The Leyden jar capacitor posted the other day fails to compare to what [FastMHz], one of the members over at the 4HV.org forums, has been busy building, a 24kj capacitor discharge bank. This capacitor bank will be configured for 4500v @ 2400uF and can be charged up slowly using microwave oven transformers. It can then release all its stored energy in under a millisecond through a triggered spark gap. This allows for some pretty big sparks as seen in this video, we are not sure about the laughing in the video maybe the power has gone to his head?
A bank like this can be used for a railgun, induction launcher, or exploding things in general. Coin shrinking and can crushing require much quicker discharge rates than what electrolytic capacitors are really capable of, and generally perform better with large pulse capacitors, however it will be interesting to see the final use for this potential energy.