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Powering the surrounding neighborhood using friction from passing cars

  1. Sep 12, 2016 #1
    Hi guys,

    I am curious to find if there is any invention where the friction between the surface of motorway and cars' tyres are used to create kinetic energy which can be converted into electrical energy to power up the houses and plants around them.

    Thank you.
     
  2. jcsd
  3. Sep 12, 2016 #2
    I remember seeing a project, not from heat generated, but from mechanical stress applied to the material:
    Piezoelectricity

    also check out "Sustainable Dance floor"
     
  4. Sep 13, 2016 #3

    mfb

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    Using the inefficient car motors together with an inefficient friction to electricity conversion sounds ... inefficient. The cars would need more fuel, burning that additional fuel in a conventional power plant produces much more electricity.
    Those applications can be useful if the energy would be wasted anyway (vibrations, stray electromagnetic radiation, ...) or if regular powering is impractical (very remote locations, too many sensors at different places, ...), or if it is part of some art installation. Putting such a thing in a street does not make sense.
     
  5. Sep 13, 2016 #4

    CalcNerd

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    mfb, are you speculating or do you have a reference? Below is a reference that refutes your speculation. The Israelis' put just such a device in operation. This was mentioned by me in an earlier post.

    https://www.iroads.co.il/sites/default/files/mtsgt_1_innowattech_presentation_-lucy_edery-azulay.pdf

    Before you defend yourself, I suspect all of your assertions are true and my reference is very likely hyperbole by an interested party that wants to sell, sell, sell. I cannot envision any reasonable ROI, unless the is no other power source available.
     
  6. Sep 13, 2016 #5

    mfb

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    For the first part: with worse fuel than car petrol, power plants achieve efficiencies of more than 30% (e. g. 10814 BTU/kWh, conversion). Cars are below 30%, see e.g. this diagram.
    For the second part: I won't give a reference for conservation of energy.

    The test project you linked to seems to be mainly about monitoring the traffic. That is one of the applications I mentioned: many distributed sensors, the system is much easier to install if it produces its own power.

    They claim to get 200 kW per km of road at 600 "heavy" vehicles/hour going 72 km/h. Car tires have a typical rolling resistance of 0.01, as Wikipedia cites "Gillespie ISBN 1-56091-199-9 p117". If heavy vehicles have a mass of 10 tons, total power of rolling resistance is 10000 kg * 9.81 m/s^2 * 0.01 * 1km * 600/hour = 160 kW.
    Something is wrong here...
     
  7. Sep 18, 2016 #6

    JBA

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    For piezoelectric generators the friction or rolling resistance of the tires are totally irrelevant, only the applied vertical loading due to the weight of the vehicle is required to produce a power output; and the use of pads or strip using this technology has zero effect upon the efficiency of the vehicle passing over the generating pad or strip.
     
  8. Sep 18, 2016 #7

    mfb

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    It has an effect, you cannot violate energy conservation. If the pad decreases its height under pressure (useful to extract energy), it means the car goes down, and has to use more power to go up again - the car is effectively driving a tiny bit uphill then.
     
  9. Sep 18, 2016 #8

    JBA

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    Yes, by a few thousands of an inch; which is from a practical point of view is negligible; and, probably would be an improvement over the similar effects from the surface variations of standard road construction.
     
  10. Sep 18, 2016 #9

    OmCheeto

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    Sounds like an outrageously expensive proposition to me. I'd rather see energy harvested be put back into the vehicle.

    Simply replace standard shock absorbers(mechanical to thermal energy dissipaters) with something that doesn't throw the energy away.

    Google scholar list for: energy harvesting shock absorber
     
  11. Sep 18, 2016 #10

    mfb

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    It is small compared to the power of the car, but the energy harvested in the road is even smaller. Do you want to neglect that as well?
     
  12. Sep 18, 2016 #11

    JBA

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    I was referring specifically relative to the energy harvested by the surface and elevation irregularities and road paving seams that exist in US standard roads and streets, not the power level of the automobile.
    At the same time, given the current movement to EV's of all forms, I think OmCheeto's response is the one that makes most sense because it utilizes those road condition irregularities that are already in place.
     
