3 ms·

Would save even more energy if they were attached to a generator...

• jacquesm 17y ago
  You're probably just joking, but in case you aren't, no it would just cause all the users of the door to have to consume that much more in calories.
  • fhars 17y ago
    If there are enough children entering your building, it might just work. On a more serious note, people do actually use this to improve the supply with drinking water in developing countries by attaching a water pump to a roundabout, search for "playpump".
  • pbhjpbhj 17y ago
    The door must be hinged, it also has a braking system to prevent it from rotating too quickly. Adding resistance to drive a generator in place of heat/sound generation seems not unreasonable. In cars I think they call it regenerative braking. Of course an analysis of the heat loss path will help to determine if this is worthwhile or if the heat can be used more directly to aid heating the building.
    • jacquesm 17y ago
      A regenerative system on a door that has brushes that cause friction with the sides isn't going to make more power than it will cost to create a regenerative braking system in the first place. It adds a whole layer of complexity that will affect reliability and in the end it's going to 'save' piddly little bits of power. If you take the cost of an energy storage system you have to divide the price of the unit by the amount of power that you can buy for that money discounted with what you think power will cost over the lifetime of the unit. This will most likely come out negative.