2.4 megawatt energy recycling system for New York subway

[Fledermaus]

At the desk sat Robert W. Lobenstein ? Loby to his friends ? with a radio in his hand and a look of excitement on his face that only someone with an engineering degree can have.

"Five . . . four . . . three . . . two . . . one," he called into his radio. "Full acceleration southbound!"

Despite the distant roar, Mr. Lobenstein, the general superintendent of power operations for the subway, was not launching a shuttle. He was launching a train ? one of the brand-new models starting to appear now on the L line ? along a 10,000-foot test track just outside the barn.

http://www.nytimes.com/2002/07/30/nyregion/30TUNN.html

Pentadyne Power Corporation (www.pentadyne.com), a world leader in flywheel
energy storage systems, announced that the Metropolitan Transit Authority of New
York (www.mta.nyc.ny.us) will use Pentadyne as the supplier of a 2.4 megawatt
energy recycling system that will be used to capture, store and reuse braking
energy of trains on a station of the Long Island Railroad.

The MTA oversees all of New York City`s world-renowned subways, commuter trains
and buses. It is North America`s largest transit authority, providing 2.6
billion passenger trips each year - the equivalent of about one in every three
users of mass transit in the United States and two-thirds of the nation's rail
riders.

The pilot project has major financial support from the New York Power Authority
(www.nypa.gov), which selected Pentadyne as the supplier.

The project will involve an array of sustainable, environmentally responsible
carbon-fiber flywheel systems that capture and store braking energy from slowing
trains, then reuse that energy for acceleration.

http://www.reuters.com/article/pressRelease/idUS202963+13-Aug-2009+BW20090813

[HamdenRice]

1. Here's a weird question about this -- what about the gyroscope effect?

I'm assuming these are flywheels within each train. Will the gyroscope effect of these large flywheels make the trains more resistant to turning?

[phantom power]

2. Usually solved with counter-rotating pairs.

[HamdenRice]

3. Thanks nt

[Fledermaus]

4. Subways have their own grid. The flywheels are stationary.

The train uses its motors as generators to slow down. The power is put out on the grid and the flywheels spin up. When the train leaves the station, the flywheels slow down and gives the power back to the train.

[HamdenRice]

5. My Dad worked for the subways for 40 years, so I'm familiar with it's separate grid

but I'm surprised that braking trains could put power back into the grid. They are iirc, DC while the city grid is of course AC.

Thanks for the explanation. Very weird concept.

[JohnWxy]

6. very smart. The best solution is the most elegant.

tried to recommmend but was beyond the time frame.