[quote=@Ophidian]
<Snipped quote by TheSovereignGrave>

You know that whole energy can't be created or destroyed rule?

Forget that rule. 
[/quote]

Thats not generally how Vacuum energy works though, you arent creating energy you are harvesting it from the vacuum, Vacuum energy would probably be best for low yeild power generation though, better for powering probes and not giant battleships