So you have two magnetic plates that levitate an iron/metal ball perfectly in a cylinder that has a vacuum inside. Kinda like this --- O <---<< floating with magnets in a vacuum. --- You spin the ball - giving it kinetic energy. Keep in mind you can give it as much energy as you want (all the energy in the universe) since it'll never spin faster than the speed of light. Now, to extract energy, all you have to do is add a gas into the vacuum - the gas and the iron ball get hot due to friction. You set up a kind of heat pump that draws away heat from the battery into a cooler place, there creating a gradient = energy. I've been playing around with the math and check this out: Let's say you wanted to store about 10,000,000 J - basically enough to power a standard us home for 1 day in a 1 kg ball of metal with a radius of 1 m. sqrt(10000000/(.5*.4)). That gives the bitch an angular velocity of about 7000 rad/s. LOL! Pros: Can store potentially HUGE amounts of energy in a small space. WAY more than a regular battery Can almost instantly "charge" it - getting it going at 7krad/s shouldn't take more than a few seconds at a charge station. Cons: Having a big ball spinning that fast has to be some kind of hazard. The magnetic fields would have to be on point to contain it. Not as "efficient" as a chemical battery. Oh peweeeppp u iz so, so smart. Thank you bby i knw.