3 ms·

You mean a flywheel: http://en.wikipedia.org/wiki/Flywheel_energy_storage http://en.wikipedia.org/wiki/Flywheel_energy_storage They're in use for a number of

by wffurr 13y ago

You mean a flywheel: http://en.wikipedia.org/wiki/Flywheel_energy_storage http://en.wikipedia.org/wiki/Flywheel_energy_storage They're in use for a number of applications, namely in datacenter UPS systems. The main downside is a catastrophic failure mode. Lots of mass, spinning at high speed. Just apply imagination. Their energy density is pretty good relative to batteries, which is to say terribad compared to hydrocarbons. Good ones are pretty expensive, and they require periodic servicing for bearings, gaskets (for vacuum sealed systems), etc. Generally limited to niche applications for now, but there are various pilot projects to look at them for train system energy recovery and grid storage.

pygy_ 13y ago
For safety, they can be burried, can't they?
tehwalrus 13y ago
yeah, my thought process had some pretty complicated failure systems. The thing is, with magnetic suspension, you can "catch" the thing using it's own energy. With a good and fast enough controller, you could catch the thing where it is and flood the tube with air to slow it down. since all you're doing is dissipating energy, you can use it to soften the crash. In terms of energy density, you can just *keep increasing the speed can't you?
- pbhjpbhj 13y ago
  >In terms of energy density, you can just increasing the speed can't you? // In which case you only need a tiny mass to start with ... The speed limitation is presumably going to come in with the rate at which you can alter the magnetic field to still accelerate the mass. Also you'll get drag as it impinges on local fields (Earth's magnetic field) and there'll presumably be eddy currents and local electrical fields to cope with too which will become more significant at higher flux rates.
  - tehwalrus 13y ago
    :( you're probably right, the universe always finds a way to ruin all the good ideas.
- Detrus 13y ago
  You can't increase RPM very far. The flywheel will tear apart. If you research the topic you'll find they have to use fancy composites to get to 100,000 RPM. A metal wheel would blow up by 50,000. Train and car regenerative breaking uses flywheels. In trains they don't spin fast, but they're heavy. That's another way of increasing storage density, use a heavier wheel at a moderate speed. Neutron star matter would be perfect.
  - tehwalrus 13y ago
    of course, I had forgotten about centrifugal force. what a moron, sorry! I'm not sure I'd want a quasar in my back yard, but thanks :)

by wffurr 13y ago

pygy_ 13y ago

For safety, they can be burried, can't they?

tehwalrus 13y ago

yeah, my thought process had some pretty complicated failure systems. The thing is, with magnetic suspension, you can "catch" the thing using it's own energy. With a good and fast enough controller, you could catch the thing where it is and flood the tube with air to slow it down. since all you're doing is dissipating energy, you can use it to soften the crash. In terms of energy density, you can just *keep increasing the speed can't you?

pbhjpbhj 13y ago
>In terms of energy density, you can just increasing the speed can't you? // In which case you only need a tiny mass to start with ... The speed limitation is presumably going to come in with the rate at which you can alter the magnetic field to still accelerate the mass. Also you'll get drag as it impinges on local fields (Earth's magnetic field) and there'll presumably be eddy currents and local electrical fields to cope with too which will become more significant at higher flux rates.
- tehwalrus 13y ago
  :( you're probably right, the universe always finds a way to ruin all the good ideas.
Detrus 13y ago
You can't increase RPM very far. The flywheel will tear apart. If you research the topic you'll find they have to use fancy composites to get to 100,000 RPM. A metal wheel would blow up by 50,000. Train and car regenerative breaking uses flywheels. In trains they don't spin fast, but they're heavy. That's another way of increasing storage density, use a heavier wheel at a moderate speed. Neutron star matter would be perfect.
- tehwalrus 13y ago
  of course, I had forgotten about centrifugal force. what a moron, sorry! I'm not sure I'd want a quasar in my back yard, but thanks :)