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An elevator is like a massive piston, going up and down, hundreds of times a day in a narrow space, air rushing past at high speed.
Putting a stiff skirt around the elevator car and a wind turbine at the top and bottom of each lift shaft in a high rise building should recapture a sizable chunk of
the energy used to shift the elevator up and down each time.
[link]
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Ah yes, the free energy Marilyn Monroe lift. |
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//should recapture a sizable chunk of the energy used //
Though you might have to recalibrate the braking profiles at the top and bottom. [+] |
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I'm guessing that currently lift shafts are not sealed but that there is some clever way in which the shaft is ventilated to avoid air pressure building up ahead of an advancing lift. If this is the case, then sealing the lift shaft and installing turbines will require more energy to push against this - unless you only do this when the lift is falling, and so making the turbine go round is part of the braking process. However, there may be more efficient methods of energy recovery than this. |
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One of the issues with lift design is making sure that air can get past them easily as they move up and down.. That means making them smaller in cross-section than the shaft. |
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The trick will be to seal off the space around the car, to create a sufficient draught to power the turbine. |
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I must admit I can't see much point in doing the maths to figure out whether it's more or less efficient than current paractice. This is definitely a poorly thought-out idea. |
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Wouldn't the most efficient method be a vacuum in the shaft?
That way there would be no resistance, and the wasted energy
need not be expended in the first place. |
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//the wasted energy need not be expended in the first place//
Apart from the extra weight of the fully-sealed and reinforced cars. |
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Unless all passengers were able to hold their breath, from start to stop on each trip. |
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That would make more sense - then you'd put businesses like "Acme Free-Diving Training School" on the 50th floor. |
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Alongside a first aid station, to treat burst eardrums and pneumothoraxes, with the pressure change that 50 storeys entails. |
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Save energy by reducing air resistance - rather than having the air move around the lift, make it a skeletal structure of carbon fibre and titanium, that the air can rush through with least resistance. |
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"Mood lighting" up and down the lift shaft, maybe with a little bit of artificial fog for that lovely Ridley Scott look .... |
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The photocopier guy returns in "Stationery Runner - This time its personalised" |
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Most elevators use a counter-weight, so the actual energy expended is a lot less than you think. The motor that moves the elevator up and down is not very big. |
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Yeah, there's no real energy to be had. But consider a different scenario - |
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All the lifts are pistons with no cables or counterweights). The top and bottom of each is connected to some glorified valve switching gear. When a lift comes down it generates a pressure below it. This could be routed into a lift going up. Just add a few pumps and a computer controlled load balancer. |
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You'd be better using the mechanical energy from descending lifts to pump water up into a header tank. Energy recovery on pumped storage systems can be pretty good, and you could have lots of lovely pipes (or even a waterslide) on the outside of the building, like Lloyds, or the Pompidou centre. |
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Why not seal the lift to the shaft like a piston, and drive it up and down by changing the pressure of gas above and below it? |
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Although when people step out, it'd probably shoot upwards, and then the high pressure gas below it would explode out the entrance, possibly killing the people who just left. |
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Using energy to drive a motor to drive a lift and then use the air the lift is moving to generate energy, not so good. |
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You would be better off using regenerative braking on the motor. Even then, with counterweights, you wont get much out. |
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Brunel was thinking like this with the atmospheric railway - he used leather seals around a piston with a vacuum ahead of the train. The lift scheme is like the wind-tubine heavy weight winding idea (Wind Turbine Gravity Storage) in that the amount of energy recovered is too small to bother with. |
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If the energy is already being expended then there's no harm in recovering some of it. It's not spending energy to garner some. It's recovering energy that would otherwise be pissed away in heat and noise. |
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But if there is a counterweight, the best plan is no resistance
at top or bottom. Any kind of turbine would cause
resistance, that's what they do. |
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If not, then just open a valve at the top and let it rip. It
would make a cool installment in the lobby if the turbine
were in a clear enclosure. |
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//Any kind of turbine would cause resistance// Agreed. If you had a lift shaft with a turbine installed you could make more energy available by preventing the blades from turning, and even more by removing the turbine completely and leaving a big hole. |
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Using the moving air more directly, such as to help ventilate an underground carpark, might have more merit. |
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