Soccket Ball

[jerryyu]

http://www.inhabitots.com/energy-generating-soccer-ball-brings-power-to-developing-nations/

 

I am curious about they store the electricity generated by the soccket ball. If they used a capacitor, what kind? Because a regular capacitor won't be able to store enough electricity to light an LED for three hours. A rechargeable battery? How did they do it?

 

Sidenote: according to them, a 10 minutes play(or charge) can generate enough energy to light a LED light flashlight for 3 hours. A capacitor definitely can not do that, at least I don't think so.