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Green Elevators

  1. Apr 18, 2015 #1


    Staff: Mentor

    There has been much talk about regerative braking on PF lately. With that in mind, this article in today's Washington Post caught my eye. It talks about Otis Elevator's newest design which the article claims is 75% more efficient than conventional elevators.


    How did they do it? The (non technical) article says via improvements in lighting (I guess LEDs), less friction in the cables due to cable design, and regenerative braking. I would love to learn what fraction of the savings came from reduced friction, but the article doesn't say.

    Note that this reganerative braking scheme has all the advantages. The motors, and the drive electronics are needed anyhow, and the load to be served by regenerative power is within the building. The energy does not need to be stored, nor negotiated for sale to a third party.

    Most interesting is a bar graph showing where the energy was spent in the newest elevators compared to conventional ones. The savings in lighting and drive power are obviouis. But control systems dissipation actually increased, and now appears to account for 2/3 of the energy consumption. I smirk at the irony, becuase that opens the door to future critics who might attack the wasteful smart control systems as energy hogs. You and I know that this is a good thing, but politics does not follow logic.

    What about Moore's law? Be careful. The smart microchips will not be dissipating all that energy, it must be the high power electronics. I don't think Moore's law applies to power electronics. However, improving the efficiency of power elecctronics might be a fruitful field of reasearch in coming decades.
  2. jcsd
  3. Apr 18, 2015 #2


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    2017 Award

    Staff: Mentor

    I agree. I would expect that every CPU that is still in production has enough computing power for escalators and elevators, and the simple ones do not need 100 W (-> 1000 kWh/year control systems). There has to be something else in the control system that needs more power.

    Should we use the elevator or escalator to go down now to save energy?
  4. Apr 18, 2015 #3


    Staff: Mentor

    Years ago, I worked at ASEA in Sweden. We made SCRs the size of large pizzas. Those babies could dissipate quite a few watts.

    Outstanding, walk up - ride down. Improve your health while you're saving the world. Will that become the new social meme?
  5. Apr 18, 2015 #4


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    Gold Member

    The regenerative is only for braking - braking to slow to a stop at a floor either going up, or going down.
    Still, using the stairs is a good workout.

    The counterweight is chosen for balance, so the motor uses as much ( wasteful ) energy to accelerate the car up or down.
    People load in the car does have an affect but that is variable.
    In which case, the elevator should only be used when it is full for maximum savings.
    With only one person inside - now that is just like driving on the road as the single lone occupant..
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