the battery to help push the car.

      This is more efficient for many reasons, one of which is that it can be used every time the car slows, not just when you are in the correct spot on the road.

      And, it is much easier to implement reliably. You don’t have water, sand, salt and snow constantly being pounded into the machinery by every tire.

  • Hans

    As others have stated: this will lead to extra fuel usage of the cars. Since car motors are already very inefficient and there are the additional conversion losses of the ramp system, this is a very inefficient, and thus polluting way of generating electricity. It is also a form of stealing fuel. Only when this system is installed at a place where cars have to stop anyhow it makes sense. Even then it makes only sense if the majority of cars uses a fuel based motor, hybrid and electric cars can recuperate their kinetic energy while breaking much more efficiently as this dead-born technology.

    I vote for a physics 101 course for all energy bloggers.

  • mk1313

    If the idea could be implemented using piezoelectric materials such that the strain and not a physical movement generated the power (so that the cars don’t have to generate additional energy to move across the raised road sections thereby decreasing their mileage) this might work. Otherwise the only real implementation is where energy loss is desired such as speed bumps.

    • Bob_Wallace

      The law of conservation of energy tells us that the energy to produce the electricity has to come from somewhere.

      If the system is producing no electricity except when a vehicle is moving across it then we have a good candidate for what is supplying the energy input.

      • mk1313

        The energy is already being put out to move the car. If it can be harvested without degrading the cars performance that would be good. If it can’t it is a net loss and should not be done except where that loss is intended, as in the aforementioned speed bumps. I can envision a piezoelectric strain harvesting mechanism that would not degrade the vehicles performance whereas a bellows mechanism entails the car having to push harder to effectively go uphill to pump the bellows. Yes the car is the source of energy the question is can some of that energy be harvested without affecting the performance of the vehicle? Somewhat analogous to thermoelectric modules being placed on exhausts to extract some of the energy of the waste heat.

        • Bob_Wallace

          Since we can’t create energy out of nothing it must be the case that some of the kinetic energy of the car is being used.

          If the car is moving downhill toward a stop sign then there’s no important loss to the car. The car’s energy would otherwise be dissipated by brake heat.

          Outside of that unique situation the energy loss will have to be replaced by the car engine/fuel.

          • mk1313

            Bob,you are already putting energy into the pavement by 1) vibration as you roll over it (think of being able to feel a heavy truck roll by) and 2) deforming the pavement slightly as the vehicle rolls over it. That energy is currently lost. With piezo effects some of that currently wasted energy might be harvestable. Since you are harvesting energy already being lost you are not having a negative effect on the energy flow of the vehicle. Yes the energy would be small for any 1 vehicle that could be recovered from that wasted energy but the millions of cars might make it feasible. Google piezoelectric energy production.

          • Andrew Snow

            Yes, energy is lost to the pavement flexing. But, have you ever ridden a bicycle on a dirt road? If the dirt is hard, you have to pedal a little harder than on pavement. If the dirt is soft, you have to pedal much harder. The more the road surface gives under the tires the more energy you have to put out to move forward.*

            Now, energy by DEFINITION is a force action over a distance. A piezoelectric cell can NOT put out electrical energy if it does not deflect. And, the upper limit on the electrical energy it can put out is the distance it deflects times the force applied to it.**

            Further, if you add piezoelectric elements to a road, you don’t eliminate the deflection that is there today. What ever you put over the piezoelectric cells to protect them, and whatever is under them to support them will still deflect.

            So, the piezoelectric road will give more under the tires than pavement. So, just like driving on a softer road, your car’s engine will have to work harder on the piezoelectric road.

            Now some technical blather:

            * By “give” I mean the road surface deflecting without returning 100% of the energy. I understand it’s not necessary how hard the road surface is, but how much hysteresis it has. But, it is common for softer road surfaces to have more hysteresis.

            **Actually it is the integral of the force over the distance traveled. Also, since I’ve been called out for this before, depending on the units you are using, you may need to multiply the force times the distance times a CONSTANT to get a value of energy.

