Maybe this should be in Navy threads but it does have some general interest.
THE ZUMWALT AND THE RAIL GUN: THE ENERGY HUNGRY NAVYSpeaking of railguns, another energy-intensive weapon system that could come into play is the Navy’s new laser weapons system (LaWS). Unfortunately, the power requirements for the Navy’s Rail Gun appear that the Navy will not be able to do any run and gun maneuvers. It is estimated that the ship would have to be at full stop to rapid fire a rail gun. Of course that could change with a different power plant.
As the technology advances, and faced with rising and unpredictable fossil fuel costs, the Navy’s next-generation of surface littoral class combatant ship will leverage electric ship technologies in conjunction with new smaller nuclear power plants with the design characteristics of better speed, weight, maneuverability, range, and cost—and capable to power multiple directed energy weapons at full speed.
http://energyfromthorium.com/2014/04/04/zumwalt-rail-gun-energy-hungry-navy/