  13. Sep 18, 2016 #12

    mfb

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    It does not matter what you use as comparison. The energy harvested by the road is smaller than the additional energy the cars need. Unless you also introduce some way to make cars have lower losses - but then you could simply implement this feature (like harvesting energy in the shock absorbers, as mentioned) and skip the street power generation.
     
  14. Sep 18, 2016 #13

    JBA

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    Actually, we have already reduced rolling friction losses with the with the new low rolling resistance tires utilized on current EV's.

    As to the feasibility for providing a piezoelectric road to a power grid, it is not necessary for a system to provide 100% of the power required and the percentage available to a structure or neighborhood, that would obviously depend upon the traffic density vs the demand cycle and power storage system capacity On the other hand, the possibility of using it for supplementing power for such items street lighting in heavily trafficked urban areas might be a reasonable scenario now that we have high intensity very low wattage LED's available; but, obviously, the economics of doing so is certainly an issue. There is actually a bicycle path with a trial piezoelectric surface section in one park now operating here in the US that is doing just that (I apologize for not now remembering the exact location and not being to locate and provide the appropriate reference).

    There was a time when no one believed that solar panels could be viable for powering vehicles; but, currently there is a complete neighborhood in Austin Texas that is operating their EV's and supplying daytime power for the homes without power from the local power grid by using their home roof solar panels and power storage units. Also, in Germany, where they are heavily invested in solar power, they recorded one day recently when solar provided 25% of the country's total power requirements. (Something that, to be candid, surprised me due to Germany' very high 50° N latitude and the Sun's 23.5° N Summer Maximum Solstice angle.
     
  15. Sep 18, 2016 #14

    DaveC426913

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    Sorry, negligible input = negligible output.

    Non-negligible output will require non-negligible extraction from the vehicle. It is extracting energy at the car's expense.

    The way to use roads to create powere is to harvest energy that is otherwise unavoidably wasted. Heat, is just one example.
     
  16. Sep 18, 2016 #15

    mfb

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    @JBA: Sorry, but you are missing the point. All those things do not magically get power from nowhere - the cars have to work harder to operate them. Those devices would just work like power plants burning petrol at low efficiency. Would you let your car run at home to produce electricity with a generator attached? No - it would be way too expensive to use the high-quality petrol for that.
     
  17. Sep 18, 2016 #16

    russ_watters

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    mfb already dealt with the conservation of energy issue, but:
    That's an assumption and while I doubt it is correct, even if we assume it is correct, it just means we should make smoother roads and get an even bigger benefit than making a road smoother, then rougher again, to harvest energy.

    Now, that isn't to say there couldn't be an application for this. A self-powered car-counting road sensor, for example. Let's just not pretend it would be "green".
     
  18. Sep 19, 2016 #17

    JBA

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    My position is that the energy loss everyone is concerned about already exists and is currently being lost as heat transferred to the road etc; and, as for the process's greenness, the greenness of the created energy will be dependent upon the greenness of the vehicles producing it. be they automobiles or mass transit not the conversion technology itself.
    I am not disputing the scientific fact that the process is technically a "transfer of energy". I am simply pointing out that all of the real world elements related to its application have to be addressed in judging its potential viability. The majority of our advancing technology is generally based upon better solutions not what might be the best one, because most of the time what might be the best solution is a moving target often not even yet envisioned, realized or capable of being implemented with the technology available at that point in time.
     
  19. Sep 19, 2016 #18

    DaveC426913

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    OP seems to have been pushed off the face of the Earth. Any point in pursuing this, except academically?
     
  20. Sep 19, 2016 #19

    mfb

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    The systems don't get that energy. The installation of the proposed systems does not reduce the losses, it increases them.
    In other words: very poor.
     
  21. Sep 19, 2016 #20
    I think the technology may not be a necessity now, but I imagine if there were remote areas that could not generate electricity through wind, solar, or fossil energy, this could be used in any environment that there is a source of traffic (people, cars, trains). To counter the loss of the car efficiency, there would need to be a desperation for sources of electricity.

    Such as underground locations.
     
    Last edited: Sep 19, 2016
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