          • mk1313

            So you’re saying that it is impossible to design a piezo-road to be neutral with respect to the rolling resistance compared to current road technology. Can you prove that empirically? I’d wager it is possible as the materials are normally ceramic based which is quite resistant to deformation, though quite possibly too expensive with current tech. You’ve simply reformulated the bellows argument for the piezo effect which is not what I was proposing at all. I am saying keep the deformation and rolling resistance the same but incorporate the piezo crystals and a means of energy harvest without having a negative effect beyond what already exists. If you change those parameters of course the required energy changes, hence why the bellows will not work well except where energy loss from the vehicle is desired. Additionally, piezoelectric transducers are used to transform sound (vibration) into an electric current in microphones. Are you saying such vibrational energy is absent from vehicles running over a road? Again, I am not commenting on economic feasibility but technical.

          • Andrew Snow

            “So you’re saying that it is impossible to design a piezo-road to be
            neutral with respect to the rolling resistance compared to current road

            No, I wasn’t saying that. When you formulate the question very precisely like this, then it could theoretically be done. But, it won’t provide free or even cheep electricity.

            Consider this, smooth steel wheels on a smooth steel road (e.g. trains on track) have substantially less rolling resistance than rubber tires on pavement. Thus, if you used steel wheels (with no tires) and made a steel roadway with piezoelectric cells under it, you could achieve what you suggest. That is, a piezo-road that is
            neutral with respect to the rolling resistance compared to current road technology.

            But, and this is really the issue here, any energy generated by the piezoelectric elements is still coming from the engine in your car. The steel road and wheel combination would have even less drag, and you would get even better fuel economy if the piezoelectric stuff was not under the steel road surface.

            “Additionally, piezoelectric transducers are used to transform sound
            (vibration) into an electric current in microphones. Are you saying
            such vibrational energy is absent from vehicles running over a road”

            Again, no, that is not what I said. Energy can be harvested from all sorts of incidental sources. Right here in my hand I have a Stirling cycle engine that runs only from the heat of my hand.* But, the engine cost me about $100 and the amount of power it puts out is minuscule. It’s not a practical way to generate power.

            The article above is talking about generating significant amounts of power, and doing it on the cheep. You won’t get cheep power if you start with tiny energy sources like the vibrations in a car. Even when you start with a massive energy source that is relatively easy to harness – solar, wind, tidal, geothermal – it is hard to get the cost of producing electricity below that of fossil fuels.

            * To be technically correct, my Stirling engine is running by transferring heat energy from my hand to the air in the room.

          • mk1313

            As I said Piezo materials are often ceramic. Why would their incorporation into the asphalt matrix necessarily increase either pavement flex or energy loss for the vehicle? You seem to want to go to extremes to denigrate the idea. The point was that though the bellows inherently increases energy loss there are technologies that can do the same without altering the current situation. The idea of harvesting wasted energy is valid but the means need to be thought out not to make the situation worse.

  • Zwerius

    And where do you think the energy is coming from….?
    Exactly, to be supplied by the car….

    • cmeyer

      Agreed! Why not just put little wind turbines on our cars to generate electricity? The (failed) logic is basically the same. As for pedestrians doing this work, maybe, but if walking on such surfaces is even slightly more strenuous they’ll simply go around.

    • Omega Centauri

      Physics says, there is no free lunch. We take a low efficiency method of producing mechanical motion (ICE engines, and worse if you include the food system people), and then take some of the mechanical energy and with low efficiency convert it to electricity. This is a bad deal, if you are trying to obtain bulk power. Why not just put the vehicles on a treadmill?

      These sorts of things may be useful in cases where you can avoid extending grid power, perhaps you need a few sensors on a stretch of road that doesn’t have wires going to it. Then stealing power from stuff like mechanical vibrations might better than stringing wires. But, otherwise this is a lose lose from the efficiency standpoint.

Back to Top ↑