Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Flywheel Energy Storage

  1. Aug 28, 2010 #1
    I have an idea pertaining to energy storage in flywheels, something like they do in the KERS, and need assistance here...

    Ok, my idea involves using a flywheel of around 10 kg (steel) with I~1 kg.m^2, to be charged to an RPM of around 7,000 RPM.
    This allows E = 0.5 x 1 x (7000x2x pi /60)^2 = 268 KJ of energy to be stored.

    I want to charge it with a small engine (something like a Honda GX50) which, according to the charts will give max torque of 3 Nm at 4000 rpm and max power of 1.6 kW at 7000 rpm (approx).

    I want to discharge it to run a light vehicle (170 kg including driver) such that the discharge takes place at one wheel only (a three wheeler). I want discharge in pulses.

    Now, the questions:
    1. How do I calculate the time it takes to charge the flywheel to 7000 RPM? Can I do it without using some intermediate device like a CVT or motor/generator?
    2. How do I calculate the discharge time (and characteristics)?

    Thanks in advance.
     
  2. jcsd
  3. Aug 29, 2010 #2
    I think flywheel energy storage is a really interesting topic, I would love to see more practical uses of them! If you end up making something, please post it.
     
  4. Sep 2, 2010 #3

    Hi-
    1. The time it takes for increase the kinetic energy of the flywheel mainly (but not finally) depends on the characteristics of the energy supplier (your GSX50) and utilizer (in a direct coupling). Write down the energy balance and you will get the dynamics (and then the time). But direct coupling seems to me a not real event..
    2. For the discharge time you can use the same approach, this time the flywheel is the motor.

    M
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook