Quote Originally Posted by Mr. Carnelian View Post
Possibly nuclear fission reactors. Cold fusion - i.e nuclear fusion which uses less, ideally significantly less, power to initiate than it produces - could be just around the corner, relatively speaking, although it's seemed like it could be "just around the corner" on and off for decades, so who knows.
[/spoiler]
Cold fusion is a joke. The First and Second Laws of Thermodynamics prohibit it.