Flywheels (what is the biggest automotive / truck / lorry one you know of?)

[Bill in Houston]

This is an interesting quote from this site:
http://www.mpoweruk.com/alternatives.htm
Energy storage in a flywheel is as old as the potters wheel. Slow speed flywheels, combined with opportunity charging at bus stops have been used since the 1950s for public transport applications, however they are very bulky and very heavy and this has limited their adoption.

This combination of quotes seems to me to indicate that you could store about 0.1 kWh. Is that very much or not?
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The energy stored in a flywheel is given by the following formula
E = ½ Iω2
<snip> and ω is its rotational velocity (rpm).
<snip>The magnitude of the engineering challenge should not be underestimated. A 1 foot diameter flywheel, one foot in length, weighing 23 pounds spinning at 100,000 rpm will store 3 kWh of energy.
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So if your flywheel weighs twice as much, and spins at 10,000 rpm (so I can do the math in my head) then you would store 0.06 kWh. 0.01 kWh is 341 BTU, which is 0.4 oz of gasoline. Or maybe I'm doing the math wrong.

A horizontal spare tire well would be a great place to put the flywheel, it seems. With a horizontal flywheel you avoid weird procession (is that the right word) effects when you go around corners.

[cfg83]

landspeed -

Originally Posted by landspeed

...

I do want to create this project, as part of my long-term 'hybrid' conversion plans for my car. I guess I will also have fun doing (underground) destruction testing of a few flywheels too! (Get an oil drum, bury it deep in the ground, , have the flywheel inside this, and drive the flywheel via a long shaft attached to a 10kw motor, and monitor the resonance, rate of energy loss, and so on!. Then speed it up, measuring the RPM, until it fails!. Then see how much damage it did to the containment system!

My Energy Conservation Architecture professor from the 1980's told me a funny story about a flywheel car he rode in the 1960's. They were driving along fine and dandy, when all of a sudden BAM!!!!, the flywheel explodes straight up out of the hood and into the sky. Nobody got hurt, but it was definitely sobering.

CarloSW2

[landspeed]

That's why I'm looking at e.g 7000rpm flywheels, rather than 100,000rpm The idea really would be a temporary, small-capacity energy-storage system, but with more energy storage capability than (currently availabe) ultracapacitors.

I wouldn't like to see what happens when a flywheel, with enough energy to drive a car for 300miles, fails . The flywheel car diagram posted above was interesting - you can see that the fly wheel will fail in a sideways direction, or up + down, but would avoid the passenger cabin. I assume this was by design!

[Bill in Houston]

Yeah, if something can just hold enough energy for all the times I go from 30 mph to 0 and than back up to 30 mph, that would be awesome. I don't need 300 miles...

[landspeed]

And.... it could also be used as a temporary regen braking energy store, so, you can do 'full' regen into the flywheel, which then (more slowly) recharges the batteries.

[landspeed]

I'm not saying I've been put off by flywheel energy storage, but.....

http://www.sxoc.co.uk/vbb/showthread.php?t=295606

This has photos of a Nissan Skyline that had a flywheel explosion at max rpm - but it was a stock flywheel in a stock car. And it opened the gearbox like a tin can, as well as cutting through the chassis and the bonnet :O

[Lug_Nut]

http://www.time.com/time/magazine/ar...romoid=googlep