The Navy has test fired their new electric rail gun. Fires a shot at Mach 7.5 and is traveling at Mach 5(cue Speed Racer music), when it accurately hit's it's target 200 miles away. It generates 10.6 megajoules of muzzle velocity. 306 megajoules=1 kilowatt hour. Seems to me, then, it generates around 3 kilowatt hours of energy when it shoots. Explosive!
To put in perspective, in some future dystopia the Duchy of Dallas can fire a round at the Saxony of Shreveport and pretty much hit whatever they want, in less than 3 minutes from firing.
The Register has a story on it.