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Fuel Saving Flywheel for Trains

store/retrieve energy when stopping and starting a train
  (+1, -2)
(+1, -2)
  [vote for,

(note: variations on this idea already exist elsewhere on halfbaked and the internet in general, i know)

Trains expend/waste a great deal of energy when stopping for stations and pulling away again. If only we could store up (some of!) the energy the train sheds under decceleration, in order to reinvest it in the train's subsequent acceleration...

We can! I think. Instead of using traditional brakes (which convert virtually ALL of the train's kinetic energy into heat!), we could install a massive (heavy, not just big) flywheel in or near to the engine. By linking this to the wheels via an inverted gearbox and clutch arrangement, the train could be brought to a halt by driving the massive flywheel upto speed. This process is then reversed to set the train in motion again. Discuss (no pun intended).

(NASA got there first, D'Oh.)

philistyne, Nov 30 2003

Regenerative braking http://www.ctts.nre...visor_doc/regen.htm
[converted, Oct 04 2004]

a VERY brief history of the GE transportation division https://www.getrans...ry.asp?SMSESSION=NO
with links to all kinds of interesting little tidbits that make this idea seem like a child's attempt at perpetual motion. [ato_de, Oct 04 2004]

Parry People Mover http://www.parrypeoplemovers.com/
Purveyors of ultra light flywheel driven rail cars [rambling_sid, Dec 09 2004]


       No flywheels required. Put each station on a little artificial hill, built so that the slope & elevation bring the train nearly to a stop, from normal running speed. The train then brakes to a stop just over the summit and uses the slope back down to ground level to get it going again, simply by releasing the brakes.
Harry Mudd, Nov 30 2003

       Diesel electric trains do this to some extent, the engine braking current is used to cool the engine with fans in the roof of the engine.
PiledHigherandDeeper, Dec 01 2003

       This is being developed for the truck and hybrid market at the moment, but is not in production - i'm sure i will be corrected. should only be simple modifications to apply to the train applications.
converted, Dec 01 2003

       This is already baked in some stations of the New York City subway system. The flywheels are in the station, however, not on the train. The power flows back and forth electrically, through the third rail.
krelnik, Dec 01 2003

       Surely a flywheel on this scale would generate some huge gyroscopic forces?
gooseganda, Dec 01 2003

       Virtually all locomotives (in the US at least) are diesel-electric, so you already have the capacity to do regenerative braking. The trick is finding some way to use the power that you generate. It doesn't necessarily need to be stored. How 'bout refining aluminum, or generating hydrogen on the go? Need to find some process that requires a lot of electricity, but isn't particularly heavy or bulky, so those two might not be the best examples.
toiyabe, Dec 01 2003

       The problem with the hill is that it would cost more to build the hill then you would gain from fuel savings. Plus, you would also need to expend energy to get the loads up to the station for loading, so you really aren't saving that much in energy either (only the potential of the loco and rolling stock).
toiyabe, Dec 01 2003

       Diesel-Electric locomotives already use regenerative breaking to produce electricity for auxiliary equipment, cooling fans, Cab A/C, ditch lights etc. Furthermore, the diesels run at a constant speed for optimum efficiency. The weight of a flywheel massive enough to store that amount of energy would preclude its use.   

       Ya know, General electric has been manufacturing Locomotives for 90 years, and railroads have been operating in this country since Edison built the first experimental one in the 1880s.   

       The problem that you fail to realize, and the fact that you seem to be overlooking is that efficiency is money in transportation. If there was a more efficient (read cheaper) way to operate their locomotives, the BNSF would be falling all over itself to implement it. This is a poorly thought out proposal, have a fishbone.
ato_de, Dec 01 2003

       I assumed he meant electrified railroads. I doubt anybody would actually believe railroads were invented by Edison in 1880.
toiyabe, Dec 01 2003

       Yes I was speaking of electric and diesel-electric locomotives.
ato_de, Dec 02 2003

       Yep! Harry Mudd is right, well almost. One of the earliest lines on the London underground is 'profiled' in this way. The tunnels leave the station is a steep downwards slope with a slow incline to the next station. The original trains had only one power setting, flat out (and stop of course).   

       It is an oldish idea which I read about in a 1903 engineering book.
KiwiJohn, Dec 02 2003

       Very good application for a proven piece of technology.
madness, Jul 31 2004


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